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PT4660 Series--48V
20-A Dual Output Isolated DC/DC Converter
SLTS140B - MAY 2001 - REVISED JANUARY 2003
Features
* Dual Outputs (Independantly Regulated) * Power-up/Down Sequencing * Input Voltage Range: 36V to 75V * 1500 VDC Isolation * Temp Range: -40 to 100C * High Efficiency: 88% * Fixed Frequency Operation * Over-Current Protection (Both Outputs) * Dual Logic On/Off Control * Over-Temperature Shutdown * Over-Voltage Protection (Coordinated Shutdown) * Under-Voltage Lockout * Input Differential EMI Filter * IPC Lead Free 2 * Safety Approvals: UL1950 CSA 22.2 950
Description
The PT4660 ExcaliburTM Series is a dual-output isolated DC/DC converter that combine state-of-theart power conversion technology with unparalleled flexibility. Operating from a standard telecom (-48V) central office supply, the PT4660 series provides up to 20 ADC of output current from two independently regulated voltages (each output 15 ADC max). The PT4660 series is characterized with high efficiencies and ultra-fast transient response, and incorporates many features to facilitate system integration. These include a flexible "On/Off" enable control, output current limit, over-temperature protection, and an input under-voltage lock-out. In addition both output voltages are designed to meet the power-up/power-down sequencing requirements of popular DSPs. The PT4660 series is housed in space-saving solderable copper case. The package does not require a heatsink and is available in both vertical and horizontal configurations, including surface mount. The `N' configuration occupies less than 2 in of PCB area.
Ordering Information
Pt. No. PT4661o PT4662o PT4663o PT4665o PT4666o PT4667o PT4668o = = = = = = = Vo1/Vo2 5.0/3.3 Volts 3.3/2.5 Volts 3.3/1.8 Volts 3.3/1.5 Volts 2.5/1.8 Volts 5.0/1.8 Volts 3.3/1.2 Volts
PT Series Suffix (PT1234 x )
Case/Pin Configuration Vertical Horizontal SMD Order Suffix Package Code (EKD) (EKA) (EKC)
N A C
(Reference the applicable package code drawing for the dimensions and PC board layout)
Typical Application
V 1 Adjust V 2 Adjust
20 Vo 2 adj 13 Vo 1 adj Vo 1 9-12
+ V IN
Vo 1 Vo 2
1
+Vin
Vo 2
21-24
PT4660
3 4 EN 1* EN 2 -Vin COM 14-19 L O A D L O A D
- V IN
2
COM
* Inverted logic
For technical support and more information, see inside back cover or visit www.ti.com
PT4660 Series--48V
20-A Dual Output Isolated DC/DC Converter
SLTS140B - MAY 2001 - REVISED JANUARY 2003
Pin-Out Information
Pin
1 2 3 4 5 6 7 8 9
On/Off Logic
Pin
10 11 12 13 14 15 16 17 18
Function
+Vin -Vin EN 1 EN 2 TEMP AUX Do Not Connect Do Not Connect +Vo1
Function
+Vo1 +Vo1 +Vo1 Vo1 Adjust COM COM COM COM COM
Pin
19 20 21 22 23 24 25 26
Function
COM Vo2 Adjust +Vo2 +Vo2 +Vo2 +Vo2 Do Not Connect Do Not Connect
Pin 3 1 0 x
Pin 4 x 1 0
Output Status Off On Off
Notes: Logic 1 =Open collector Logic 0 = -Vin (pin 2) potential For positive Enable function, connect pin 3 to pin 2 and use pin 4. For negative Enable function, leave pin 4 open and use pin 3.
Note: Shaded functions indicate signals that are referenced to the input (-Vin) potential.
Pin Descriptions
+Vin: The positive input supply for the module with respect to -Vin. When powering the module from a -48V telecom central office supply, this input is connected to the primary system ground. -Vin: The negative input supply for the module, and the 0VDC reference for the EN 1, EN 2, TEMP, and AUX signals. When the module is powered from a +48V supply, this input is connected to the 48-V Return. EN 1: An open-collector (open-drain) negative logic input that enables the module output. This pin is TTL compatible and referenced to -V in. A logic `0' at this pin enables the module's outputs. A logic `1' or high impedance disables the module's outputs. If not used, the pin must be connected to -Vin. EN 2: An open-collector (open-drain) positive logic input that enables the module output. This pin is TTL compatible and referenced to -Vin. A logic `1' or high impedance enables the module's outputs. If not used, the pin should be left open circuit. AUX: Produces a regulated output voltage of 11.6V 5%, which is referenced to -Vin. The current drawn from the pin must be limited to 10mA. The voltage may be used to indicate the output status of the module to a primary referenced circuit, or power a low-current amplifer. TEMP: This pin produces an output signal that tracks the module's metal case temperature. The output voltage is referenced to -Vin and rises approximately 10mV/C from an intital value of 0.1VDC at -40C. VTemp =0.5 + 0.01*TCase The signal is available whenever the module is supplied with a valid input voltage, and is independant of the enable logic status. (Note: A load impedance of less than 1M will adversly affect the module's over-temperature shutdown threshold. Use a high-impedance input when monitoring this signal.) Vo1: The higher regulated output voltage, which is referenced to the COM node. Vo2: The lower regulated output voltage, which is referenced to the COM node. COM: The secondary return reference for the module's two regulated output voltages. It is dc isolated from the input supply pins. Vo1 Adjust: Using a single resistor, this pin allows Vo1 to be adjusted higher or lower than the preset value. If not used, this pin should be left open circuit. Vo2 Adjust: Using a single resistor, this pin allows Vo2 to be adjusted higher or lower than the preset value. If not used, this pin should be left open circuit.
For technical support and more information, see inside back cover or visit www.ti.com
PT4660 Series--48V
20-A Dual Output Isolated DC/DC Converter
SLTS140B - MAY 2001 - REVISED JANUARY 2003
Specifications
Characteristics Output Current
(Unless otherwise stated, Ta =25C, Vin =48V, & Io 1=Io 2=10A) Symbols Io1 Io2 Io1+Io2 Vin Votol Regtemp Regline Regload Regcross Votol Conditions Vo1 Vo2 T otal (both outputs) Min 0 0 0 36 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 15.5 -- -- 270 -- 30 -- Referenced to -Vin VIH VIL IIL Iin standby Cout V iso C iso R iso Vtemp OTP Ta Treflow Ts -- -- -- -- Pins 2, 3, & 4 connected Per each output 3.5 0 -- -- 0 1500 -- 10 -- -- -- -40 -- -40 -- -- -- -- -- -- 0.5 3 -- -- 1500 -- 0.1 (5) 1.5 (5) 110 -- -- -- 500 10 (8) 20 (8) 90 -- 0.8 -- 5 5,000 -- -- -- -- -- -- +85 (6) 215 (7) +125 -- -- -- --
(4)
PT4660 SERIES Typ Max
-- -- -- 48 1 0.5 5 2 2 2 2 2 2 88 87 86 86 85 88 86 -- -- 25 6.0 18 (2) 5 125 (3) -- 34 32 2 15 15 20 (1) 75 2 -- 10 10 10 10 5 3 3 -- -- -- -- -- -- -- 75 50 100 -- -- 10 -- 330 36 -- --
Units A A V %Vo %Vo mV mV mV %Vo
Input Voltage Range Set Point Voltage T olerance Temperature Variation Line Regulation Load Regulation Cross Regulation Total Output Variation Efficiency
Vo Ripple (pk-pk) Transient Response Current Limit Output Rise Time Output Over-Voltage Protection Switching Frequency Under-Voltage-Lockout Internal Input Capacitance On/Off Control Input High Voltage Input Low Voltage Input Low Current Standby Current External Output Capacitance Primary/Secondary Isolation Temperature Sense Over-T emperature Shutdown Operating T emperature Range Solder Reflow Temperature Storage Temperature Mechanical Shock Mechanical Vibration Per Mil-STD-883D, 20-2,000Hz Weight Flammability
Vr ttr Ilim Von OVP fs UVLO Cin
Vo1 Vo2 Vo1 Vo2 Vo1 Vo2 PT4661 PT4662 PT4663 PT4665 PT4666 PT4667 PT4668 Io1=Io2=5A, 20MHz bandwidth Vo =5V Vo <5V 1A/s load step from 50% to 100% Iomax (either output) Each output with other unloaded At turn-on to within 90% of Vo Either output; shutdown and latch off Rising Falling
-40 to +100C Case, Io1 =Io2 =0A Over Vin range with Io1=Io2=5A 1A Io1 15A, Io2 =1A 1A Io2 15A, Io1 =1A 1A Io2 15A, Io1 =1A 1A Io1 15A, Io2 =1A Includes set-point, line load, -40C to +100C case
%
mVpp Sec %Vo A mSec %Vo kHz V F V mA mA F V pF M V C C C C G's G's grams
Output voltage at temperatures:-
-40C 100C
Case temperature (auto restart) Over Vin range Surface temperature of module pins or case -- Per Mil-STD-883D, Method 2002.3 Vertical Horizontal -- Materials meet UL 94V-0
Notes: (1) The sum-total current from Vo1 & Vo2 must not exceed 20ADC. (2) This figure is the inception of the current limit. Consult the application notes for further information on the current limit characteristics. (3) This is a fixed parameter. Adjusting Vo1 or Vo2 higher will increase the module's sensitivity to over-voltage detection. For more information, see the application note on output voltage adjustment. (4) The EN 1 and EN2 control inputs (pins 3 & 4) have internal pull-ups and may be controlled with an open-collector (or open-drain) transistor. Both inputs are diode protected and can be connected to +Vin . The maximum open-circuit voltage is 5.4V. (5) Voltage output at "TEMP" pin is defined by the equation:- VTEMP = 0.5 + 0.01*T, where T is in C. See pin descriptions for more information. (6) See SOA curves or consult the factory for the appropriate derating. (7) During solder reflow of SMD package version do not elevate the module case, pins, or internal component temperatures above a peak of 215C. For further guidance refer to the application note, "Reflow Soldering Requirements for Plug-in Power Surface Mount Products," (SLTA051). (8) The case pins on the through-holed package types (suffixes N & A) must be soldered. For more information see the applicable package outline drawing.
For technical support and more information, see inside back cover or visit www.ti.com
PT4661--48V
20-A Dual Output Isolated DC/DC Converter
Typical Characteristics
SLTS140B - MAY 2001 - REVISED JANUARY 2003
PT4661 (V1/V2 =5.0V/3.3V); Vin =48V
(See Notes A & B)
Efficiency vs I1out; I2out @1A, 3A, and 6A
100 12 90 10
Power Dissipation vs I1out and I2out
Efficiency - %
I2 out
80
I2 out
8
Pd - Watts
70
6 3 1
6
60
4
15 12 9 6 3 1
2 50 0 3 6 9 12 15 0 0 3 6 9 12 15
I1 out (A)
I1 out (A)
Efficiency vs I1out; I2out @9A, 12A, and 15A
100 90.0 80.0 90
Safe Operating Area: (I 1out =0-15A, I 2out =5Adc)
Ambient Temperature (C)
70.0 60.0 50.0 40.0 30.0
Efficiency - %
I2 out
80
Airflow 300LFM 200LFM 100LFM Nat conv
70
9 12 15
60
50 0 3 6 9 12 15
20.0 0.0 3.0 6.0 9.0 12.0 15.0
I1 out (A)
Io1 (A)
Cross Regulation: V1out vs I 2out @I1out =1A
5.05 90.0 80.0 5.025
Safe Operating Area: (I 1out =0-10A, I 2out =10Adc)
Ambient Temperature (C)
70.0 60.0 50.0 40.0 30.0
5
Airflow 300LFM 200LFM 100LFM Nat conv
V1 out (V)
4.975
4.95 0 3 6 9 12 15
20.0 0.0 2.0 4.0 6.0 8.0 10.0
I2 out (A)
Io1 (A)
Cross Regulation: V2out vs I 1out @I2out =1A
3.32 90.0 80.0 3.31
Safe Operating Area: (I 2out =0-15A, I 1out =5Adc)
Ambient Temperature (C)
70.0 60.0 50.0 40.0 30.0
3.3
Airflow 300LFM 200LFM 100LFM Nat conv
V2 out (V)
3.29
3.28 0 3 6 9 12 15
20.0 0.0 3.0 6.0 9.0 12.0 15.0
I1 out (A)
Io2 (A)
Note A: All Characteristic data in the above graphs has been developed from actual products tested at 25C. This data is considered typical data for the converter. Note B: SOA curves represent operating conditions at which internal components are at or below manufacturer's maximum rated operating temperatures.
For technical support and more information, see inside back cover or visit www.ti.com
PT4662--48V
20-A Dual Output Isolated DC/DC Converter
Typical Characteristics
SLTS140B - MAY 2001 - REVISED JANUARY 2003
PT4662 (V1/V2 =3.3V/2.5V); Vin =48V
(See Notes A & B)
Efficiency vs I1out; I2out @1A, 3A, and 6A
90 10
Power Dissipation vs I1out and I2out
8 85
I2 out 15 12 9 6 3 1
Efficiency - %
I2 out Pd - Watts
80
6 3 1
6
4
75 2
70 0 3 6 9 12 15
0 0 3 6 9 12 15
I1 out (A)
I1 out (A)
Efficiency vs I1out; I2out @9A, 12A, and 15A
90 90.0 80.0 85
Safe Operating Area: (I1out =0-15A, I 2out =5Adc)
Ambient Temperature (C)
Efficiency - %
I2 out
80
70.0 60.0 50.0 40.0 30.0
Airflow 300LFM 200LFM 100LFM Nat conv
9 12 15
75
70 0 3 6 9 12 15
20.0 0.0 3.0 6.0 9.0 12.0 15.0
I1 out (A)
I1 out (A)
Cross Regulation: V1out vs I 2out @I1out =1A
3.36 90.0 80.0 3.33
Safe Operating Area: (I1out =0-10A, I 2out =10Adc)
Ambient Temperature (C)
70.0 60.0 50.0 40.0 30.0
Airflow 300LFM 200LFM 100LFM Nat conv
V1 out (V)
3.30
3.27
3.24 0 3 6 9 12 15
20.0 0.0 2.0 4.0 6.0 8.0 10.0
I2 out (A)
I1 out (A)
Cross Regulation: V2out vs I 1out @I2out =1A
2.530 90.0 80.0 2.515
Safe Operating Area: (I2out =0-15A, I 1out =5Adc)
Ambient Temperature (C)
70.0 60.0 50.0 40.0 30.0
Airflow 300LFM 200LFM 100LFM Nat conv
V2 out (V)
2.500
2.485
2.470 0 3 6 9 12 15
20.0 0.0 3.0 6.0 9.0 12.0 15.0
I1 out (A)
I2 out (A)
Note A: All Characteristic data in the above graphs has been developed from actual products tested at 25C. This data is considered typical data for the converter. Note B: SOA curves represent operating conditions at which internal components are at or below manufacturer's maximum rated operating temperatures.
For technical support and more information, see inside back cover or visit www.ti.com
PT4663--48V
20-A Dual Output Isolated DC/DC Converter
Typical Characteristics
SLTS140B - MAY 2001 - REVISED JANUARY 2003
PT4663 (V1/V2 =3.3V/1.8V); Vin =48V
(See Notes A & B)
Efficiency vs I1out; I2out @1A, 3A, and 6A
90 10
Power Dissipation vs I1out and I2out
85
Efficiency - %
I2 out Pd - Watts
80
8
I2 out 15 12 9 6 3 1
6 3 1
6
4
75 2 70 0 3 6 9 12 15 0 0 3 6 9 12 15
I1 out (A)
I1 out (A)
Efficiency vs I 1out; I2out @9A, 12A, and 15A
90 90.0 85 80.0
Safe Operating Area: (I 1out =0-15A, I 2out =5Adc)
Efficiency - %
I2 out
80
Ambient Temperature (C)
70.0 60.0 50.0 40.0 30.0
9 12 15
Airflow 300LFM 200LFM 100LFM Nat conv
75
70 0 3 6 9 12 15 20.0 0.0 3.0 6.0 9.0 12.0 15.0
Iout (A)
I1 out (A)
Cross Regulation: V1out vs I 2out @I1out =1A
3.36 90.0 3.34 80.0 3.32
Safe Operating Area: (I 1out =0-10A, I 2out =10Adc)
Ambient Temperature (C)
V1 out (V)
70.0 60.0 50.0 40.0 30.0
Airflow 300LFM 200LFM 100LFM Nat conv
3.3
3.28
3.26
3.24 0 3 6 9 12 15
20.0 0.0 2.0 4.0 6.0 8.0 10.0
I2 out (A)
I1 out (A)
Cross Regulation: V2out vs I 1out @I2out =1A
1.82 90.0 80.0 1.81
Safe Operating Area: (I 2out =0-15A, I 1out =5Adc)
Ambient Temperature (C)
70.0 60.0 50.0 40.0 30.0 20.0
Airflow 300LFM 200LFM 100LFM Nat conv
V2 out (V)
1.8
1.79
1.78 0 3 6 9 12 15
0.0
3.0
6.0
9.0
12.0
15.0
I1 out (A)
I2 out (A)
Note A: All Characteristic data in the above graphs has been developed from actual products tested at 25C. This data is considered typical data for the converter. Note B: SOA curves represent operating conditions at which internal components are at or below manufacturer's maximum rated operating temperatures.
For technical support and more information, see inside back cover or visit www.ti.com
PT4665--48V
20-A Dual Output Isolated DC/DC Converter
Typical Characteristics
SLTS140B - MAY 2001 - REVISED JANUARY 2003
PT4665 (V1/V2 =3.3V/1.5V); Vin =48V
Efficiency vs I 1out; I2out @1A, 3A, and 6A
100 10
Power Dissipation vs I1out and I2out
90
8
I2 out 15 12 9 6 3 1
Efficiency - %
I2 out
80
Pd - Watts
70
6 3 1
6
4
60
2
50 0 3 6 9 12 15
0 0 3 6 9 12 15
I1 out (A)
I1 out (A)
Efficiency vs I 1out; I2out @9A, 12A, and 15A
100 90.0 80.0 90
Safe Operating Area: (I1out =0-15A, I 2out =5Adc)
Ambient Temperature (C)
Efficiency - %
I2 out
80
70.0 60.0 50.0 40.0 30.0 20.0
Airflow 300LFM 200LFM 100LFM Nat conv
70
9 12 15
60
50 0 3 6 9 12 15
0.0
3.0
6.0
9.0
12.0
15.0
I2 out (A)
I1 out (A)
Cross Regulation: V1out vs I 2out @I1out =1A
3.32 90.0 80.0 3.31
Safe Operating Area: (I1out =0-10A, I 2out =10Adc)
Ambient Temperature (C)
70.0 60.0 50.0 40.0 30.0
Airflow 300LFM 200LFM 100LFM Nat conv
V1 out (V)
3.3
3.29
3.28 0 3 6 9 12 15
20.0 0.0 2.0 4.0 6.0 8.0 10.0
I2 out (A)
I1 out (A)
Cross Regulation: V2out vs I 1out @I2out =1A
1.51 90.0 80.0 1.505
Safe Operating Area: (I 2out =0-15A, I 1out =5Adc)
Ambient Temperature (C)
70.0 60.0 50.0 40.0 30.0
Airflow 300LFM 200LFM 100LFM Nat conv
V2 out (V)
1.5
1.495
1.49 0 3 6 9 12 15
20.0 0.0 3.0 6.0 9.0 12.0 15.0
I1 out (A)
I2 out (A)
Note A: All Characteristic data in the above graphs has been developed from actual products tested at 25C. This data is considered typical data for the converter. Note B: SOA curves represent operating conditions at which internal components are at or below manufacturer's maximum rated operating temperatures.
For technical support and more information, see inside back cover or visit www.ti.com
PT4666--48V
20-A Dual Output Isolated DC/DC Converter
Typical Characteristics
SLTS140B - MAY 2001 - REVISED JANUARY 2003
PT4666 (V1/V2 =2.5V/1.8V); Vin =48V
Efficiency vs I1out; I2out @1A, 3A, and 6A
100 10
Power Dissipation vs I1out and I2out
90
8
I2 out 15 12 9 6 3 1
Efficiency - %
I2 out
80
Pd - Watts
70
6 3 1
6
4
60
2
50 0 3 6 9 12 15
0 0 3 6 9 12 15
I1 out (A)
I1 out (A)
Efficiency vs I1out; I2out @9A, 12A, and 15A
100 90 80
Safe Operating Area: (I 1out =0-15A, I 2out =5Adc)
Ambient Temperature (C)
90
Efficiency - %
I2 out
80
70 60 50 40 30
Airflow Nat conv 200LFM 100LFM 300LFM
70
9 12 15
60
50 0 3 6 9 12 15
20 0 3 6 9 12 15
I1 out (A)
Io1 (A)
Cross Regulation: V1out vs I2out @I1out =1A
2.52
2.51
V1 out (V)
2.5
2.49
2.48 0 3 6 9 12 15
I2 out (A)
Cross Regulation: V2out vs I1out @I2out =1A
1.81
1.805
V2 out (V)
1.8
1.795
1.79 0 3 6 9 12 15
I1 out (A)
Note A: All Characteristic data in the above graphs has been developed from actual products tested at 25C. This data is considered typical data for the converter. Note B: SOA curves represent operating conditions at which internal components are at or below manufacturer's maximum rated operating temperatures. For technical support and more information, see inside back cover or visit www.ti.com
PT4667--48V
20-A Dual Output Isolated DC/DC Converter
Typical Characteristics
SLTS140B - MAY 2001 - REVISED JANUARY 2003
PT4667 (V1/V2 =5V/1.8V); Vin =48V
Efficiency vs I 1out; I2out @1A, 3A, and 6A
100 12 10
Power Dissipation vs I1out and I2out
90
I2 out I2 out
8
80
70
6 3 1
6
4 60
15 12 9 6 3 1
Efficiency - %
Pd - Watts
2
50 0 3 6 9 12 15
0 0 3 6 9 12 15
I1 out (A)
I1 out (A)
Efficiency vs I 1out; I2out @9A, 12A, and 15A
100 90 80 90
Safe Operating Area: (I1out =0-15A, I 2out =5Adc)
Ambient Temperature (C)
70 60 50 40 30
Airflow Nat conv 100LFM 200LFM 300LFM
Efficiency - %
I2 out
80
70
9 12 15
60
50 0 3 6 9 12 15
20 0 3 6 9 12 15
I1 out (A)
Iout (A)
Cross Regulation: V1out vs I 2out @I1out =1A
5.02
5.01
V1 out (V)
5
4.99
4.98 0 3 6 9 12 15
I2 out (A)
Cross Regulation: V2out vs I 1out @I2out =1A
1.81
1.805
V2 out (V)
1.8
1.795
1.79 0 3 6 9 12 15
I1 out (A)
Note A: All Characteristic data in the above graphs has been developed from actual products tested at 25C. This data is considered typical data for the converter. Note B: SOA curves represent operating conditions at which internal components are at or below manufacturer's maximum rated operating temperatures.
For technical support and more information, see inside back cover or visit www.ti.com
PT4668--48V
20-A Dual Output Isolated DC/DC Converter
Typical Characteristics
SLTS140B - MAY 2001 - REVISED JANUARY 2003
PT4668 (V1/V2 =3.3V/1.2V); Vin =48V
Efficiency vs I1out; I2out @1A, 3A, and 6A
100 10
Power Dissipation vs I1out and I2out
90
8
I2 out 15 12 9 6 3 1
Efficiency - %
I2 out
80
Pd - Watts
70
6 3 1
6
4
60
2
50 0 3 6 9 12 15
0 0 3 6 9 12 15
I1 out (A)
I1 out (A)
Efficiency vs I1out; I2out @9A, 12A, and 15A
100
90
Efficiency - %
I2 out
80
70
9 12 15
60
50 0 3 6 9 12 15
I1 out (A)
Cross Regulation: V1out vs I 2out @I1out =1A
3.32
3.31
V1 out (V)
3.3
3.29
3.28 0 3 6 9 12 15
I2 out (A)
Cross Regulation: V2out vs I 1out @I2out =1A
1.21
1.205
V2 out (V)
1.2
1.195
1.19 0 3 6 9 12 15
I1 out (A)
Note A: All Characteristic data in the above graphs has been developed from actual products tested at 25C. This data is considered typical data for the converter. Note B: SOA curves represent operating conditions at which internal components are at or below manufacturer's maximum rated operating temperatures. For technical support and more information, see inside back cover or visit www.ti.com
Application Notes
PT3660, PT4660 & PT4680 Series
Operating Features & System Considerations for the PT3660/4660/4680 Dual-Output Converters
Over-Current Protection
The dual-outputs of the PT3660, PT4660, and PT4680 series of DC/DC converters have independent output voltage regulation and current limit control. Applying a load current in excess of the current limit threshold at either output will cause the respective output voltage to drop. However, the voltage at Vo2 is derived from Vo1. Therefore a current limit fault on Vo1 will also cause Vo2 to drop. Conversely, a current limit fault applied to Vo2 will only cause Vo2 voltage to drop, and Vo1 will remain in regulation. The current limit is continuous with some current foldback. This means that at short circuit, the value of the output current can be less than the rated output of the converter. This is to reduce power dissipation when a fault is present. As with any foldback-limited source, if a constant current load is applied to the converter with a value greater than the short-circuit current, the output voltage will not come up. Resistive and non-linear load circuits are not affected by this characteristic as long as the current at startup does not exceed the short-circuit current of the converter. The majority of low-voltage analog and digital applications are not affected by this restriction. However, when testing with an electronic load the constant resistance setting should be used. host system for diagnostic purposes. Consult the `Pin Descriptions' section of the data sheet for further information on this feature.
Under-Voltage Lock-Out
The Under-Voltage Lock-Out (UVLO) circuit prevents operation of the converter whenever the input voltage to the module is insufficient to maintain output regulation. The UVLO has approximately 2V of hysterisis. This is to prevent oscillation with a slowly changing input voltage. Below the UVLO threshold the module is off and the enable control inputs, EN1 and EN2 are inoperative.
Primary-Secondary Isolation
The PT4460/80 and PT3660 series of DC/DC converters incorporate electrical isolation between the input terminals (primary) and the output terminals (secondary). All converters are production tested to a withstand voltage of 1500VDC. The isolation complies with UL60950 and EN60950, and the requirements for operational isolation. This allows the converter to be configured for either a positive or negative input voltage source. The regulation control circuitry for these modules is located on the secondary (output) side of the isolation barrier. Control signals are passed between the primary and secondary sides of the converter via a proprietory magnetic coupling scheme. This eliminates the use of opto-couplers. The data sheet `Pin Descriptions' and `Pin-Out Information' provides guidance as to which reference (primary or secondary) that must be used for each of the external control signals.
Output Over-Voltage Protection
Each output is monitored for over voltage (OV). For fail safe operation and redundancy, the OV fault detection circuitry uses a separate reference to the voltage regulation circuits. The OV threshold is fixed, and set nominally 25% higher than the set-point output voltage. If either output exceeds the threshold, the converter is shutdown and must be actively reset. The OV protection circuit can be reset by momentarily turning the converter off. This is accomplished by either cycling one of the output enable control pins (EN1 or EN2), or by removing the input power to the converter. Note: If Vo1 or Vo2 is adjusted to a higher voltage, the margin between the respective steadystate output voltage and its OV threshold is reduced. This can make the module sensitive to OV fault detection, that may result from random noise and load transients.
Fuse Requirements
To comply with safety agency requirements, these converters must be operated with an external input fuse. A fast-acting 250-V fuse is required. Table 1-1 gives the recommended current rating for the product series being used.
Table 1-1; Recommended Fuse Rating Product Input Total Series Bus Iout
PT4660 PT4680 PT3660 48V 24V 48V 20A 20A 30A
Fuse Rating 7A 10A 7A
Over-Temperature Protection
The converter has an internal temperature sensor. At a case temperature of approximately 115C the converter will shut down, and will automatically restart when the temperature returns to about 100C. The analog voltage generated by the sensor is also made available at the TEMP output (pin 5), and can be monitored by the
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Application Notes
PT3660, PT4660 & PT4680 Series
Using the On/Off Enable Controls on the PT3660/ 4660/4680 Series of Dual-Output Converters
The PT3660/4660 (48V input) and PT4680 (24V input) series of dual-output DC/DC converters incorporate both positive and negative logic output enable controls. EN1 (pin 3) is the negative enable input, and EN2 (pin 4) is the positive enable input. Both inputs are TTL logic compatible, and are electrically referenced to -Vin (pin 2) on the primary (input) side of the converter. A pull-up resistor is not required, but may be added if desired. Adding a pull-up resistor from either EN1 or EN2, up to +Vin, will not damage the converter.
the outputs of the converter. An example of this configuration is detailed in Figure 2-2. Note: The converter will only produce and output voltage if a valid input voltage is applied to Vin.
Figure 2-2; Negative Enable Configuration
3
EN 1*
4
EN 2
1 =Outputs On
BSS138
PT4660
Automatic (UVLO) Power-Up
Connecting EN1 (pin 3) to -Vin (pin 2) and leaving EN2 (pin 4) open-circuit configures the converter for automatic power up. (See data sheet "Typical Application"). The converter control circuitry incorporates an "Under Voltage Lockout" (UVLO) function, which disables the output until the minimum specified input voltage is present (See data sheet Specifications). The UVLO circuitry ensures a clean transition during power-up and powerdown, allowing the converter to tolerate a slow-rising input voltage. For most applications EN1 and EN2, can be configured for automatic power-up.
- V IN
2
-Vin
On/Off Output Voltage Sequencing
The output voltages from these dual-output DC/DC converters are independantly regulated, and are internally sequenced to meet the power-up requirements of popular microprocessor and DSP chipsets. Figure 2-3 shows the waveforms from a PT4661 after the converter is enabled at t=0s. During power-up, the Vo1 and Vo 2 voltage waveforms typically track within 0.4V prior to Vo2 reaching regulation. The waveforms were measured with a 5-Adc resistive load at each output, and with a 48-VDC input source applied. The converter typically produces a fully regulated output within 25ms. The actual turn-on time will vary slightly with input voltage, but the power-up sequence is independent of the load at either output.
Positive Output Enable (Negative Inhibit)
To configure the converter for a positive enable function, connect EN1 (pin 3) to -Vin (pin 2), and apply the system On/Off control signal to EN2 (pin 4). In this configuration, a logic `0' (-Vin potential) applied to pin 4 disables the converter outputs. An example of this configuration is detailed in Figure 2-1.
Figure 2-1; Positive Enable Configuration
Figure 2-3; Vo1, Vo2 Power-Up Sequence
Vo1 (2V/Div)
3
EN 1*
Vo2 (2V/Div)
4
EN 2
PT4660
1 =Outputs Off
BSS138
IIN (0.5A/Div)
- V IN
2
-Vin
0
5
10
15
20
25
30
35
t (milliseconds)
Negative Output Enable (Positive Inhibit)
To configure the converter for a negative enable function, EN2 (pin 4) is left open circuit, and the system On/Off control signal is applied to EN1 (pin 3). A logic `0' (-Vin potential) must then be applied to pin 3 in order to enable
During turn-off, both outputs drop rapidly due to the discharging effect of actively switched rectifiers. The voltage at Vo 1 remains higher than Vo2 during this period. The discharge time is typically 100s, but will vary with the amount of external load capacitance.
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Application Notes
PT3660, PT4660 & PT4680 Series
Adjusting the Output Voltage of the PT3660, PT4660, and PT4680 Dual-Output Converters
The dual output voltages from the PT3660/PT4660 (48V Bus), and PT4680 (24V Bus) series of DC/DC converters can be independently adjusted by up to 10%, higher or lower than the factory trimmed pre-set voltage. The adjustment requires the addition of a single external resistor 1. Table 3-1 gives the adjustment range of Vo1 and Vo2 for each model in the series as V a(min) and V a(max). Vo1 Adjust Down: Add a resistor (R1), between pin 13 (Vo1 Adj) and pin 12 (Vo1) 2. Vo1 Adjust Up: To increase the output, add a resistor R2 between pin 13 (Vo1 Adj) and pin 14 (COM) 2, 4. Vo2 Adjust Down: Add a resistor (R3) between pin 20 (Vo2 Adj) and pin 21 (Vo2) 2. Vo2 Adjust Up: Add a resistor R4 between pin 20 (Vo2 Adj) and pin 19 (COM) 2, 4. Refer to Figure 3-1 and T able 3-2 for both the placement and value of the required resistor. Notes: 1. Adjust resistors are not required if Vo1 and Vo2 are to remain at their respective nominal set-point voltage. In this case, Vo1 Adj (pin 13) and Vo2 Adj (pin 20) are left open-circuit 2. Use only a single 1% resistor in either the (R1) or R2 location to adjust Vo1, and in the (R3) or R4 location to adjust Vo2. Place the resistor as close to the converter as possible.
Figure 3-1; Placement of Output Adjust Resistors
3. Vo2 must always be at least 0.3V lower than Vo1. 4. The over-voltage protection threshold is fixed, and is set nominally 25% above the set-point output voltage. Adjusting Vo1 or Vo2 higher will reduce the voltage margin between the respective steady-state output voltage and its over-voltage (OV) protection threshold. This could make the module sensitive to OV fault detection, as a result of random noise and load transients. Note: An OV fault is a latched condition that shuts down both outputs of the converter. The fault can only be cleared by cycling one of the Enable control pins (EN1* / EN2), or by momentarily removing the input power to the module. 5. Never connect capacitors to either the Vo1 Adj or Vo2 Adj pins. Any capacitance added to these control pins will affect the stability of the respective regulated output. The adjust up and adjust down resistor values can also be calculated using the following formulas. Be sure to select the correct formula parameter from Table 3-1 for the output and model being adjusted. (R1) or (R3) = Ro * (Va - Vr ) (Vo - Va) Ro * Vr Va - Vo - Rs k
R2 or R4
=
- Rs
k
Where: Vo Va Vr Ro Rs
= = = = =
Original output voltage, (Vo1 or Vo2) Adjusted output voltage The reference voltage from Table 3-1 The resistance constant in Table 3-1 The series resistance from Table 3-1
+ V IN
Vo 1 1 +Vin Vo 2
9-12 21-24
V o1 V o2
PT4660
V o 1 adj 3 4 EN 1* EN 2 -Vin V o 2 adj 13 20
(R1)
(R3)
L O A D
L O A D
- V IN
2
R2
14-19
R4 COM
COM * Inverted logic
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Application Notes continued
PT3660, PT4660 & PT4680 Series
Table 3-1; ADJUSTMENT RANGE AND FORMULA PARAMETERS
Vo1 Bus 24V Bus Pt.# 48V Bus Pt.# Adj. Resistor Vo(nom) Va(min) Va(max) Vr Ro (k) Rs (k) PT4681/7 PTx661/7 (R1)/R2 5.0V 4.5V 5.5V 2.5V 4.99 20.0 PT4682/3/5/8 PTx662/3/5/8 (R1)/R2 3.3V 2.97V 3.63V 1.65V 4.99 20.0 PT4686 PTx666 (R1)/R2 2.5V 2.25V 2.75V 1.25 4.99 20.0 Vo2 Bus (2) PT4681 PTx661 (R3)/R4 3.3V 2.97V 3.63V 1.65V 1.21 4.99 PT4682 PTx662 (R3)/R4 2.5V 2.25V 2.75V 1.25V 1.21 4.99 PT4683/7 PTx663/7 (R3)/R4 1.8V 1.62V 1.98V 0.9V 1.21 4.99 PT4686 PTx666 (R3)/R4 1.8V 1.62V 1.98V 0.9V 1.21 3.32 PT4685 PTx665 (R3)/R4 1.5V 1.35 1.65 0.75 1.21 4.99 PT4688 PTx668 (R3)/R4 1.2V 1.08 1.32 0.6V 1.21 3.32
Table 3-2a; ADJUSTMENT RESISTOR VALUES, Vo1
24V Bus Pt.# PT4681/7 48V Bus Pt.# PTx661/7 Adj. Resistor (R1)/R2 Vo(nom) Va(req'd) 5.5 5.4 5.3 5.2 5.1 5.0 4.9 4.8 4.7 4.6 4.5 5.0V 5.0k 11.2k 21.6k 42.4k 105.0k (99.8)k (37.4)k (16.6)k (6.2)k (0.0) Va(req'd) 3.6 3.54 3.48 3.42 3.36 3.3 3.24 3.18 3.12 3.06 3.0 PT4682/3/5/8 PTx662/3/5/8 (R1)/R2 3.3V 7.4k 14.3k 25.7k 48.6k 117.0k (112.0k) (43.6k) (20.8k) (9.3k) (2.5k) Va(req'd) 2.75 2.7 2.65 2.6 2.55 2.5 2.45 2.4 2.35 2.3 2.25 PT4686 PTx666 (R1)/R2 2.5V 5.0k 11.2k 21.6k 42.4k 105.0k (99.8k) (37.4k) (16.6k) (6.2k) (0.0k)
R1 = (Blue), R2 = Black
Table 3-2b; ADJUSTMENT RESISTOR VALUES, Vo2
24V Bus Pt.# 48V Bus Pt.# Adj. Resistor Vo(nom) Va(req'd) 3.6 3.54 3.48 3.42 3.36 3.3 3.24 3.18 3.12 3.06 3.0 2.75 2.7 2.65 2.6 2.55 2.5 2.45 2.4 2.35 2.3 2.25 PT4681 PTx661 (R3)/R4 3.3V 1.7k 3.3k 6.1k 11.6k 28.3k (27.1)k (10.4)k (4.9)k (2.1)k (0.5)k 1.1k 2.6k 5.1k 10.1k 25.3k (24.1)k (8.9)k (3.9)k (1.4)k (0.0)k PT4682 PTx662 (R3)/R4 2.5V Va(req'd) 1.95 1.9 1.85 1.8 1.75 1.7 1.65 1.6 1.55 1.5 1.45 1.4 1.35 1.3 1.275 1.25 1.225 1.2 1.175 1.15 1.125 1.1 PT4683/6/7 PTx663/6/7 (R3)/R4 1.8V 2.3k 5.9k 16.8k (15.6)k (4.7)k (1.1)k PT4686 PTx666 (R3)/R4 1.8V 3.9k 7.6k 18.5k (17.3)k (6.4)k (2.7)k PT4685 PTx665 (R3)/R4 1.5V PT4688 PTx668 (R3)/R4 1.2V
1.1k 4.1k 13.2k (12.0)k (2.9)k (0.0)k 3.9k 6.4k 11.2k 25.7k (24.5)k (10.0)k (5.2)k (2.7)k
R3 = (Blue), R4 = Black
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