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High Performance Secondary Side Controller with Synchronous Rectifier
POWER MANAGEMENT Description
The SC4910A/B is an integrated, full featured, secondary side controller designed for use in single ended and isolated switch mode power supplies with synchronous rectification where efficiency and fast transient response are of primary concern. The SC4910A/B has outputs for both primary FET and secondary synchronous rectification. The primary drive output is designed to drive a small and low cost pulse transformer to isolate the primary FET driver. The secondary control makes it much easier to monitor and control the system load with tight control loops and implement load current sharing and synchronous rectification. The SC4910A/B features synchronous rectification, multiphase link capability, programmable secondary side delay, programmable switching frequency and programmable maximum duty cycle. It is designed for either current mode or voltage mode operation. The SC4910A has a typical turn-on threshold of 9V and the SC4910B has a threshold of 4.5V.
SC4910A/B
Features
Synchronous rectification with adaptive control Programmable secondary side delay Programmable switching frequency Programmable max. duty cycle Remote voltage sense capability Close-loop soft start with active low shutdown 0.75V precision reference for low output applications Oscillator sychronization Undervoltage Lockout Operation to 1MHz Current-mode or voltage-mode operation Single stage power conversion with multiphase link capability (with SC4201) Monotonic start-up with pre-biased output Active current sharing capability 20 pin TSSOP package
Applications
Telecom isolated DC to DC converters Isolated VRMS Networking power supplies Industrial power supplies Distributed power architectures High density power modules
L1 R1 C2 LOAD
Typical Application Circuit
+Vin T1 R2 C1 M1 D1 M2
C3
SC1301 SC1301
+12V SC1301 M3 12 T2 D2 4 R3 R4 R5 10 20 19 3 15 5 PVCC CS OUTA RT1 RT2 SS DELAY VREF AGND C9 C8 T3 C10 7 R9 PGND 8 13 PVCC 14 AVCC 16 ISHARE PHASE OUTB COMP FB SYNC/EN -SENSE PGND 9 6 11 17 18 2 1 R8 C6 C5 R6 R7 C4 SC4910
D3
Revision: June 1, 2005
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SC4910A/B
POWER MANAGEMENT Absolute Maximum Ratings
Exceeding the specifications below may result in permanent damage to the device, or device malfunction. Operation outside of the parameters specified in the Electrical Characteristics section is not implied. Exposure to Absolute Maximum rated conditions for extended periods of time may affect device reliability.
Parameter Supply Voltage Output Voltage Phase FB, COMP, SYNC/EN, ISHARE OUTA & OUTB Current Source or Sink Junction Temperature Range Storage Temperature Range Lead Temperature (Soldering) 10 Sec.
Symbol V cc
Maximum 18 V cc V cc -0.3 to 7 150
Units V V V V mA C C C
TJ TSTG TLEAD
= 50K, C = 0.1F.
-40 to +150 -60 to +150 260
Electrical Characteristics
Unless specified: TA = T = -40C to 125C , VCC = 12V, R = R = 50K, R
J T1 T2 DELAY SS
Parameter Pow er Supply Operating Current Undervoltage Lockout Start Threshold
Test Conditions
Min
Typ
Max
Unit
SYNC/EN = Low
10
15
mA
S C 4910A S C 4910B S C 4910A S C 4910B
8.7 4.35 400 200
9.0 4.50 550 300
9.3 4.75 700 375
V V mV mV
UVLO Hysteresis VREF Reference Output Voltage Line Regulation Load Regulation Soft Start SS Output Voltage Accuracy Line Regulation Impedance
(2)
S C 4910A S C 4910B 9.3V < Vcc < 15V 0mA < IREF < 5mA
4.75 2.97
5.0 3.30 15 2
5.25 3.63 30 10
V V mV mV
0.75 TA = TJ = 25C -1 -1.5 9.3V < Vcc < 15V -5 0 7K
2
V +1 +1.5 +5 % mV
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SC4910A/B
POWER MANAGEMENT Electrical Characteristics (Cont.)
Unless specified: TA = T = -40C to 125C , VCC = 12V, R = R = 50K, R
J T1 T2 DELAY
= 50K, C
SS
= 0.1F.
Parameter Error Amplifier Input Bias Current Offset Voltage Open Loop Gain CMRR PSRR
(1) (1)
Test Conditions
Min
Typ
Max
Unit
0.1 2 80 70 70 ICOMP = 1.0mA ICOMP = 1.0mA 5.0 2.0 1.75 1.9 0.9
5 7
A mV dB dB dB V
Output High Voltage Output Low Voltage Unity Gain Bandwidth (1) Slew Rate (1) Oscillator Frequency Range
1.0
V MHz V/S
Min. Frequency RT1 = RT2 = 500K Max. Frequency RT1 = RT2 = 25K
50 1000 450 500 2.5 1.0 2.0 0.8 550
KHz
Frequency Peak Voltage Valley Voltage
(1) (1)
KHz V V V V
Enable Input High Enable Input Low Duty Cycle Maximum Duty Cycle Minimum Duty Cycle Duty Cycle Tolerance Current Limit Cycle by Cycle Threshold Shutdown Threshold Delay to Output (2) Input Impedance
(2) (2)
90 0 -5 +5
% % %
0.975 1.1
1.025 1.25 100 20
1.075 1.4
V V nS k
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SC4910A/B
POWER MANAGEMENT Electrical Characteristics (Cont.)
Unless specified: TA = T = -40C to 125C , VCC = 12V, R = R = 50K, R
J T1 T2 DELAY
= 50K, C
SS
= 0.1F.
Parameter OUTA and OUTB Output Low Output High Rise Time
(2)
Test Conditions
Min
Typ
Max
Unit
IOUTPUT = 100mA IOUTPUT = 100mA COUT = 100pF COUT = 100pF
(2) (2)
1 9.75 10 20 20
1.3
V V nS nS
Fall Time (2) Delay OUTB Falling to OUTA Rising OUTA Falling to OUTB Rising
RDELAY = 50K PHASE > 1.5V PHASE < 1.5V
70 220 30
nS nS
Current Share Error Amplifier Transconductance
(1)
0.18 10
mS A
Output Source or Sink Current (1)
Notes: (1) Guaranteed by design. (2) Guaranteed by characterization. (3) This device is ESD sensitive. Use of standard ESD handling requirements are required.
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SC4910A/B
POWER MANAGEMENT Pin Configurations
TOP VIEW
-SENSE SYNC/EN SS CS VREF PHASE AGND PGND PGND OUTA 1 2 3 4 5 6 7 8 9 10 20 19 18 17 16 15 14 13 12 11 RT1 RT2 FB COMP ISHARE DELAY AVCC PVCC PVCC OUTB
Ordering Information
Part Number SC4910AITSTRT(2) SC4910BITSTRT(2) P ackag e TSSOP-20(1)
Notes: (1) Only available in tape and reel packaging. A reel contains 2500 devices. (2) Lead free product. This product is fully WEEE and RoHS compliant.
(20 Pin TSSOP)
Marking Information
Part Number (Example: 1471) yyww = Date Code (Example: 0012) xxxxx = Semtech Lot No. (Example: P94A01)
Part Number (Example: 1471) yyww = Date Code (Example: 0012) xxxxx = Semtech Lot No. (Example: P94A01)
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SC4910A/B
POWER MANAGEMENT Pin Descriptions
Pin # 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Pin Name -SENSE SYNC/EN SS CS VREF PHASE AGND PGND PGND OUTA OUTB PVC C PVC C AVCC DELAY Remote voltage sense return. Bidirectional synchronization and enable /disable pin. Referenced to -SENSE. Soft start. Current sense input. 5V internal reference output. Phase node for synchronous rectification. Analog ground. Power ground for OUTA. Power ground for OUTB. Output driver for primary MOSFET and secondary forward MOSFET. Low during UVLO. Output the MOSFET driving signal for forward rectifier. Low during UVLO. Power supply for OUTB. Power supply for OUTA. Analog supply voltage. Predictive delay between OUTA and OUTB. The delay is from turn-off of the freewheeling MOSFET to turn-on of the forward MOSFET and primary MOSFET. The delay time is 20 to 200nS programmable. Current share bus. Feedback compensation. F e e d b a ck. Connect to timing resistor RT2 to control the negative ramp of the internal oscillator. Connect to timing resistor RT1 to control the positive ramp of the internal oscillator. Pin Function
16 17 18 19 20
ISHARE COMP FB RT2 RT1
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SC4910A/B
POWER MANAGEMENT Block Diagram
Figure. 1
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SC4910A/B
POWER MANAGEMENT Applications Information
The SC4910A/B is a secondary side PWM controller working either in current mode or voltage mode mainly for applications of forward converters with synchronous rectification. While the OUTA drives the primary MOSFET through transformer and the secondary forward rectifier, the OUTB drives the secondary freewheeling rectifier. The switching frequency and maximum duty cycle can be programmable with two resistors. The delay time from the falling edge of OUTA to the rising edge of OUTB is adaptive by monitoring the phase node voltage. The delay time from the falling edge of OUTB to the rising edge of OUTA is determined by a programming resistor from the DELAY pin to ground. The ISHARE pin allows for current sharing among the parallel operating units to make current equally distribute load. The -SENSE pin separated from GND pin provides true output voltage remote sense capability. Other features include soft start, sychronization or enable/disable by user, provided 5V reference voltage. Oscillator The frequency and duty cycle of the oscillator is controlled by placing two resistors from the RT1 and RT2 pins to ground. The resistor at RT1 controls the maximum "on" duty cycle and the resistor at RT2 controls the "off" portion of a cycle. When the resistor at RT1 is equal to that at RT2, the maximum duty cycle will be approximately 50%. The following formula is used to determine the time duration of the "on" and "off" portions: SYNC/EN The enable function looks at the SYNC/EN pin and an internal timing capacitor. If the SYNC/EN pin is low and the internal timing capacitor voltage is high, then the SC4910 is disabled with OUTA, OUTB and SS pulled low. When the SYNC/EN pin is held high, the device is enabled and runs off of the internal oscillator. When a rising signal is detected on the SYNC/EN pin a one-shot is triggered and discharges the internal timing capacitor. As long as the internal timing capacitor is below an internal reference level, the device will synchronize with the external pulse. If the internal timing capacitor is allowed to charge up to the internal reference level before another SYNC pulse is detected, the device will switch back to the internal oscillator. Soft Start The SS pin is connected to the internal reference, 0.75V, through an internal 6K ohm resistor. The SS pin is also connected to the non-inverting input of the error amplifier. With an external capacitor connected to this pin, the soft start timing will be determined by this RC time constant. During start-up, the SS pin is held low until the undervoltage lockout threshold is reached. Once the UVLO threshold is reach, the SS pin is released and the device will regulate to the voltage on this pin. Undervoltage Lockout When the supply voltage VCC is below the undervoltage lockout threshold, both OUTA and OUTB are held low. The SS pin and the COMP pin are also held low. Once the undervoltage lockout threshold has been surpassed, OUTA, OUTB, SS and COMP are released for normal operation.
t = RT x 20 x 10
-12
Current Sense and Current Limit The CS pin has an input impedance of 20K ohms and swings from 1.0V to 2.5V. With a 5K ohm resistor from CS to ground, the device operates in voltage mode with a ramp that will swing from 0.2V to 0.5V. When the 5K resistor is connect to a voltage that is proportional to the primary side current, the device will operate in current mode. The cycle-by-cycle current limit is triggered when the CS pin voltage rises above 1V. If CS exceeds 1.25V, the faulty latch will be set and the outputs will be driven low. The soft start capacitor is then discharged by the internal current sink. No outputs are allowed until the soft start capacitor is fully discharged to 0.15V. At this point the fault latch will be reset and the SC4910 will begin a soft start process. This results in a hiccup current limit mode for continuous fault conditions.
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SC4910A/B
POWER MANAGEMENT Applications Information (Cont.)
Programmable Delay SC4910 is for single ended topologies with secondary side synchronous rectification. It provides outputs to drive the primary MOSFET through a small pulse transformer and the secondary synchronous rectifiers directly. To avoid cross conduction and optimize performance, adjustable delay is necessary between forwarding and freewheeling switches. The delay from falling edge of OUTB to rising edge of OUTA is determined by a resistor from the DELAY pin to ground. The following formula is used to calculate the delay time:
t DELAY = R * 1 - 12 + 20nS
where n - Power transformer primary to secondary turns ratio NS - Secondary turns of current sense transformer Io(pk) - Peak inductor current An example of choosing a current sense resistor is given below. Assume the converter full load current is 20A and peak inductor current is 23A, the power transformer primary to secondary turns ratio is 6:1 and the current sense transformer primary to secondary turns ratio is 1:100, then,
Rs = 1.0 * 6 * 100 21 120% * 23
where, R is the delay time setting resistor. R should be between 20K and 200K. The delay time from falling edge of OUTA to rising edge of OUTB is adaptive and is triggered when the PHASE node falls below 1.5V. If after 220nS the PHASE node has still not fallen, the device will automatically switch. Operation Mode SC4910 could be configured either current mode or voltage mode operation. In current mode, the current sense signal comes to the CS pin while an external resistor could configure slope compensation. In voltage mode, an external resistor forms sawtooth with the internal 20K resistor for voltage mode operation while current limit signal comes to the same pin. In current mode, which is preferred for application of SC4910, current is sensed by a current transformer for current feedback and over current protection. The current in the primary switch is sensed and controlled by developing a voltage proportional to current across a sense resistor on the secondary. The sensed voltage is then fed into the CS pin of SC4910. The typical current limit threshold in the current sense pin of the SC4910 is 1.0V. The over current limit is assumed typical 120% of full load current. Then the current sense resistor can be calculated by the following equation:
Rs = 1.0 * n * NS 120 % * IO (pk )
Slope Compensation Slope compensation is needed to prevent sub-harmonic oscillation at duty cycle higher than 50% and to compensate the peak to average difference in peak current mode control. The following equation can be used to calculate the external slope. If negative Se is obtained by the equation, no slope compensation is needed.
Se 2VOn - VIN VIN * IL RS * * 2( VIN - VOn) VOn n * NS
where Se - External slope magnitude Vin - Low input line voltage Vo - Output voltage n - Power transformer primary to secondary turns ratio NS - Secondary turns of current sense transformer IL - Peak-to-peak Inductor current ripple For example, if the low input line voltage is 36V, output voltage is 3.3V, power transformer primary to secondary turns ratio is 6:1; the peak-to-peak inductor current ripple is 6A, and current sense gain RS is 21W, then the external slope needed is:
Se 2 * 3.3 * 6 - 36 36 * 6 21 * * 85mV 2(36 - 3.3 * 6) 3.3 * 6 6 * 100
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SC4910A/B
POWER MANAGEMENT Applications Information (Cont.)
This is the minimum external slope required to avoid subharmonic oscillation at low input line. With SC4910, the external slope is very easy to implement. Referring to Figure 2, R12 is the current sense resistor. R10 and the internal 20K resistor divide the internal slope 1.0V - 2.5V down to the required compensation slope.
VIN * R S ) * 20 (Se - L M * NS * fS R10 = VIN * R S (2.5 - 1.0) - (Se - ) L M * NS * f S
Closed-Loop Compensation The simplified control-to-output transfer function for the forward converter with current mode control, for small value of external slope ( Se Sn, Sn is on-time slope of sensed current waveform) is given by:
s z = G vgo s 1+ p 1+
G vg
where: LM - Power transformer magnetizing inductance fS = Switching frequency In the example,
36 * 21 ) * 20 450E - 6 * 100 * 250E3 R10 = = 240 36 * 21 (2.5 - 1.0) - (0.085 - ) 450E - 6 * 100 * 250E3 (0.085 -
where
G vgo = nNS VO DC gain of power stage with current loop closed IOR S
P =
1 Do min ant pole of power stage with current loop closed RC
Z =
1 ESR zero of power stage R ESR C
R10 14 13 R12 C13 4 10 R21 20 19 R22 3 15 5 CS OUTA RT1 RT2 SS DELAY PGND AGND PGND VREF U5 SC4910 12
where R - Load resistance C - Output capacitance RESR - Output capacitors ESR
ISHARE 16 2 6 11 17 18 1
SY NC/EN PHASE OUTB COMP FB -SENSE
For the given example above, at low line and R = 0.165, C = 2 x 680uF = 1360uF, RESR = 17m, therefore:
G vgo = 6 * 100 * 3.3 = 4.71 = 13dB 20 * 21
AVCC
PVCC
PVCC
C22
R25
C36
1 = 4456 rad / s = 710Hz 0.165 X 1360E - 6 1 Z = = 43253 rad / s = 6887Hz 17E - 3 X 1360E - 6 P =
7
8
Figure 2
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SC4910A/B
POWER MANAGEMENT Applications Information (Cont.)
Type 2 compensator (Figure 3) is needed for the above current mode control. The compensation network gives the following characteristics:
C3
GCOMP
V ref
Figure 3 where
1 = 1 R 1 ( C1 + C 3 ) 1 R 2 C1 1 CC R2 1 3 C1 + C 3
ZC = PC =
The loop gain will be given by:
s s 1+ ZC Vref z 1 = G vgo * * s s s VO 1+ 1+ p PC 1+
T = G vg GCOMPK FB
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s z =1 s s 1+ p 1+
R2 R1
C1
The goal of the compensation design is to shape the loop with high DC gain, high bandwidth, enough phase margin, and high attenuation for high frequency noises. Figure 4 gives the asymptotic diagrams of the power stage with current loop closed and its loop gain. One integrator is added to increase the DC gain. Wzc is used to cancel the power stage pole wp so that the loop gain has -20dB rate when it reaches 0 dB line. wpc is placed at output capacitor ESR or half switching frequency, whichever is lower. Arbitrarily choose R2, then
C1 =
1
+
R 2P
, C3 =
C1 1 ,R1 = PC I (C1 + C3 ) -1 ZC
I is adjusted for satisfactory phase margin and crossover frequency. Synchronization Synchronization of oscillators in multiphase operation allows for reduced size of filtering components and improved dynamic response. SC4910 provides single stage conversion where SC4201 provides the multiphase function. SC4910 and SC4201 are placed on the secondary side, outputs A and C of the SC4201 are fed into the Sync pins of 2 separate SC4910's. Both power supplies operate 180 degrees apart. SC4201 can be configured up to 4 phase operation.
Loop gain T(s)
zc
Compensator Power stage pc
fs P C Z
Figure 4
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SC4910A/B
POWER MANAGEMENT Applications Information (Cont.)
Load Remote Sensing Dedicated -SENSE pin provides true remote sensing of the regulated supply's output terminal voltage for high current applications. As shown in Figure 5, the bandgap reference "ground " is brought out as -Sense, which is connected to the "load ground" and to the local analog ground by the resistor R10. With this way combined with upper side R1, the voltage drop on power line is offset and the load voltage is truly sensed. Load Current Sharing A single wire connected between the ISHARE pins will force current sharing between parallel units for paralleling or n+1 redundant operation. The ISHARE pin allows for current sharing between several parallel units. The ISHARE pin connects internally to the non-inverting input of ISHARE amplifier. An internal 4K resistor is between the inverting and non-inverting inputs of this amplifier, with the inverting input also connected to the COMP pin. The output of the amplifier connects to the SS (0.75V ref) pin. During normal operation, when all devices are sharing the load current equally, the COMP pin voltages on each units should be approximately equal. If one of the devices begins to take on too much or too little of the load, the difference in COMP pin voltage will cause the ISHARE amplifier to adjust the SS (0.75V ref) voltage accordingly. In the event of ISHARE pulled down below 1V, the ISHARE amplifier is disabled to prevent output voltage of the unit lower than specification.
R1 LOAD
12
13
PVCC
PVCC
4 10 20 19 3 15 5
AVCC
14
SC4910
CS OUTA RT1 RT2 SS DELAY VREF AGND PGND
ISHARE PHASE OUTB COMP FB SY NC/EN -SENSE PGND
16 6 11 17 18 2 1 R10 R8 C6 C5 R7 R6
7
8
9
Figure 5
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SC4910A/B
POWER MANAGEMENT Typical Characteristics
Icc vs Vcc
25.00 18.00 16.00 Icc (mA) 14.00 12.00 10.00 8.00 4.5 6.5 8.5 10.5 Vcc (V) 12.5 14.5
Sync/En = Low TA = 25C Vcc = 12V
Icc vs Temperature
20.00
Sync/En = High Syn/En = High
Icc (mA)
15.00 10.00 5.00 0.00 -40 -20 0 20 40 60 80 100 120 Temperature (C)
Syn/En = Low
(Sc4910A) UVLO Hysteresis vs Temperature
580.00 UVLO Hysteresis (mV) 575.00 570.00 565.00 560.00 555.00 550.00 -40 -20 0 20 40 60 80 100 120 Temperature (C) UVLO High Thre shold (V) 8.98 8.97 8.96 8.95 8.94 8.93 8.92 8.91 8.90
(Sc4910A) UVLO High Threshold vs Temperature
-40
-20
0
20
40
60
80
100
120
Temperature (C)
(Sc4910B) UVLO Hysteresis vs Temperature
302.00 298.00 296.00 294.00 292.00 290.00 288.00 286.00 284.00 -40 -20 0 20 40 60 80 100 120 Temperature (C) UVLO High Thre shold (V) UVLO Hyste resis (mV) 300.00 4.56 4.55 4.55 4.54 4.54 4.53 4.53 4.52 4.52
(Sc4910B) UVLO High Threshold vs Temperature
-40
-20
0
20
40
60
80
100
120
Temperature (C)
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SC4910A/B
POWER MANAGEMENT Typical Characteristics (Cont.)
Bandgap Voltage vs Vcc
0.755 Bandgap Voltage (V) 0.753 0.751 0.749 0.747 0.745 9 10 11 12 Vcc (V) 13 14 15
TA = 25C Iout = 0mA
Bandgap Voltage vs Temperature
0.7505
Vcc = 12V
Bandgap Voltage (V)
0.7500 0.7495 0.7490 0.7485 0.7480 0.7475 -40 -20 0 20 40 60 80 100 120 Temperature (C)
Error Amp Input Bias Current vs Vcc
Error Amp Input Bias Curre nt (nA) Error Amp Input Bias Curre nt (nA) 140.00 120.00 100.00 80.00 60.00 40.00 20.00 0.00 4.5 6.5 8.5 10.5 Vcc (V) 12.5 14.5
Vfb = 0V TA = 25C Vfb = 5V
Error Amp Input Bias Current vs Temperature
600.00 500.00 400.00 300.00 200.00 100.00 0.00 -100.00 -200.00 -40 -20 0 20 40 60 80 100 120 Temperature (C)
Vfb = 0V Vfb = 5V Vcc = 12V
Error Amp Offset Voltage vs Vcc
TA = 25C
Error Amp Offset Voltage vs Temperature
Error Amp Offset Voltage (mV) 1.50 1.40 1.30 1.20 1.10 1.00 0.90 0.80 -40 -20 0 20 40 60 80 100 120 Temperature (C)
1.40 1.20 1.00 0.80 0.60 0.40 0.20 0.00 -0.20 -0.40 -0.60 4.5
Error Amp Offset Voltage (mV)
Vcc = 12V
6.5
8.5
10.5 Vcc (V)
12.5
14.5
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SC4910A/B
POWER MANAGEMENT Typical Characteristics (Cont.)
Error Amp Output Voltage vs Temperature
Error Amp Output Voltage (V) 3.00 2.50 2.00 1.50 1.00
Low Vcc = 12V Icomp = 1mA
Oscillator Frequency vs Temperature
525 520 515 510 505 500 495 490 485 480 475
Rt1 = Rt2 = 50kohm
High
0.50 -40 -20 0 20 40 60 80 100 120 Temperature (C)
Oscillator Frequency (kHz)
-40
-20
0
20
40
60
80
100
120
Temperature (C)
Enable Voltage vs Temperature
3.00 Enable Voltage (V) 2.50 2.00 1.50 1.00 0.50 -40 -20 0 20 40 60 80 100 120 Temperature (C)
Low High Vcc = 12V
Max Duty Cycle vs Temperature
91.00 90.80 90.60 90.40 90.20 90.00 89.80 89.60 89.40 89.20 89.00 -40
Output A
Max Duty Cycle (%)
-20
0
20
40
60
80
100
120
Temperature (C)
Progammable Delay vs Temperature
90.00 Progammable De lay (nS)
Rdelay = 50kohm
85.00 80.00 75.00 70.00 65.00 60.00 -40 -20 0 20 40 60 80 100 120 Temperature (C)
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* : Optional 3.3V/20A CON2 1 Vout+ T1 8 7 6 5 5 R1 39K D1 1 2 3 4 1 2 3 4 ES1D R4 10K R6 10K D5 1N4148WS U2 SC1302A +12V C11 0.1uF 2 R38 10K 1 6 8 Q5 FMMT718 R5 4.7 7 Q2 FMMT718 R18 10K R3 5.1 3 Sense 2 8 M1 si4842dy 8 1 7 2 6 3 5 4 4 Sense D14 B130L C6 100uF C7 100uF C8 680uF C9 680uF D15 SMAZ20 R2 10.0 C2 0.1uF,100V C32 2.2nF C1 2.2nF R37 5.1 10 8 7 6 5 PA0168A M3 si4842dy L1 1.3uH M4 si4842dy
CON1
+Vin
5 6 7 8
5 6 7 8
5 6 7 8
3
1
4 3 2 1
4 3 2 1
4 3 2 1
R17 1K 10 2 C17 0.1uF R52 1K U3 SC4431 12 R53 14 13 0 +12V Q3 FMMT718 D3 1N4148WS 1 6 8 AVCC PVCC Q4 Not Populated f s=250KHz 7 R21 124K 20 RT1 RT2 SS DELAY AGND PGND PGND VREF 7 8 C36 0.1uF 9 R26 10.0 -SENSE 1 FB 18 1.0nF 43K COMP 17 C21 R23 R24 2.0K U5 SC4910 OUTB 11 PHASE 19 4 15 3 5 R22 75K 3 C20 100pF 6 U4 SC1302A R50 5 2 10 OUTA R19 6.8K SY NC/EN 2 D9 1N4148WS C18 0.1uF T3 C19 0.1uF 6 PE68386 1 4 3 10 D20* 1N5819HW PVCC C12 0.1uF 4 CS ISHARE 16 C51 10uF Ilim=24A C16 0.1uF
C22 0.1uF R25 62K
+12PRI T4 2 1 3 8 C26 0.47uF R29 68 C27 10uF 1 8 U6 SC4911 C29 150pF C28 100pF R30 100K R28 2.7MEG 4 PB2090 5 C23 47uF D11 1N4148WS +Vin R27 100K
D10 1N4148WS
D12 1N4148WS C24 47uF
+12V C25 47uF
R31 470K VCC
FB
LUVLO
3
OUT
7
Q1 Si2320DS
4 COMP RT R33 100K C37 470pF R35 20K C30 47nF
ILIM GND
5
R32 51 C31 1000pF R34 1.00
2
R36 100K
6
Vr f e
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8 7 6 5 M2si4842dy 1 2 3 4 5 Ishare D2 1N4148WS 7 T2 3 1 P8208T D21* 1N5819HW R13 10.0K C50 22nF 4 +12V 5 R14 37.4K C14 0.1uF D22* 1N5819HW +12V 4 7 VoutR8 4.7 5 8 M7 Not populated M6 si4490dy D6 1N4148WS R10 1.5K R12 22 R51 C13 150pF R15 18.2K R11 10K M5 si4490dy
Vin+
C3 1u,100V
C4 1u,100V
C5 1u,100V
C33 1u,100V
C34 1u,100V
Vin-
POWER MANAGEMENT Evaluation Board Schematics
6
EN
16
SC4910A/B
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SC4910A/B
POWER MANAGEMENT Evaluation Board Bill of Materials
Item 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 Quantity Reference 2 1 5 4 10 2 1 1 3 1 1 1 1 1 1 1 1 10 1 1 1 4 2 1 1 2 2 6 2 C1,C32 C2 C3,C4,C5,C33,C34 C6,C7,C8,C9 C11,C12,C14,C16,C17,C18,C19, C22,C36, C51 C13,C29 C 20 C 21 C23,C24,C25 C 26 C 27 C 28 C 30 C 31 C 37 C 50 D1 D2,D5,D6,D9, D10,D11,D12,D20,D21,D22 D 14 D 15 L1 M1,M2,M3,M4 M5,M6 Q1 R1 R2,R26 R3,R37 R4,R6,R11,R17,R18,R38 R5, R8
17
Part 2.2nF 0.1uF,100V 1uF,100V 680uF, 4V 0.1uF 150pF 560pF 1.5nF 47uF, 16V 0.47uF 10uF, 10V 100pF 47nF 1000pF 470pF 22nF E S 1D
Manufacturer #
Foot Print SM/C_0805
TDK, C3216X7R2A104M Murata, GRM55RR72A105KA01B Sanyo, 4TPB680
SM/C_1206 SM/C_2220 SM/CT_7343 SM/C_0805 SM/C_0805 SM/C_0805 SM/C_0805
Sanyo, 16TPB47
SM/CT_7343 SM/C_1206
Murata, GRM32ER61C106KC31L
SM/C_1210 SM/C_0805 SM/C_0805 SM/C_0805 SM/C_0805 SM/C_0805
Diodes Inc. ES1D-13
SM/_SMA SOD123 SMA SMA PCC-S1 SO-8 SO-8 SM/SOT23_123 SM/R_0805 SM/R_0805 SM/R_0805 SM/R_0805 SM/R_0805
www.semtech.com
1N5819HW Diodes Inc. 1N5819HW-7 B 130L SMAJ20A 1.3uH si 4 8 4 2 d y si 4 4 9 0 d y S i 2320D S 39K 10 5.1 10K 4.7 Diodes Inc. B130L-13 Diodes Inc. SMAJ120A-13 Panasonic, ETQPAF1R3E Vishay Vishay Vishay
2005 Semtech Corp.
SC4910A/B
POWER MANAGEMENT Evaluation Board Bill of Materials
Item 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 Quantity Reference 1 1 1 1 1 1 1 1 1 1 1 3 1 3 1 1 1 1 1 2 1 1 1 1 1 2 1 1 1 R10 R12 R13 R14 R15 R19 R21 R22 R23 R24 R25 R27,R30,R33 R28 R29 R31 R32 R34 R35 R36 R50,R51 R52 T1 T2 T3 T4 U2, U4 U3 U5 U6 Part 412 22 10.0K 37.4K 18.2K 21.5K 160K 40.2K 43K 6.19K 110K 100K 2.7MEG 68 383K 51 1 4.7K 130K 10 1.0K PA0168 P 8208T P E 68386 31414R S C 1302A S C 4431 S C 4910 SC4911 Pulse Pulse Pulse Midcom Semtech Semtech Semtech Semtech SOT23_5PIN SOT23_5PIN TSSOP-20 MSOP-8 Manufacturer # Foot Print SM/R_0805 SM/R_0805 SM/R_0805 SM/R_0805 SM/R_0805 SM/R_0805 SM/R_0805 SM/R_0805 SM/R_0805 SM/R_0805 SM/R_0805 SM/R_0805 SM/R_0805 SM/R_0805 SM/R_0805 SM/R_0805 SM/R_0805 SM/R_0805 SM/R_0805 SM/R_0805 SM/R_0805 XP4 P 8208 P E 68386
2005 Semtech Corp.
18
www.semtech.com
SC4910A/B
POWER MANAGEMENT Outline Drawing - TSSOP-20
A e N 2X E/2 E1 PIN 1 INDICATOR ccc C 1 2 3 2X N/2 TIPS E D
DIM
A A1 A2 b c D E1 E e L L1 N 01 aaa bbb ccc
DIMENSIONS MILLIMETERS INCHES MIN NOM MAX MIN NOM MAX
.047 .006 .002 .042 .031 .007 .012 .007 .003 .251 .255 .259 .169 .173 .177 .252 BSC .026 BSC .018 .024 .030 (.039) 20 8 0 .004 .004 .008 1.20 0.15 0.05 1.05 0.80 0.19 0.30 0.20 0.09 6.40 6.50 6.60 4.30 4.40 4.50 6.40 BSC 0.65 BSC 0.45 0.60 0.75 (1.0) 20 0 8 0.10 0.10 0.20
e/2 B D A2 A
aaa C SEATING PLANE
C bxN
A1 bbb C A-B D GAGE PLANE 0.25
H c L (L1) DETAIL
01
SIDE VIEW
NOTES: 1.
SEE DETAIL
A
A
CONTROLLING DIMENSIONS ARE IN MILLIMETERS (ANGLES IN DEGREES). AND -BTO BE DETERMINED AT DATUM PLANE -H-
2. DATUMS -A-
3. DIMENSIONS "E1" AND "D" DO NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS. 4. REFERENCE JEDEC STD MO-153, VARIATION AC.
Land Pattern - TSSOP-20
F
DIM
(C) H G Z C F G H P X Y Z
DIMENSIONS INCHES MILLIMETERS
(.222) .157 .161 .126 .026 .016 .061 .283 (5.65) 4.00 4.10 3.20 0.65 0.40 1.55 7.20
Y P
NOTES: 1.
X
THIS LAND PATTERN IS FOR REFERENCE PURPOSES ONLY. CONSULT YOUR MANUFACTURING GROUP TO ENSURE YOUR COMPANY'S MANUFACTURING GUIDELINES ARE MET.
Contact Information
Semtech Corporation Power Management Products Division 200 Flynn Road, Camarillo, CA 93012 Phone: (805)498-2111 FAX (805)498-3804
2005 Semtech Corp.
19
www.semtech.com

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