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IR3093
DATA SHEET
3 PHASE OPTERON, ATHLON, OR VR10.X CONTROL IC
DESCRIPTION
The IR3093 Control IC provides a full featured, cost effective, single chip solution to implement robust power conversion solutions for three different microprocessor families; 1) AMD's Opteron, 2) AMD's Athlon or 3) Intel's VR-10.X family of processors. The user can select the appropriate VID range with a single pin. Control and 3 phase Gate Drive functions are integrated into a single cost effective IC. . In addition to CPU power, the IR3093 offers a compact, efficient solution for high current POL converters.
FEATURES
x x x x x x x x x x x x x x x x 5 bit or 6 bit VID with 0.5% overall system accuracy Selectable VID Code for AMD Opteron or Athlon or Intel VR10.X Programmable Slew Rate response to "On-the-Fly" VID Code Changes 3A GATELX Pull Down Drive Capability Programmable 100KHz to 540KHz oscillator Programmable Voltage Positioning (can be disabled) Programmable Softstart Programmable Hiccup Over-Current Protection with Delay to prevent false triggering Simplified Powergood provides indication of proper operation and avoids false triggering Operates up to 21V input with 7.9V Under-Voltage Lockout 5V UVL with 4.36V Under-Voltage Lockout threshold Adjustable Voltage, 150mA Bias Regulator provides MOSFET Drive Voltage Enable Input OVP Flag Output detects high side fet short at powerup Pin compatible with IR3092, 2-phase PWM Control IC Available 48L MLPQ package
ORDERING INFORMATION
Device IR3093MTR * Samples Only *IR3093M Order Quantity 3000 per Reel 100 piece strips
PACKAGE INFORMATION
VID2 VID1 VID0 VID5 5VREF OVPSNS ENABLE OVP CSINP1 CSINM1 NC VCCH1
Page 1 of 39
LGND SETBIAS VCC CSINP3 CSINM3 BIASOUT PWRGD CSINP2 CSINM2 VID_SEL VCCL3 GATEL3
VID3 VID4 ROSC VOSNSOCSET VDAC VDRP FB EAOUT SS/DEL SCOMP2 SCOMP3
IR3093
48LD MLPQ
GATEH1 PGND1 GATEL1 VCCL1_2 5VUVL GATEL2 PGND2 GATEH2 VCCH2 VCCH3 GATEH3 PGND3
48L MLPQ (7 x 7 mm Body) - JA = 27oC/W
07/15/04
IR3093
PIN DESCRIPTION
PIN#
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48
PIN SYMBOL
VID3 VID4 ROSC VOSNSOCSET VDAC VDRP FB EAOUT SS/DEL SCOMP2 SCOMP3 LGND SETBIAS VCC CSINP3 CSINM3 BIASOUT PWRGD CSINP2 CSINM2 VID_SEL VCCL3 GATEL3 PGND3 GATEH3 VCCH3 VCCH2 GATEH2 PGND2 GATEL2 5VUVL VCCL1_2 GATEL1 PGND1 GATEH1 VCCH1 NC CSINM1 CSINP1 OVP ENABLE OVPSNS 5VREF VID5 VID0 VID1 VID2
PIN DESCRIPTION
Inputs to VID D to A Converter Inputs to VID D to A Converter Connect a resistor to VOSNS- to program oscillator frequency and FB, OCSET, BBFB, and VDAC bias currents Remote Sense Input. Connect to ground at the Load. Programs the hiccup over-current threshold through an external resistor tied to VDAC and an internal current source. Regulated voltage programmed by the VID inputs. Current Sensing and Over Current Protection are referenced to this pin. Connect an external RC network to VOSNS- to program Dynamic VID slew rate. Buffered IIN signal. Connect an external RC network to FB to program converter output impedance Inverting input to the Error Amplifier. Converter output voltage is offset from the VDAC voltage through an external resistor connected to the converter output voltage at the load and an internal current source. Bias current is a function of ROSC. Also OVP sense Output of the Error Amplifier Controls Converter Softstart, Power Good, and Over-Current Timing. Connect an external capacitor to LGND to program the timing. Compensation for the Current Share control loop. Connect a capacitor to ground to set the control loop's bandwidth. Phase 2 is forced to match phase 1's current. Compensation for the Current Share control loop. Connect a capacitor to ground to set the control loop's bandwidth. Phase 3 is forced to match phase 1's current. Local Ground and IC substrate connection External resistor to ground sets voltage at BIASOUT pin. Bias current is a function of ROSC. Power for internal circuitry and source for BIASOUT regulator Non-inverting input to the Phase 3 Current Sense Amplifier. Inverting input to the Phase 3 Current Sense Amplifier. 200mA open-looped regulated voltage set by SETBIAS for GATE drive bias. Open Collector output that drives low during Softstart or any fault condition. Connect external pull-up. Non-inverting input to the Phase 2 Current Sense Amplifier. Inverting input to the Phase 2 Current Sense Amplifier. Ground Selects VR10.X VID, Float Selects OPTERON VID, VCC Selects ATHLON VID Power for Phase 3 Low-Side Gate Driver. Phase 3 Low-Side Gate Driver Output and input to GATEH3 non-overlap comparator. Return for Phase 3 Gate Drivers Phase 3 High-Side Gate Driver Output and input to GATEL3 non-overlap comparator. Power for Phase 3 High-Side Gate Driver Power for Phase 2 High-Side Gate Driver Phase 2 High-Side Gate Driver Output and input to GATEL2 non-overlap comparator. Return for Phase 2 Gate Drivers Phase 2 Low-Side Gate Driver Output and input to GATEH2 non-overlap comparator. Can be used to monitor the driver supply voltage or 5V supply voltage when converting from 5V. An under voltage condition initiates Soft Start. Power for Phase 1 and 2 Low-Side Gate Drivers. Phase 1 Low-Side Gate Driver Output and input to GATEH1 non-overlap comparator. Return for Phase 1 Gate Drivers Phase 1 High-Side Gate Driver Output and input to GATEL1 non-overlap comparator. Power for Phase 1 High-Side Gate Driver Not connected Inverting input to the Phase 1Current Sense Amplifier. Non-inverting input to the Current Sense Amplifier. Output that drives high during an Over-Voltage condition. Enable Input. A logic low applied to this pin puts the IC into Fault mode. Dedicated output voltage sense pin for Over Voltage Protection. Compensation for internal voltage reference rail. Inputs to VID D to A Converter Inputs to VID D to A Converter Inputs to VID D to A Converter Inputs to VID D to A Converter
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07/15/04
IR3093
ABSOLUTE MAXIMUM RATINGS
Operating Junction Temperature.................150 C o o Storage Temperature Range......................-65 C to 150 C
PIN 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 NAME VID3 VID4 ROSC VOSNSOCSET VDAC VDRP FB EAOUT SS/DEL SCOMP2 SCOMP3 LGND SETBIAS VCC CSINP3 CSINM3 BIASOUT PWRGD CSINP2 CSINM2 VID_SEL VCCL3 GATEL3 PGND3 GATEH3 VCCH3 VCCH2 GATEH2 PGND2 GATEL2 5VUVL VCCL1_2 GATEL1 PGND1 GATEH1 VCCH1 NC CSINM1 CSINP1 OVP ENABLE OVPSNS 5VREF VID5 VID0 VID1 VID2 VMAX 30V 30V 30V 0.5V 30V 30V 30V 30V 10V 30V 30V 30V n/a 30V 30V 30V 30V 30V 30V 30V 30V 30V 30V 30V 0.3V 30V 30V 30V 30V 0.3V 30V 30V 30V 30V 0.3V 30V 30V n/a 30V 30V 30V 30V 30V 10V 30V 30V 30V 30V VMIN -0.3V -0.3V -0.5V -0.5V -0.3V -0.3V -0.3V -0.3V -0.3V -0.3V -0.3V -0.3V n/a -0.3V -0.3V -0.3V -0.3V -0.3V -0.3V -0.3V -0.3V -0.3V -0.3V -0.3V DC, -2V for 100ns -0.3V -0.3V DC, -2V for 100ns -0.3V -0.3V -0.3V DC, -2V for 100ns -0.3V -0.3V DC, -2V for 100ns -0.3V -0.3V -0.3V DC, -2V for 100ns -0.3V -0.3V DC, -2V for 100ns -0.3V n/a -0.3V -0.3V -0.3V -0.3V -0.3V -0.3V -0.3V -0.3V -0.3V -0.3V ISOURCE 1mA 1mA 1mA 10mA 1mA 1mA 5mA 1mA 10mA 1mA 5mA 5mA 50mA 1mA 1mA 250mA 250mA 250mA 1mA 250mA 250mA 1mA n/a 3A for 100ns, 200mA DC 3A for 100ns, 200mA DC 3A for 100ns, 200mA DC n/a n/a 3A for 100ns, 200mA DC 3A for 100ns, 200mA DC 3A for 100ns, 200mA DC 1mA n/a 3A for 100ns, 200mA DC 3A for 100ns, 200mA DC 3A for 100ns, 200mA DC n/a n/a 250mA 250mA 1mA 1mA 1mA 10mA 1mA 1mA 1mA 1mA ISINK 1mA 1mA 1mA 10mA 1mA 1mA 5mA 1mA 20mA 1mA 5mA 5mA 1mA 1mA 250mA 1mA 1mA 1mA 20mA 1mA 1mA 1mA 3A for 100ns, 200mA DC 3A for 100ns, 200mA DC n/a 3A for 100ns, 200mA DC 3A for 100ns, 200mA DC 3A for 100ns, 200mA DC 3A for 100ns, 200mA DC n/a 3A for 100ns, 200mA DC 1mA 3A for 100ns, 200mA DC 3A for 100ns, 200mA DC n/a 3A for 100ns, 200mA DC 3A for 100ns, 200mA DC n/a 1mA 1mA 1mA 1mA 1mA 20mA 1mA 1mA 1mA 1mA
o
Page 3 of 39
07/15/04
IR3093
ELECTRICAL SPECIFICATIONS
Unless otherwise specified, these specifications apply over: 7.4V VCC 21V, 4V VCCLX 14V, o o 4V VCCHX 28V, CGATEHX =3.3nF, CGATELX =6.8nF, 0 C TJ 125 C TEST CONDITION -0.3V VOSNS- 0.3V, Connect FB to EAOUT, Measure V(EAOUT) - V(VOSNS-) deviation from Table 1. Applies to all VID codes. RROSC = 47k 9'$& 2&6(7 RROSC = 47k 9'$& 2&6(7 VID_SEL=0, Referenced to VOSNSVID_SEL=Float, Referenced to VOSNSMIN TYP MAX UNIT
PARAMETER VDAC Reference System Set-Point Accuracy Sink Current Source Current VID Input Threshold, INTEL VID Input Threshold, AMD VID_SEL OPTERON Threshold VID_SEL ATHLON Threshold VID_SEL Float Voltage VID_SEL Pull-up Resistance VID_SEL Pull-down Resistance VID Pull-up Current VID Float Voltage VID = 11111 Fault Blanking Error Amplifier Input Offset Voltage FB Bias Current DC Gain Gain-Bandwidth Product Slew Rate Source Current Sink Current Max Voltage Min Voltage VDRP Buffer Amplifier Positioning Offset Voltage Output Voltage Range
0.5 45 48 0.4 1.55 1.0 53 56 0.6 1.65 1.2 3.3 2.6 50 150 18 4.9 2.1 61 64 0.8 1.75 1.4 3.8 3.2 100 350 27 5.2 4.1
% PA V V V V V k k PA V Ps
Tracks ATHLON threshold V(VID_SEL)<2.1V V(VID_SEL)>3.2V VID0-5 = 1V Referenced to LGND Delay to PWRGD assertion Connect FB to EAOUT, Measure V(EAOUT)-V(VDAC). Applies to all VID codes and -0.3V3.0 2.1 30 60 9 4.5 0.5
-5 23.5 90 4 300 .75 4.5
-1 26.4 100 7 1.25 430 1.1 4.9 50 0
3 29.4 105
mV PA dB MHz V/Ps PA mA V mV mV V
600 1.5 5.3 200 125 3.75
V(VDRP) - V(VDAC) with CSINMX=CSINPX=0. Note 1.
-125 0.2
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07/15/04
IR3093
PARAMETER VDRP Buffer Amplifier cont. Source Current Sink Current Oscillator Switching Frequency Phase Shift BIASOUT Regulator SETBIAS Bias Current Set Point Accuracy BIASOUT Dropout Voltage BIASOUT Current Limit Soft Start and Delay SS/DEL to FB Input Offset Voltage Charge Current Hiccup Discharge Current OC Discharge Current Charge/Discharge Current Ratio Charge Voltage Delay Comparator Threshold Discharge Comparator Threshold Over-Current Comparator Input Offset Voltage OCSET Bias Current Max OCSET Set Point Under-Voltage Lockout VCC Start Threshold VCC Stop Threshold VCC Hysteresis 5VUVL Start Threshold 5VUVL Stop Threshold 5VUVL Hysteresis TEST CONDITION MIN 4 200 RROSC = 47k Sequence: GATEH1-GATEH2-GATEH3 RROSC = 47k V(SETBIAS)-V(BIASOUT) @ 100mA I(BIASOUT)=100mA,Threshold when V(SETBIAS)-V(BIASOUT)=0.45V 160 102 94 0.1 1.2 150 With FB = 0V, adjust V(SS/DEL) until EAOUT drives high 0.8 30 3.5 25 9 3.8 190 170 TYP 8 300 200 120 103 0.25 1.8 250 1.1 60 6 55 10 4.0 250 265 MAX 20 650 240 138 117.5 0.55 2.5 450 1.8 90 9 70 13 4.2 300 350 UNIT mA PA kHz PA V V mA V PA PA PA PA/PA V mV mV
Relative to Charge Voltage
V(OCSET)-V(VDAC), CSINM=CSINP1=CSINP2=CSINP3, Note 1. RROSC = 47k
-125 23.5 3.9 7.4 6.9 400 4.05 3.92 100
0 27
125 29.4
mV PA V V V mV V V mV
Start - Stop
Start - Stop
7.9 7.4 540 4.36 4.17 200
8.4 7.9 700 4.55 4.33 250
Page 5 of 39
07/15/04
IR3093
PARAMETER PWRGD Output Output Voltage Leakage Current Enable Input Threshold, INTEL Threshold, AMD Input Resistance Pull-up Voltage Gate Drivers GATEH Rise Time GATEH Fall Time GATEL Rise Time GATEL Fall Time High Voltage (AC) Low Voltage (AC) GATEL low to GATEH high delay GATEH low to GATEL high delay Disable Pull-Down Current PWM Comparator Propagation Delay Common Mode Input Range Internal Ramp Start Voltage Internal Ramp Amplitude Current Sense Amplifier CSINPX Bias Current CSINMX Bias Current Input Current Offset Ratio Average Input Offset Voltage Offset Voltage Mismatch o Gain at TJ = 25 C o Gain at TJ = 125 C Gain Mismatch Differential Input Range Common Mode Input Range TEST CONDITION I(PWRGD) = 4mA V(PWRGD) = 5.5V VID_SEL=0, Referenced to VOSNSVID_SEL=Float, Referenced to VOSNS0.4 1.3 5 2.4 MIN TYP 150 0 0.6 1.5 10 3.0 25 25 50 30 0 0 25 25 35 MAX 400 10 0.8 1.7 20 3.7 50 50 90 60 0.5V 0.5V 50 50 50 UNIT mV PA V V k V ns ns ns ns V V ns ns PA ns V
V mV / %DTC
VCCHX = 8V, Measure 1V to 7V transition time. Note 1. VCCHX = 8V, Measure 7V to 1V transition time. Note 1. VCCLX= 8V, Measure 1V to 7V transition time. Note 1. VCCLX= 8V, Measure 7V to 1V transition time. Note 1. Measure VCCLX- GATELX or VCCHX - GATEHX, Note 1 Measure GATELX or GATEHX, Note 1 VCCHX = VCCLX= 8V, Measure the time from GATELX falling to 1V to GATEHX rising to 1V. Note 1. VCCHX = VCCLX= 8V, Measure the time from GATEHX falling to 1V to GATELX rising to 1V. Note 1. GATHX or GATELX=2V with VCC = 0V. Measure Gate pull-down current Note1
10 10 20
100 0.45 35 -1 -1 0.25 -5 -5 22 18.5 -1 -25 0 0.6 50 0 0 1 0 0 23.5 20.4 0
150 4 0.9 65 1 1 2 5 5 25 21.5 1 75 2.8
(VDRP-VDAC)/GAIN with CSINX=0. Note1 Monitor I(SCOMPX), Note1.
Note 1.
PA PA PA/PA mV mV V/V V/V V/V mV V
Page 6 of 39
07/15/04
IR3093
PARAMETER Share Adjust Error Amplifier Input Offset Voltage MAX Duty Cycle Adjust Ratio MIN Duty Cycle Adjust Ratio Transconductance SCOMPX Source/Sink Current Equal Duty Cycle Comparator Threshold Duty Cycle Match at Startup SCOMPX Precharge Current 0% Duty Cycle Comparator Threshold Voltage Propagation Delay Body Breaking Disable Comparator Threshold OVP VR10.X Comparator Threshold AMD Comparator Threshold Power-up Headroom for OVP Flag OVPSNS Threshold at Powerup SS/DEL Power-up Clear Threshold Propagation Delay OVP Source Current OVP Pull Down Resistance OVP High Voltage OVPSNS Bias Current 5VREF Short Circuit Current Supply Voltage General VCC Supply Current VOSNS- Current VCCHX and VCCL3 Current VCCL1_2 Supply Current 5VUVL Supply Current TEST CONDITION Note 1 Compare Duty Cycle to GATEHX Compare Duty Cycle to GATEHX Note 1 MIN -5 1.5 0.6 100 16 0.45 -5 300 80 TYP 0 2.0 0.5 200 22 0.60 -1 450 130 200 75 MAX 5 UNIT mV PA/V PA V % PA mV ns mV
300 28 0.95 5 700 180 400 110
Compare Duty Cycle to GATEHX V(SS/DEL)=0 Below Internal Ramp1 Start Voltage VCCLX= 8V. Step EAOUT from .8V to .3V and measure time to GATELX transition to < 7V. Compare V(FB) to V(VDAC)
50
VID_SEL=0V. Compare to V(VDAC) Float VID_SEL. Compare to V(VDAC) VCC=OVPSNS where V(OVP)>0.5V. Same for 5VUVL=OVPSNS. VCC=2V, V(OVP) >0.5V. Same for V(5VUVL)=2V. VCC=12V, V(OVPSNS)=1V, VDAC=1.6V, where OVP<0.5V VCCLX= 8V. V(EAOUT)=0V. Step OVPSNS 540mV + V(VDAC). Measure time to GATELX transition to >1V. V(OVP)=0.5V, VCC=1.8V, 5VUVL=0V OVP to LGND I(OVP)=10uA, V(VCC) or V(5VUVL)V(OVP), VCC=1.8V
120 360 0.8 0.3 0.35
150 450 1.1 0.48 0.60 275
200 600 1.8 0.85 0.95 400
mV mV V V V ns PA k V uA mA V mA mA mA mA uA
10 30 0.4 -1 20 4.5 33 3.2 3 6 100
75 60 0.70 0.3 45 5 38 3.7 5 10 200
100 1.1 1.5 60 5.5 44 4.2 7 17 400
I(5VREF)=0A V(VCC)=21V -0.3V VOSNS- 0.3V, All VID Codes V(VCCHX)=28V, V(VCCL3)=14V V(VCCL1_2)=14V V(5VUVL)=5V, no OVP condition
Note 1: Guaranteed by design, but not tested in production Note 2: Critical limits are identified with bold text Note 3: VDAC Output is trimmed to compensate for Error Amp input offsets errors
Page 7 of 39
07/15/04
IR3093
TYPICAL OPERATING CHARACTERISTICS
I(VDAC) Sink and Source Currents vs. ROSC
180 160 140 120 uA 100 80 60 40 20 0 10 20 30 40 50 60 70 80 90 100 110 120 130 ROSC in Kohms I(VDAC) Source Current I(VDAC) Sink Current
I(FB) and I(OCSET) Current vs. ROSC
90 80 70 60 50 I(FB) I(OCSET)
uA
40 30 20 10 0 10 20 30 40 50 60 70 80 90 100 110 120
ROSC (kOhm)
Oscillator freq vs. ROSC
500 450 400
320 300 280 260 240 220 200 180 160 140 120 100 80 60 40 20 10 20 30
I(SETBIAS) vs. ROSC
Frequency (kHz)
350 300 250 200 150 100 50 0 10 20 30 40 50 60 70 80 90 100 110 120
uA
40
50
60
70
80
90
100
110
120
ROSC (kOhm)
Frequency and Bias Current Accuracy vs. ROSC (includes temperature)
6
ROSC (kOhm)
Peak High side Gate drive current vs. Laod capacitance
2.000 1.900 I(GATEHX) in Amps 1.800 1.700 1.600 1.500 1.400 1.300 1.200 1.100 1.000 1 2 3 4 5 6 7 8
I(RISE) I(FALL)
5 +/-3 Sigma V ariation (%)
Frequency
4
VDAC Sink VDAC Source
3
FB Bias OCSET
2
SETBIAS
1 10 20 30 40 50 60 70 80 90 100 ROSC (kOhm)
9
10
C(GATEHX) in nF
Page 8 of 39
07/15/04
IR3093
Peak Low side Gate drive current vs. Laod capacitance
3.250 3.000 I(GATELX) in Amps 2.750 2.500 2.250 2.000 1.750 1.500 1.250 1.000 1 2 3 4 5 6 7 8 9 10 C(GATELX) in nF
I(RISE) I(FALL)
Error Amplifier Frequency Response
180
100
0
-100
93dB DC gain 88 Phase Margin 3.1MHz Crossover
-180 1.0Hz
10Hz
100Hz
1.0KHz
10KHz
100KHz 1.0MHz
10MHz 100MHz
DB(V(comp))
P(V(comp))
Frequency
Page 9 of 39
07/15/04
IR3093 THEORY OF OPERATION
IR OS C
LGND
-
UVL 4 X IROSC
INTERNAL REFERENCE
IROSC
0.48V
SETBIAS
+
BIASOUT
IROSC
AMD=450mV INTEL=150mV VDAC CLK1 CLK2 CLK3 75mV VDAC BB DISABLE Comparator
+
5VUVL 4.36V START 4.17V STOP PWRGD
UVL
+ CLK1 CLK2 CLK3
Oscillator
+
Error_Amp
+
OCSET IAVE
IROSC
OVER CURRENT
+
EQUAL DUTY CYCLE COMPARATOR
+
DELAY
+
250mV
0.6V
H FORCES IROSC/2 AT SS<0.6V
4V
OFF
Sof tStart_Clamp
1.1V
+
-
60U SS ON
+ EAOUT FAULT LATCH S Discharge Comparator
-
6U
55U
Q IN IAVE RESET DOMINANT CLK3 S Q PWM COMPARATOR
-
3V 10k ENABLE
+
+
R SET DOMINANT DAC DEFAULTS TO VR10 WITH VID_SEL GROUNDED F11111 ATHLON_DAC HAMMER_DAC DAC OUT
0.265V
DAC BUFFER
CO3 summer
CO2 summer VD AC
+
IROSC
VO SN S-
AMD=1.5V INTEL=0.6V VOSNSVID_SEL 4.9V 5V 3.3V 1 18uA
VID 0
VID 1
VID 2
VID 3
VID 4
VID 5
X23.5
+ -
X23.5
+ -
X23.5
+ -
3.3V 50K
+
150K
+
1.2V VID0 VID1 VID2 VID3 VID4 VID5 VOSNSVDAC CSINM3 CSINP3 CSINM2 CSINP2 CSINM1 CSINP1
-
-
+DISABLE
-
7.9V START 7.4V STOP
1.243
+
-
+
VCC
5VREF
ROSC
FB
OVPSNS
STARTUP OVP Comparator 75U VCC ON 75U 5VUVL
OVP 60k DRIVE IN RESET DOMINANT CLK1 S Q PWM COMPARATOR EAOUT QB R
+
-
-
+
-
-
Page 10 of 39 Figure 1 - IR3093 Block Diagram 07/15/04
VCCH1
GATEHI OL_OUT PGND
GATEH1
OVP Comparator
OL_IN GateHI
PGND1
RSFF DRIVE IROSC/2 OL_IN IN 0.6V GateLO PGND OL_OUT GATELO VCCL1_2
9p
GATEL1
VCCH2 DRIVE 0% DUTY CYCLE 0.47V RESET DOMINANT CLK2 S Q PWM COMPARATOR
+
IN OL_IN GateHI PGND
GATEHI OL_OUT
GATEH2
R RSFF
QB
PGND2
DRIVE IROSC/2 CO1
PRESET
OL_IN IN
OL_OUT GATELO PGND
+ 9p CO2 0 TO IROSC*3/4 Share Adjust Error Amp
0.6V
GATEL2
GateLO
SCOMP2
VCCH3 DRIVE GATEHI OL_OUT PGND PGND3 GATEH3
OL_IN GateHI
CO1 summer Share Adjust Error Amp CO1 CO3 VD AC
+
R RSFF
QB
IROSC OL_IN IN 0.6V GateLO
DRIVE OL_OUT GATELO PGND
VCCL3
VD AC
+ -
PRESET
9p 0 TO IROSC*3/4
GATEL3
SCOMP3
VDRP
IR3093
IR3093
PWM Operation The IR3093 is a fully integrated 3 phase interleaved PWM control IC which uses voltage mode control with trailing edge modulation. A high-gain wide-bandwidth voltage type Error Amplifier in the Control IC is used for the voltage control loop. The PWM block diagram of the IR3093 is shown in Figure 2.
U30
IROSC
CLK1 CLK2 CLK3
RSFF S CLK2 CLK3 PWM COMPARATOR
+
Q
OSCBLOCK
+
QB R RESET DOMINANT GATEH1 IROSC/2
VIN
OVPSNS
80mV VDAC
BB DISABLE GATEL1 9p 0.6V
CDAC RDAC VOSNSVDAC ERROR AMPLIFIER
+ +
FB
0.47V IROSC
0% DUTY CYCLE CLK2 PWM COMPARATOR
-
CCOMP RCOMP EAOUT
VDRP BUFFER RDRP VDRP
+
Share Adjust Error Amp
+ 0 TO IROSC*3/4
RFB SCOMP2
CSC2 CLK3 RSC2 PWM COMPARATOR EAOUT
+
Share Adjust Error Amp
+ SCOMP3 0 TO IROSC*3/4
CSC3
RSC3
Figure 2 - PWM Block Diagram Refer to Figure 3. Upon receiving a clock pulse, the RSFF is set, the internal PWM ramp voltage begins to increase, the low side driver is turned off, and the high side driver is then turned on. For phase 1, an internal 9pf capacitor is charged by a current source that proportional to the switching frequency resulting in a ramp rate of 50mV per percent duty cycle. For example, if the steady-state operating switch node duty cycle is 10%, then the internal ramp amplitude is typically 500mV from the starting point (or floor) to the crossing of the EAOUT control voltage. When the PWM ramp voltage exceeds the Error Amplifier's output voltage, the RSFF is reset. This turns off the high side driver, turns on the low side driver, and discharges the PWM ramp to 0.6V until the next clock pulse.
Page 11 of 39
-
-
1 RCS1
2 CCS1
RSFF S Q GATEH2
VIN VOUT SENSE+ 1 GATEL2 RCS2 CCS2 2 VOUT+ COUT VOUTVOUT SENSE-
+
QB R RESET DOMINANT IROSC
-
9p
0.6V
RSFF S Q GATEH3
VIN
QB R RESET DOMINANT IROSC
1 GATEL3 RCS3
2
CCS3
9p
0.6V
VDAC X23.5 CSINM3
+
CSINP3
VDAC X23.5 CSINM2
+
CSINP2
VDAC X23.5 CSINM1
+
CSINP1
07/15/04
IR3093
50% INTERNAL OSCILLATOR RAMP DUTY CYCLE
CLK1
CLK2
CLK3
RAMP3 MIN DUTY CYCLE ADJUST RAMP3 FIXED RAMP1 RAMP2
RAMP3 MAX DUTY CYCLE ADJUST
EAOUT
0.6V RAMP1 SLOPE = 50mV / % DC THE SHARE ADJUST ERROR AMPLIFIER CAN CHANGE THE PULSE WIDTH OF RAMPS 2 & 3 FROM 0.5 x RAMP1 TO 2.0 X RAMP1 TO FORCE CURRENT SHARING.
Figure 3 - 3 Phase Oscillator and PWM Waveforms The RSFF is reset dominant allowing both phases to go to zero duty cycle within a few tens of nanoseconds in response to a load step decrease. Phases can overlap and go to 100% duty cycle in response to a load step increase with turn-on gated by the clock pulses. An Error Amplifier output voltage greater than the common mode input range of the PWM comparator results in 100% duty cycle regardless of the voltage of the PWM ramp. This arrangement guarantees the Error Amplifier is always in control and can demand 0 to 100% duty cycle as required. It also favors response to a load step decrease which is appropriate given the low output to input voltage ratio of most systems. The inductor current will increase much more rapidly than decrease in response to load transients. This control method is designed to provide "single cycle transient response" where the inductor current changes in response to load transients within a single switching cycle maximizing the effectiveness of the power train and minimizing the output capacitor requirements. Body Braking
TM
In a conventional synchronous buck converter, the minimum time required to reduce the current in the inductor in response to a load step decrease is; TSLEW = [L x (IMAX - IMIN)] / Vout The slew rate of the inductor current can be significantly increased by turning off the synchronous rectifier in response to a load step decrease. The switch node voltage is then forced to decrease until conduction of the synchronous rectifier's body diode occurs. This increases the voltage across the inductor from Vout to Vout + VBODY DIODE. The minimum time required to reduce the current in the inductor in response to a load transient decrease is now; TSLEW = [L x (IMAX - IMIN)] / (Vout + VBODY DIODE)
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Since the voltage drop in the body diode is often higher than output voltage, the inductor current slew rate can be increased by 2X or more. This patent pending technique is referred to as "body braking" and is accomplished through the "0% Duty Cycle Comparator". If the Error Amplifier's output voltage drops below 0.47V, this comparator turns off the low side gate driver. Figure 4 depicts PWM operating waveforms under various conditions
CLK1 PULSE
EAOUT PWM Ramp1 0.6V 0.47V
GATEH1
GATEL1
STEADY-STATE OPERATION
DUTY CYCLE INCREASE DUE TO LOAD INCREASE
DUTY CYCLE DECREASE DUE TO LOAD DECREASE (BODY BRAKING) OR FAULT
STEADY-STATE OPERATION
Figure 4 - PWM Operating Waveforms Current Sense Amplifier A high speed differential current sense amplifier is shown in Figure 5. Its gain decreases with increasing temperature and is nominally 23.5 at 25C and 20.4 at 125C (-1400 ppm/C). This reduction of gain tends to compensate the 3850 ppm/C increase in inductor DCR. Since in most designs the IR3093 IC junction is hotter than the inductors these two effects tend to cancel such that no additional temperature compensation of the load line is required. The current sense amplifier can accept positive differential input up to 75mV and negative up to -25mV before clipping. The output of the current sense amplifier is summed with the DAC voltage which is used for over current protection, voltage positioning and current sharing.
vL iL L Rs CSA RL Cs vc Vo Co
CO
Figure 5 - Inductor Current Sensing and Current Sense Amplifier
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VCC Under Voltage Lockout (UVLO) The VCC UVLO function monitors the IR3093's VCC supply pin and ensures enough voltage is available to power the internal circuitry. During power-up the fault latch is reset when VCC exceeds 7.9V and all other faults are cleared. The fault latch is set when VCC drops below 7.4V and SS/DEL is below 3.75V. 5VUVL Under Voltage Lockout (5VUVL) The 5VUVL function is provided for converters using a separate voltage supply other than VCC for gate driver bias. The 5VUVL comparator prevents operation by discharging SS/DEL below 3.75V to force EAOUT low. The 5VUVL comparator has an OK threshold of 4.36V ensuring adequate gate drive voltage is present and a fault threshold of 4.17V. Power Good Output The PWRGD pin is an open-collector output and should be pulled up to a voltage source through a resistor. During soft start, the PWRGD remains low until the output voltage is in regulation and SS/DEL is above 3.75V. The PWRGD pin becomes low if the fault latch is set. A high level at the PWRGD pin indicates that the converter is in operation and has no fault, but does not ensure the output voltage is within the specification. Output voltage regulation within the design limits can logically be assured however, assuming no component failure in the system. Tri-State Gate Drivers The GATELX drivers can pull down up to 3.5A peak current and source up to 1.5A. The GATEHX drivers can source and sink up to 1.5A peak current. An adaptive non-overlap circuit monitors the voltage on the GATEHX and GATELX pins to prevent MOSFET shoot-through current while minimizing body diode conduction. The Error Amplifier output of the Control IC drives low in response to any fault condition such as VCC input under voltage or output overload. The 0% duty cycle comparator detects this and drives both gate outputs low. This tri-state operation prevents negative inductor current and negative output voltage during power-down. The Gate Drivers revert to a high impedance "off" state at VCCLX and VCCHX supply voltages below the normal operating range. An 80k UHVLVWRU LV FRQQHFWHG DFURVV WKH *$7(; DQG 3*1'; SLQV WR SUHYHQW WKH *$7(; YROWDJH from rising due to leakage or other cause under these conditions. Over Voltage Protection (OVP) The output Over-Voltage Protection comparator monitors the output voltage through the OVPSNS pin, the positive remote sense point. If OVPSNS exceeds VDAC plus 150mV (for VR-10.0, 450mV for OPTERON and ATHLON, selected with the VID_SEL pin), both GATEL pins drive high and the OVP pin sources 75uA current. The OVP circuit over-rides the normal PWM operation and will fully turn-on the low side MOSFET within approximately 150ns. The low side MOSFET will remain ON until the over-voltage condition ceases. The lower MOSFETs alone can not clamp the output voltage however an SCR or N-MOSFET could be triggered with the OVP pin to prevent processor damage. In the event of a high side MOSFET short, the OVP flag is activated with as little supply voltage as possible. The OVPSNS pin is compared against both VCC and 5VUVL for OVP conditions at power-up. VCC is monitored for conversion off 12V, 5VUVL is monitored for conversion off 5V. The OVP pin flags a voltage greater than 0.5V with supply voltages as low as 1.0V. This headroom voltage varies inversely with temperature. An external comparator can be used to disable the silver box, activate a crowbar, or supply source. The overall system must be considered when designing for OVP. In many cases the over-current protection of the ACDC or DC-DC converter supplying the multiphase converter will be triggered thus providing effective protection without damage as long as all PCB traces and components are sized to handle the worst-case maximum current. If this is not possible, a fuse can be added in the input supply to the multiphase converter.
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A Body Braking Disable Comparator has been included to prevent false OVP firing during dynamic VID down TM changes. The BB DISABLE Comparator disables Body Braking when FB exceeds VDAC by 75mV. The low side MOSFETs will then be controlled to keep V(FB) and V(VOUT) within 80mV of V(VDAC), below the 150mV INTEL OVP trip point.
TM
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APPLICATIONS INFORMATION
VIN CIN VIN ENABLE OVP C5VREF VID5 VID0 VID1 VID2 VID3 VID4 RROSC CBST1 1 RCS1 CCS1 2 VOUT SENSE+ VOUT+
GNDIN
COUT U13 VID2 VID1 VID0 VID5 5VREF OVPSNS ENABLE OVP CSINP1 CSINM1 NC VCCH1 VIN VOUTVOUT SENSE-
CDAC RFB RDAC RDRP
ROCSET
RCOMP
CCOMP CSC2 CSC3 CSS CsenseRSC2 RSC3
LGND SETBIAS VCC CSINP3 CSINM3 BIASOUT PWRGD CSINP2 CSINM2 VID_SEL VCCL3 GATEL3
VID3 VID4 ROSC VOSNSOCSET VDAC VDRP FB EAOUT SS/DEL SCOMP2 SCOMP3
IR3093
48LD MLPQ
GATEH1 PGND1 GATEL1 VCCL1_2 5VUVL GATEL2 PGND2 GATEH2 VCCH2 VCCH3 GATEH3 PGND3
CBST2
1 RCS2
2
CCS2
VIN CBIAS
RSET
VIN CVCC
IR3093
CBST3
1 RCS3
2
CCS3
POWERGOOD
Figure 6 - System Diagram
VID Control The IR3093 provides three different microprocessor solutions. The VID_SEL pin selects the appropriate Digital-toAnalog Converters (DAC), VID threshold voltages, and Over Voltage Protection (OVP) threshold for either VR-10.0, OPTERON, or ATHLON solutions. Reference voltages are shown in Table 1. The DAC output voltage is available at the VDAC pin. A detailed block diagram of the VID control circuitry can be found in Figure 7. The VID pins are internally pulled up to 4.9V by 18uA current sources. The VID input comparators have a 0.6V threshold for VR-10.0 or 1.65V threshold for OPTERON and ATHLON. The selected DAC voltage is provided at the Error Amplifier positive input and to the VDAC pin by the trans-conductance DAC Buffer. The VDAC voltage is trimmed to the Error Amplifier output voltage with EAOUT tied to FB via an accurate resistor. This compensates DAC Buffer input offset, Error Amplifier input offset, and errors in the generation of the FB bias current which is based on RROSC. This trim method provides a 0.5% system accuracy. The IR3093 can accept changes in the VID code while operating and vary the VDAC voltage accordingly. The IR3093 detects a VID change and blanks the DAC output response for 400ns to verify the new code is valid and not due to skew or noise. The sink/source capability of the VDAC buffer amp is programmed by the same external resistor that sets the oscillator frequency, RROSC. The slew rate of the voltage at the VDAC pin can be adjusted by an external capacitor between VDAC pin and the VOSNS- pin. A resistor connected in series with this capacitor is Page 16 of 39 07/15/04
IR3093
required to compensate the VDAC buffer amplifier. Digital VID transitions result in a smooth analog transition of the VDAC voltage and converter output voltage minimizing inrush currents in the input and output capacitors and overshoot of the output voltage.
18uA
4.9V
VID=11111X FAULT BLANKING, 3.3us DIGITAL TO ANALOG CONVERTER
TO FAULT
VID5 VID0 VID1 VID2 VID3 VID4
VID INPUT COMPARATORS (1 OF 6 SHOWN)
SHOWN DEFAULT TO VR10 WITH VID_SEL GROUNDED
+ -
"SLOW" VDAC DAC BUFFER
VDAC
"FAST" VDAC DAC DEFAULTS TO VR10 WITH VID_SEL GROUNDED
+
IROSC
HAMMER DAC
0.6V
1.65V
5V 2.6V FLOAT VOLTAGE 3.3V
+
H=OPTERON
50K
150K
1.2V
VID_SEL
H=ATHLON
3.3V
VOSNS-
Figure 7- VID Control Block Diagram
VID = 11111X Fault VID codes of 111111 and 111110 will set the fault latch and disable the Error Amplifier once SS/DEL is below 3.75V.
Page 17 of 39
ATHLON DAC
+ -
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IR3093
AMD Opteron VID Table VID_SEL Open. V(VDAC) is prepositioned 50mV higher than Vout values listed below for load positioning. Vout is measured at EAOUT with ROSC=47K and a 1890 ohm resistor connecting FB to EAOUT to cancel the 50mV pre-position offset. Vout VID4 VID3 VID2 VID1 VID0 (V) 0 0 0 0 0 1.550 0 0 0 0 1 1.525 0 0 0 1 0 1.500 0 0 0 1 1 1.475 0 0 1 0 0 1.450 0 0 1 0 1 1.425 0 0 1 1 0 1.400 0 0 1 1 1 1.375 0 1 0 0 0 1.350 0 1 0 0 1 1.325 0 1 0 1 0 1.300 0 1 0 1 1 1.275 0 1 1 0 0 1.250 0 1 1 0 1 1.225 0 1 1 1 0 1.200 0 1 1 1 1 1.175 1 0 0 0 0 1.150 1 0 0 0 1 1.125 1 0 0 1 0 1.100 1 0 0 1 1 1.075 1 0 1 0 0 1.050 1 0 1 0 1 1.025 1 0 1 1 0 1.000 1 0 1 1 1 0.975 1 1 0 0 0 0.950 1 1 0 0 1 0.925 1 1 0 1 0 0.900 1 1 0 1 1 0.875 1 1 1 0 0 0.850 1 1 1 0 1 0.825 1 1 1 1 0 0.800 4 1 1 1 1 1 OFF Note: 4 Output disabled (Fault mode) Table 1 - Voltage Identification (VID) AMD ATHLON VID Table VIDSEL to VCC. V(VDAC) is prepositioned 50mV higher than Vout values listed below for load positioning. Vout is measured at EAOUT with ROSC=47K and a 1890 ohm resistor connecting FB to EAOUT to cancel the 50mV pre-position offset. Vout VID4 VID3 VID2 VID1 VID0 (V) 0 0 0 0 0 1.850 0 0 0 0 1 1.825 0 0 0 1 0 1.800 0 0 0 1 1 1.775 0 0 1 0 0 1.750 0 0 1 0 1 1.725 0 0 1 1 0 1.700 0 0 1 1 1 1.675 0 1 0 0 0 1.650 0 1 0 0 1 1.625 0 1 0 1 0 1.600 0 1 0 1 1 1.575 0 1 1 0 0 1.550 0 1 1 0 1 1.525 0 1 1 1 0 1.500 0 1 1 1 1 1.475 1 0 0 0 0 1.450 1 0 0 0 1 1.425 1 0 0 1 0 1.400 1 0 0 1 1 1.375 1 0 1 0 0 1.350 1 0 1 0 1 1.325 1 0 1 1 0 1.300 1 0 1 1 1 1.275 1 1 0 0 0 1.250 1 1 0 0 1 1.225 1 1 0 1 0 1.200 1 1 0 1 1 1.175 1 1 1 0 0 1.150 1 1 1 0 1 1.125 1 1 1 1 0 1.100 4 1 1 1 1 1 OFF
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INTEL VR-10.0 VID Table (VID_SEL Grounded, measured at EAOUT=FB. ) Processor Pins (0 = low, 1 = high) Processor Pins (0 = low, 1 = high) Vout
VID4 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 1 1 1 VID3 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 1 1 1 VID2 0 0 0 0 0 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 0 0 0 VID1 1 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 VID0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 VID5 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 (V) 0.8375 0.8500 0.8625 0.8750 0.8875 0.9000 0.9125 0.9250 0.9375 0.9500 0.9625 0.9750 0.9875 1.0000 1.0125 1.0250 1.0375 1.0500 1.0625 1.0750 1.0875 4 OFF 4 OFF 1.1000 1.1125 1.1250 1.1375 1.1500 1.1625 1.1750 1.1875 1.2000 VID4 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 0 VID3 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 1 1 1 VID2 0 0 0 0 0 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 0 0 0 VID1 1 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 VID0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 VID5 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 Vout (V) 1.2125 1.2250 1.2375 1.2500 1.2625 1.2750 1.2875 1.3000 1.3125 1.3250 1.3375 1.3500 1.3625 1.3750 1.3875 1.4000 1.4125 1.4250 1.4375 1.4500 1.4625 1.4750 1.4875 1.5000 1.5125 1.5250 1.5375 1.5500 1.5625 1.5750 1.5875 1.6000
Note: 4. Output disabled (Fault mode) Table 1 Continued - Voltage Identification (VID)
Slew Rate Programming Capacitor CDAC and Resistor RDAC VDAC sink current ISINK and source current ISOURCE are determined by RROSC, and their value can be found using the curve in this data sheet. The slew rate of VDAC down-slope SRDOWN can be programmed by the external capacitor CDAC as defined in Equation (1) and shown in Figure1. Resistor RDAC is used to compensate VDAC circuit and is determined by Equation (2). The slew rate of VDAC up-slope SRUP is proportional to the down-slope slew rate SRDOWN and is given by Equation (3).
C DAC
I SINK SRDOWN
(1)
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R DAC
SRUP
C DAC
2
I SOURCE C DAC
Oscillator Resistor RROSC The oscillator frequency is programmable from 100kHz to 540kHz with an external resistor RROSC as shown in Figure 6 oscillator generates an internal 50% duty cycle sawtooth signal (Figure 3.) that is used to generate 120 out-of-phase timing pulses to set Phase 1,2 and 3 RS flip-flops. Once the switching frequency is chosen, RROSC can be determined from the curve in the Typical Operating Characteristics Section. Soft Start, Over-Current Fault Delay, and Hiccup Mode The IR3093 has a programmable soft-start function to limit the surge current during converter power-up. A capacitor connected between the SS/DEL and LGND pins controls soft start timing as well as over-current protection delay and hiccup mode timing. Figure 8 depicts the various operating modes of the SS/DEL function. Under a no fault condition, the SS/DEL capacitor will charge. The SS/DEL charge soft-start duration is controlled by a 60uA charge current which charges CSS up to 4.0V. The Error Amplifier output is clamped low until SS/DEL reaches 1.1V. The Error Amplifier will then regulate the converter's output voltage to match the SS/DEL voltage less the 1.1V offset until it reaches the level determined by the VID inputs. The PWRGD signal is asserted once the SS/DEL voltage exceeds 3.75V. Five different faults will immediately cause SS/DEL to begin discharging and set the Fault Latch once SS/DEL is below 3.75V; 1. 2. 3. 4. 5. VCC Under Voltage Lock Out 5VUVL Under Voltage Lock Out VID=11111x fault Low Enable pin Over Current Condition.
A delay is included if any fault condition occurs after a successful soft start sequence. This is required since momentary faults can occur as part of normal operation due to load transients such as exciting an over-current condition or a VID=11111x code while going through VID transitions. If any fault occurs during normal operation, the SS/DEL capacitor will discharge through a 55uA current sink but will not set the fault latch immediately. If the fault condition persists long enough for the SS/DEL capacitor to discharge below the 3.75V threshold of the delay comparator, the Fault latch will be set pulling the Error Amplifier's output low, inhibiting switching and de-asserting the PWRGD signal. The SS/DEL capacitor is then discharged through a 6uA discharge current resulting in a long hiccup duration. The SS/DEL capacitor will continue to discharge until it reaches 0.265V where the fault latch is reset allowing a normal soft start to occur. If a fault condition is again encountered during the soft start cycle, the fault latch will be set without any delay and hiccup mode will begin. During hiccup mode the 10 to 1 charge to discharge ratio results in a 9.1% hiccup mode duty cycle regardless of at what point a fault condition occurs. The converter can be disabled if the SS/DEL pin is pulled below 0.9V.
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0.5
3.2 10
15
(2) (3)
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IR3093
VCC (12V) 4.36V 5VUVL 3.75V 1.1V 7.4V UVLO
SS/DEL
VOUT
PWRGD
OCP THRESHOLD IOUT START-UP (5VUVL GATES FAULT MODE) NORMAL OPERATION (VOUT CHANGES DUE TO LOAD AND VID CHANGES) OCP DELAY HICCUP OVER-CURRENT PROTECTION RE-START AFTER OCP CLEARS POWER-DOWN (VCC GATES FAULT MODE)
Figure 8 - Operating Waveforms Soft-start delay time tSSDEL is the time SS/DEL charged up to 1.1V. After that the error amplifier output is released to allow the soft start. The soft start time tSS represents the time during which converter output voltage rises from zero to VO. tSS can be programmed by CSS using equation (4).
C SS
Once CSS is chosen, the soft start delay time tSSDEL, the over-current fault latch delay time tOCDEL, and the delay time tVccPG from output voltage (VO) in regulation to Power Good are fixed and shown in equation (5), (6) and (7) respectively.
Over Current Protection (OCP) The current limit threshold is set by a resistor connected between the OCSET and VDAC pins. If the average Current Sense Amplifier output plus VDAC voltage exceeds the OCSET voltage, the over-current protection is triggered.
Page 21 of 39
tVccPG
C SS * 'V I CHG
C SS * (3.75 VO 1.1) 60 *10 6
t OCDEL
C SS * 'V I DISCHG
C SS * 0.25 61*10 6
t SSDEL
C SS * 'V I CHG
C SS *1.1 60 *10 6
I CHG * t SS VO
60 *10 6 * t SS VO
(4)
(5)
(6)
(7)
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IR3093
A delay is included if an over-current condition occurs after a successful soft-start sequence. This is required since over-current conditions can occur as part of normal operation due to load transients or VID transitions. If an overcurrent fault occurs during normal operation, the Over Current Comparator will initiate the discharge of the capacitor at SS/DEL but will not set the fault latch immediately. If the over-current condition persists long enough for the SS/DEL capacitor to discharge below the 250mV offset of the delay comparator, the Fault latch will be set pulling the Error Amplifier's output low inhibiting switching in the phase ICs and de-asserting the PWRGD signal. See Soft Start, Over-Current Fault Delay, and Hiccup Mode. The hiccup mode duty cycle of over current protection is determined by the ratio of the charge to discharge current and is fixed at 9.1% for the ratio of 10 to 1. The inductor DC resistance RL is utilized to sense the inductor current. The current limit threshold is set by a resistor ROCSET connected between the OCSET and VDAC pins, as shown in Fig1. ILIMIT is the required over current limit. IOCSET, the bias current of OCSET pin, is set by RROSC and is determined by the curve in this data sheet. OCP need to satisfy the high temperature condition. RL_MAX and RL_ROOM are the inductor DCR at maximum temperature TL_MAX and room temperature T_ROOM respectively, the maximum inductor DCR can be calculated from Equation (8)
RL _ MAX
RL _ ROOM [1 3850 *10 6 (TL _ MAX TROOM )]
(8)
The current sense amplifier gain of IR3093 decreases with temperature at the rate of1400 PPM, which compensates part of the inductor DCR increase. The minimum current sense amplifier gain at the maximum IC temperature TIC_MAX is calculated from Equation (9).
|
GCS _ MIN
GCS _ ROOM [1 1400 *10 6 (TIC _ MAX TROOM )]
I LIMIT 'I ) RL _ MAX ] GCS _ MIN / I OCSET 3 2
(9)
ROCSET can be calculated by the following equation (10), where I is the ripple current in each output inductor.
ROCSET
[(
(10)
'I
Adaptive Voltage Positioning
Vo (Vin Vo) L Vin fsw
(11)
Adaptive voltage positioning is needed to reduce output voltage deviations during load transients and power dissipation of the load when it is drawing maximum current. The circuitry related to voltage positioning is shown in Figure 8. Resistor RFB is connected between the Error Amplifier's inverting input pin FB and the converter's output voltage. An internal current source whose value is programmed by the same external resistor that programs the oscillator frequency, RROSC, pumps current out of the FB pin. The FB bias current develops a positioning voltage drop across RFB which forces the converter's output voltage lower to V(VDAC)-I(FB)* RFB to maintain a balance at the Error Amplifier inputs. RFB is selected to program the desired amount of fixed offset voltage below the DAC voltage. The voltage at the VDRP pin is an average of three phase Current Sense Amplifiers and represents the sum of the VDAC voltage and the average inductor current of all the phases. The VDRP pin is connected to the FB pin through the resistor. The Error Amplifier forces the voltage on the FB pin to equal VDAC through the power supply loop therefore the current through RDRP is equal to (VDRP-VDAC) / RDRP. As the load current increases, the VDRP voltage increases accordingly which results in an increase RFB current, further positioning the output regulated voltage lower thus making the output voltage reduction proportional to an increase in load current. The droop impedance or output impedance of the converter can thus be programmed by the resistor RDRP. The offset and slope of the converter output impedance are independent of the VDAC voltage.
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AMD specifies the acceptable power supply regulation window as 50mV around their specified VID tables. VR10.0 specifies the VID table voltages as the absolute maximum power supply voltage. In order to have all three DAC options, the OPTERON and ATHLON DAC output voltages are pre-positioned 50mV higher than listed in AMD specs. During testing, a series resistor is placed between EAOUT and FB to cancel the additional 50mV out of the DAC. The FB bias current, equal to IROSC, develops the 50mV cancellation voltage. Trimming the VDAC voltage by monitoring V(EAOUT) with this 50mV cancellation resistor in circuit also trims out errors in the FB bias current. The VDRP pin voltage represents the average current of the converter plus the DAC voltage. The load current can be retrieved by subtracting the VDAC voltage from the VDRP voltage.
VDAC CDAC RDAC VOSNSVDAC ERROR AMPLIFIER
+
FB
RCOMP
IROSC
CCOMP
EAOUT
IROSC IDRP RDRP - V(CSav g) + VDRP BUFFER VDRP
+
+ VPOSITIONING VOUT SENSE+ RFB VOUT SENSE-
Figure 9 - Adaptive voltage positioning A resistor RFB between FB pin and the converter output is used to create output voltage offset VO_NLOFST which is the difference between VDAC voltage and output voltage at no load condition. An internal current source whose value is programmed by the same external resistor that programs the oscillator frequency, RROSC, pumps current IFB out of the FB pin. The VDRP pin is connected to the FB pin through the Adaptive Voltage Positioning Resistor RDRP. Adaptive voltage positioning lowers the converter voltage by RO*IO, where RO is the required output impedance of the converter. RFB and RDRP are determined by (12) and (13) respectively, where RO is the required output impedance of the converter.
RFB
Page 23 of 39
-
VDAC X23.5 CSINM3 CSINP3
+
VDAC X23.5 CSINM2 CSINP2
+
-
VDAC X23.5 CSINM1 CSINP1
+
VO _ NLOFST I FB
(12)
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IR3093
R DRP R FB R L _ MAX GCS _ MIN n RO
(13)
Lossless Average Inductor Current Sensing Inductor current can be sensed by connecting a series resistor and a capacitor network in parallel with the inductor and measuring the voltage across the capacitor. The equation of the sensing network is,
vC ( s )
v L ( s)
1 1 sRS C S
i L ( s)
R L sL 1 sRS C S
Usually the resistor Rcs and capacitor Ccs are chosen so that the time constant of Rcs and Ccs equals the time constant of the inductor which is the inductance L over the inductor DCR. If the two time constants match, the voltage across Ccs is proportional to the current through L, and the sense circuit can be treated as if only a sense resistor with the value of RL was used. The mismatch of the time constants does not affect the measurement of inductor DC current, but affects the AC component of the inductor current. The advantage of sensing the inductor current versus high side or low side sensing is that actual output current being delivered to the load is obtained rather than peak or sampled information about the switch currents. The output voltage can be positioned to meet a load line based on real time information. Except for a sense resistor in series with the inductor, this is the only sense method that can support a single cycle transient response. Other methods provide no information during either load increase (low side sensing) or load decrease (high side sensing). An additional problem associated with peak or valley current mode control for voltage positioning is that they suffer from peak-to-average errors. These errors will show in many ways but one example is the effect of frequency variation. If the frequency of a particular unit is 10% low, the peak to peak inductor current will be 10% larger and the output impedance of the converter will drop by about 10%. Variations in inductance, current sense amplifier bandwidth, PWM prop delay, any added slope compensation, input voltage, and output voltage are all additional sources of peak-to-average errors. Measure the inductance L and the inductor DC resistance RL. Pre-select the capacitor CCS and calculate RCSX as follows.
RCSX
L RL CCS
(14)
Inductor DCR Temperature Correction If the Current Sense Amplifier temperature dependent gain is not adequate to compensate the inductor DCR TC, a negative temperature coefficient (NTC) thermistor can be added. The thermistor should be placed close to the inductor and connected in parallel with the feedback resistor, as shown in Figure 9. The resistor in series with the thermistor is used to reduce the nonlinearity of the thermistor.
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VDAC
VDAC VOSNS-
ERROR AMPLIFIER
+
EAOUT
FB
IROSC VDRP BUFFER VDRP
+
RDRP
VOUT SENSE+ RFB
RLINEAR
RNTC
Figure 10 - Temperature compensation of inductor DCR Remote Voltage Sensing To compensate for impedance in the ground plane, the VOSNS- pin is used for remote sensing and connects directly to the load. The VDAC voltage is referenced to VOSNS- to avoid additional error terms or delay related to a separate differential amplifier. The capacitor connecting the VDAC and VOSNS- pins ensure that high speed transients are fed directly into the Error Amplifier without delay. Master-Slave Current Share Loop Current sharing between phases of the converter is achieved by a Master-Slave current share loop topology. The output of the Phase 1 Current Sense Amplifier sets the reference for the Share Adjust Error Amplifiers. Each Share Adjust Error Amplifier adjusts the duty cycle of its respective PWM Ramp and to force its input error to zero compared to the master Phase 1, resulting in accurate current sharing. The maximum and minimum duty cycle adjust range of Ramps 2 & 3 compared to Ramp1 has been limited to a minimum of 0.5x and a maximum of 2.0x typical (see Figure 3.). The crossover frequency of the current share loop can be programmed with a capacitor at the SCOMPX pin so that the share loop does not interact with the output voltage loop. The SCOMPX capacitor is driven by a trans-conductance stage capable of sourcing and sinking 22uA. The duty cycle of Ramps 2 & 3 inversely tracks the voltage on their SCOMPX pin; if V(SCOMP2) increases, Ramp2's slope will increase and the effective duty cycle will decrease resulting in a reduction in Phase 2's output current. Due to the limited 22uA source current, an SCOMPX pre-charge circuit has been included to pre-condition V(SCOMPX) so that the duty cycle of Ramps 2 & 3 are equal to Ramp1 prior to any GATEHX high pulses. The pre-condition circuit can source 450uA. The Equal Duty Cycle Comparator (see Block Diagram) activates a pre-charge circuit when SS/DEL is less than 0.6V. The Error Amplifier becomes active enabling GATEH switching when SS/DEL is above 1.1V. Set BIASOUT voltage BIASOUT pin provides 150mA open-looped regulated voltage for GATE drive bias, and the voltage is set by SETBIAS through an external resistor Rset connecting between SETBIAS pin and ground. Bias current ISETBIAS is a function of ROSC. Rset is chosen by equation (15). VFD in the equation is the forward voltage drop across the Bootstrap diode.
Page 25 of 39
-
-
Current + VDAC
07/15/04
IR3093
RSET
Compensation of the Current Share Loop The crossover frequency of the current share loop should be at least one decade lower than that of the voltage loop in order to eliminate the interaction between the two loops. A 22nF capacitor from SCOMP to LGND is good for most of the applications. If necessary have a 1k resistor in series with the Csc to make the current loop a little bit faster. Compensation of Voltage Loop The adaptive voltage positioning is used in the computer applications to meet the load line requirements. Like current mode control, the adaptive voltage positioning loop introduces extra zero to the voltage loop and splits the double poles of the power stage, which make the voltage loop compensation much easier. Resistors RFB and RDRP are chosen according to Equations (12) and (13), and the selection of compensation types depends on the capacitors used. For the applications using Electrolytic, Polymer or AL-Polymer capacitors, type II compensation shown in Figure 11 (a) is usually enough. While for the applications with only low ESR ceramic capacitors, type III compensation shown in Figure 11 (b) is preferred.
CCP1
V BIASOUT VFD I SETBIAS
(15)
CCP1
VO+
RFB
RCOMP
CCOMP
RCOMP
CCOMP
RFB1
CFB
FB
EAOUT EAOUT
VO+
RFB
FB
EAOUT EAOUT
VDRP
RDRP
VDAC
+
VDRP
RDRP
VDAC
+
CDRP
(a) Type II compensation
(b) Type III compensation
Figure 11 . Voltage loop compensation network Type II Compensation Determine the compensation at no load, the worst case condition. Assume the time constant of the resistor and capacitor across the output inductors matches that of the inductor, the crossover frequency of the voltage loop can be estimated by Equations (16), where CE and RCE are the equivalent capacitance and ESR of output capacitors respectively and RLE is the equivalent resistance of inductor DCR.
fC
R DRP 2S * C E (GCS * R FB R LE RCE )
(16)
RCOMP and CCOMP have limited effect on the crossover frequency, and are used only to fine tune the crossover frequency and transient load response. Choose the desired crossover frequency fc1 around fc estimated by Equation (16) and determine RCOMP and CCOMP.
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IR3093
RCOMP (2S f C1 ) 2 LE C E R FB V IN FM
10 L E C E RCOMP
(17)
C COMP
(18)
CCP1 is optional and may be needed in some applications to reduce the jitter caused by the high frequency noise. A ceramic capacitor between 10pF and 220pF is usually enough. In equation (17), VIN is the input voltage, FM is the PWM comparator gain (refer to equation (25)). Type III Compensation Determine the compensation at no load, the worst case condition. Assume the time constant of the resistor and capacitor across the output inductors matches that of the inductor, the crossover frequency of the voltage loop can be estimated by Equations (19).
fC
R DRP 2S * C E GCS * R FB R LE
(19)
Choose the desired crossover frequency fc1 around fc estimated by Equation (19). Select other components to ensure the slope of close loop gain is -20dB/Dec around the crossover frequency. Choose resistor RFB1 according to Equation (20), and determine CFB and CDRP from Equations (21) and (22).
R FB1
1 R FB 2
to
R FB1
2 R FB 3
(20)
C FB
4S f C1 R FB1
( R FB R FB1 ) C FB R DRP
1
(21)
C DRP
(22)
RCOMP and CCOMP have limited effect on the crossover frequency, and are used only to fine tune the crossover frequency and transient load response. Determine RCOMP and CCOMP from Equations (23) and (24), where FM is the PWM comparator gain defined by Equation (25).
RCOMP
(2S f C1 ) 2 LE C E R FB V I FM
10 LE C E RCOMP
VO V I * V RAMP
(23)
C COMP
(24)
FM
(25)
CCP1 is optional and may be needed in some applications to reduce the jitter caused by the high frequency noise. A ceramic capacitor between 10pF and 220pF is usually enough. Page 27 of 39 07/15/04
IR3093
DESIGN EXAMPLE
IR3093 Demo Board for VRD10.1 Application Specifications: Input Voltage: VI=12 V DAC Voltage: VDAC=1.35 V No Load Output Voltage Offset: VO_NLOFST=20 mV Output Current: IO=101 A DC Output Current Limit set point: ILIMIT=130 A Output Impedance: RO=1m VCC Ready to VCC Power Good Delay: tVccPG=0-10mS Soft Start Time: tSS=2 mS Dynamic VID Down-Slope Slew Rate: SRDOWN=2.5mV/uS Power Stage Design Control IC: IR3093 Phase Number: n=3 Switching Frequency: fSW=300 kHz Output Inductors: L=0.25 uH, RL=0.65 m Output Capacitors: C=0.007F, RCE=0.7 m External Components of IR3093 Oscillator Resistor Rosc Once the switching frequency is chosen, ROSC can be determined from the curve in the datasheet of IR3093 data sheet. For switching frequency of 300 kHz per phase, Choose ROSC=30k Soft Start Capacitor CSS Calculate the soft start capacitor from the required soft start time 2mS.
With the selected Css value, we can calculate the following delay times: The Over-Current fault latch delay time tOCDEL will be:
The soft start delay time is
Page 28 of 39
t SSDEL
C SS * 'V I CHG
0.1 * 10 6 * 1.1 1.8mS 60 * 10 6
t OCDEL
C SS * 'V I DISCHG
0.1 * 10 6 * 0.25 61 * 10 6
0.4mS
C SS
I CHG * t SS VO
60 * 10 6 * 2 * 10 1.35 20 * 10 3
3
0.09 * 10 6 F
Choose CSS = 0.1 uF
07/15/04
IR3093
The power good delay time is
VDAC Slew Rate Programming Capacitor CDAC and Resistor RDAC From IR3093 data sheet, the sink current ISINK of VDAC pin corresponding to ROSC=30k LV X$ Calculate the VDAC down-slope slew-rate programming capacitor from the required down-slope slew rate.
Choose CVDAC = 33nF Calculate the programming resistor.
In practice slightly adjust RDAC to get desired slew rate. Over Current Setting Resistor ROCSET According to the spec, the output current limit set point ILIMIT = 130A. The bias current IOCSET set by RROSC is around 40uA. Assume the maximum temperature TL_MAX = 120 C, the room temperature TROOM=25 C, so

RL _ MAX
0.65 *10 3 [1 3850 *10 6 (120 25)] 0.9m:
Assume maximum IC temperature TIC_MAX=110C, the minimum current sense amplifier gain can be calculated from Equation (11).
GCS _ MIN
23.5 [1 1400 *10 6 (110 25)] 21
1.33 (12 1.33) 0.25 10 6 12 300 10 3
Using Equation (12) and (13) to calculate ROCSET:
'I
Vo (Vin Vo) L Vin fsw
[(
Choose ROCSET = 25 k No Load Output Voltage Setting Resistor RFB and Adaptive Voltage Positioning Resistor RDRP The value of the internal current source current IFB in the curve is 42uA according to RROSC = 30k Page 29 of 39 07/15/04
ROCSET
I LIMIT 'I ) RL _ MAX ] GCS _ MIN / I OCSET 3 2
RDAC
0.5
3.2 10 15 2 C DAC
0.5
33 *10
3.2 *10
(c)
(c)
CVDAC
(c)
I SINK SRDOWN
85 10 6 2.5 10 3 / 10
6
34nF
tVccPG
C SS * 'V I CHG
0.1 * 10 6 * (3.75 1.33 1.1) 60 * 10 6
2.2mS
15
92
3.4
15.8 A
130 15.8 [( ) 0.9 10 3 ] 21/(40 10 6 ) 3 2 24.2k:
IR3093
RFB
Choose RDRP = 3.09k
Inductor Current Sensing Capacitor CCS and Resistors RCS1 and RCS2 Choose capacitor CCS = 0.22uF calculate RCS1
Set BIASOUT voltage Resistor Rset Bias current ISETBIAS is around 160uA in this case. Set VBIASOUT around 8V to be gate drive voltage of MOSFETs.
Choose RSET=51.1k Compensation of Voltage Loop AL-Polymer output capacitors are used in the design, and the crossover frequency of the voltage loop can be estimated as,
RCOMP and CCOMP are used to fine tune the crossover frequency and transient load response. Choose the desired crossover frequency fc1 (=30kHz) and determine RCOMP and CCOMP.
FM
RCOMP
VO V I V RAMP
(2S f C1 ) 2 LE C E RFB VI FM
1.33 12 0.63
0.18
(2S 30 10 3 ) 2 (250 10 9 / 3) 0.007 499 5k: 12 0.18
!
C COMP
10 LE C E RCOMP
10 (250 10 9 / 3) 0.007 5 10 3
48nF
In practice, adjust RCOMP and CCOMP if need to get desired dynamic load response performance.
Page 30 of 39
07/15/04
fC
RDRP 2S C E (GCS RFB RLE RCE )
RSET
VBIASOUT 0.3 I SETBIAS
8 0.3 160 10 6
RCS 1
51.9k:
L RL CCS
0.25 *10 6 / 0.65 *10 0.22 *10 6
3
1.8k:
3.09 *103 28kHz 2S 0.007 [23.5 499 (0.65 *10 3 / 3) 0.7 *10 3 ]
RDRP
n RO
RFB RL _ MAX GCS _ MIN
IFB
VO _ NLOFST
20 * 10 42 *10
3 6
476
&KRRVH 5FB = 499
499 0.9 10 3 21 3.1k: 3 1 10 3
Choose RCS1=2k
IR3093
MathCAD file to estimate the power dissipation of the IC
this Mathcad file step by step shows how to estimate the power dissipation of IR3093 . Initial Conditions: No.of Phases: IC Supply Voltage:
n 3
Vcc 12 ( V)
, IC Supply Current(quiescent):
Iql 5 n
Total High side Driver VCCH supply current(quiescent): Total Low side Driver VCCL supply Current(quiescent): Biasout Voltage:
Vbias 7.5
Iqh 5 n ( mA) ( mA)
Icq 38 ( mA)
Switching Frequency per phase: Thermal Impedance of IC:
fsw 300 T JA 27 (oC/W)
( V)
( kHz)
The data from the selected MOSFETs: ControI FET IR6623, Number of Control FET per phase: Control FET total gate charge: Sync FET total gate charge: Power Dissipation:
Qgc 16 ( nC)
nc 1 ns 1
Synchronous FET IR6620, Number of sync. FET per phase:
Qgs 45 ( nC)
The IC will have less power dissipation if using external gate driver supply. For the worst case estimation, assuming using the bias regulator for all the gate drive supply voltage. 1. Quiescent Power dissipation Total Quiescent Power Dissipation:
Pq ( Icq Iqh Iql) Vcc 10
"
3
Pq
0.816 ( W )
2. The Power Loss to drive the gate of the MOSFETs With the assumption of the low MOSFET gate resistances, most gate drive losses are dissipated in the driver circuit.
Pdrv Vbias fsw 10 n ( nc Qgc ns Qgs ) 10
$ #
3
9
Where the
Ig fsw 10 n ( nc Qgc ns Qgs ) 10
3
1/4
Pdrv
0.412 ( W )
9
term in the equation gives the total
average bias current required to drive all the MOSFETs. 3. The bias regulator Power Loss to supply driving the MOSFETs
Preg ( Vcc Vbias) Ig Pdiss Preg 0.247 (W)
4. Total Power Dissipation of the IC:
Pq Pdrv Preg
And the total Junction temperature rising is:
Pdiss T JA
Pdiss
1.475 ( W ) 39.82 (oC)
Page 31 of 39
07/15/04
VID2 VID1 VID0 VID5 5VREF OVPSNS ENABLE OVP CSINP1 CSINM1
IR3093
48LD MLPQ
VCCH1
NC
IRU3092
LGND SETBIAS VCC CSINP3 CSINM3 BIASOUT PWRGD CSINP2 CSINM2 VID_SEL VCCL3 GATEL3
APPLICATION CIRCUIT - 3 PHASE OPTERON CONVERTER
Page 32 of 39
12VIN 1 2 12VIN VID3 VID4 ROSC VOSNSOCSET VDAC VDRP FB EAOUT SS/DEL SCOMP2 SCOMP3 1 2 GATEH1 PGND1 GATEL1 VCCL1_2 5VUVL GATEL2 PGND2 GATEH2 VCCH2 VCCH3 GATEH3 PGND3 VCORE 12VIN VRETURN 1 2 12VIN POWERGOOD
OVP ENABLE
Figure 12. 12V Control, 12V Power Opteron Converter
VID5 VID0 VID1 VID2 VID3 VID4
07/15/04
IR3093
VID2 VID1 VID0 VID5 5VREF OVPSNS ENABLE OVP CSINP1 CSINM1
IR3093
48LD MLPQ
VCCH1
NC
IRU3092
LGND SETBIAS VCC CSINP3 CSINM3 BIASOUT PWRGD CSINP2 CSINM2 VID_SEL VCCL3 GATEL3
APPLICATION CIRCUIT - 3 PHASE VR10.X CONVERTER
Page 33 of 39
5VIN 12VIN U6 1 2 5VIN VID3 VID4 ROSC VOSNSOCSET VDAC VDRP FB EAOUT SS/DEL SCOMP2 SCOMP3 1 2 GATEH1 PGND1 GATEL1 VCCL1_2 5VUVL GATEL2 PGND2 GATEH2 VCCH2 VCCH3 GATEH3 PGND3 VCORE 5VIN 5VIN VRETURN 1 2 12VIN
OVP ENABLE
VID5 VID0 VID1 VID2 VID3 VID4
Figure 13. 12V Control, 5V Power, VR10 Converter
POWERGOOD
07/15/04
IR3093
IR3093
LAYOUT GUIDELINES
The following layout guidelines are recommended to reduce the parasitic inductance and resistance of the PCB layout, therefore minimizing the noise coupled to the IC. Refer to the schematic in Figure 6 - System Diagram. x Dedicate at least one inner layer of the PCB as power ground plane (PGND). x The center pad of IC must be connected to ground plane (PGND) using the recommended via pattern shown in "Package Dimensions". x The IC's PGND1, 2, 3 and LGND should connect to the center pad under IC. x The following components must be grounded directly to the LGND pin on the IC using a ground plane on the component side of PCB: CSS, RSC2, RSC3, RSET, CVCC and C5VREF. The LGND should only be connected to ground plan on the center pad under IC x Place the decoupling capacitors CVCC and CBIAS as close as possible to the VCC and VCCL1_2, VCCL3 pins. The ground side of CBIAS should not be connected to LGND and it should directly grounded through vias. x The following components should be placed as close as possible to the respective pins on the IC: RROSC, ROCSET, CDAC, RDAC, CSS, CSC2, RSC2, CSC3, RSC3, RSET. x Place current sense capacitors CCS1, 2, 3 and resistors RCS1, 2, 3 as close as possible to CSINP1, 2, 3 pins of IC and route the two current sense signals in pairs connecting to the IC. The current sense signals should be located away from gate drive signals and switch nodes. x Use Kelvin connections to route the current sense traces to each individual phase inductor, in order to achieve good current share between phases. x Place the input decoupling capacitors closer to the drain of top MOSFET and the source of the bottom MOSFET. If possible, Use multiple smaller value ceramic caps instead of one big cap, or use low inductance type of ceramic cap, to reduce the parasitic inductance. x Route the high current paths using wide and short traces or polygons. Use multiple vias for connections between layers. x The symmetry of the following connections from phase to phase is important for proper operation: The Kelvin connections of the current sense signals to inductors. The gate drive signals from the IC to the MOSFETS. The polygon shape of switching nodes.
Page 34 of 39
07/15/04
IR3093
PCB AND STENCIL DESIGN METHODOLOGY
x x x 7x7 48 Lead 0.5mm pitch MLPQ
See Figures 14-16. PCB Metal Design (0.5mm Pitch Leads) 1. Lead land width should be equal to nominal part lead width. The minimum lead to lead spacing should be PP WR PLQLPL]H VKRUWLQJ 2. Lead land length should be equal to maximum part lead length + 0.2 mm outboard extension + 0.05mm inboard extension. The outboard extension ensures a large and inspectable toe fillet, and the inboard extension will accommodate any part misalignment and ensure a fillet. 3. Center pad land length and width should be = maximum part pad length and width. However, the minimum metal to metal spacing should be PP R] &RSSHU PP IRU R] Copper and PP IRU R] &RSSHU 4. Sixteen 0.30mm diameter vias shall be placed in the pad land spaced at 1.2mm, and connected to ground to minimize the noise effect on the IC, and to transfer heat to the PCB. PCB Solder Resist Design (0.5mm Pitch Leads) 1. Lead lands. The solder resist should be pulled away from the metal lead lands by a minimum of 0.060mm. The solder resist mis-alignment is a maximum of 0.050mm and it is recommended that the lead lands are all NSMD. Therefore pulling the S/R 0.060mm will always ensure NSMD pads. 2. The minimum solder resist width is 0.13mm, therefore it is recommended that the solder resist is completely removed from between the lead lands forming a single opening for each "group" of lead lands. 3. At the inside corner of the solder resist where the lead land groups meet, it is recommended to provide a fillet so a solder resist width of PP UHPDLQV 4. Land Pad. The land pad should be SMD, with a minimum overlap of the solder resist onto the copper of 0.060mm to accommodate solder resist mis-alignment. In 0.5mm pitch cases it is allowable to have the solder resist opening for the land pad to be smaller than the part pad. 5. Ensure that the solder resist in-between the lead lands and the pad land is PP GXH WR the high aspect ratio of the solder resist strip separating the lead lands from the pad land. 6. The single via in the land pad should be tented with solder resist 0.4mm diameter, or 0.1mm larger than the diameter of the via. Stencil Design (0.5mm Pitch Leads) 1. The stencil apertures for the lead lands should be approximately 80% of the area of the lead lands. Reducing the amount of solder deposited will minimize the occurrence of lead shorts. Since for 0.5mm pitch devices the leads are only 0.25mm wide, the stencil apertures should not be made narrower; openings in stencils < 0.25mm wide are difficult to maintain repeatable solder release. 2. The stencil lead land apertures should therefore be shortened in length by 80% and centered on the lead land. 3. The center land pad aperture should be striped with 0.25mm wide openings and spaces to deposit approximately 50% area of solder on the center pad. If too much solder is deposited on the center land pad the part will float and the lead lands will be open. 4. The maximum length and width of the center land pad stencil aperture should be equal to the solder resist opening minus an annular 0.2mm pull back to decrease the incidence of shorting the center land to the lead lands when the part is pushed into the solder paste.
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IR3093
Figure 14. PCB metal and solder resist.
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IR3093
Figure 15. PCB metal and component placement.
Page 37 of 39
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IR3093
Figure 16. Stencil design.
Page 38 of 39
07/15/04
IR3093
PACKAGE DIMENSIONS
Data and specifications subject to change without notice. This product has been designed and qualified for the Consumer market. Qualification Standards can be found on IR's Web site.
IR WORLD HEADQUARTERS: 233 Kansas St., El Segundo, California 90245, USA Tel: (310) 252-7105 TAC Fax: (310) 252-7903 Visit us at www.irf.com for sales contact information
www.irf.com
Page 39 of 39 07/15/04

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