PT3661

PT3663 TI | Alldatasheet

Document overview

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Technical content

Features

• Dual Outputs (Independantly Regulated)
• Power-up/Down Sequencing
• Input Voltage Range: 36V to 75V
• 1500 VDC Isolation
• Temp Range: –40° to 100°C
• High Efficiency: 88%
• Fixed Frequency Operation
• Over-Current Protection (Both Outputs)

Ordering Information

Pt. No. Vo 1/Vo2 PT3661/G6F= 5.0/3.3 Volts PT3662/G6F= 3.3/2.5 Volts PT3663/G6F= 3.3/1.8 Volts PT3665/G6F= 3.3/1.5 Volts PT3666/G6F= 2.5/1.8 Volts PT3667/G6F= 5.0/1.8 Volts PT3668/G6F= 3.3/1.2 Volts Typical Application PT3660 +Vin EN 1* EN 2 –Vin Vo 1 ad jVo 2 ad j Vo 1 Vo 2 COM 9–12 21–24 14–19 L O A D L O A D Vo 1 Vo 2 V 1 Adjust V 2 Adjust +V IN –V IN 20 13

2 COM

• Inverted logic
• Dual Logic On/Off Control
• Over-Temperature Shutdown
• Over-Voltage Protection (Coordinated Shutdown)
• Under-Voltage Lockout
• Input Differential EMI Filter
• Solderable Copper Case
• Safety Approvals: UL1950 CSA 22.2 950 protection, and an input under- voltage lockout. In addition, both output voltages are designed to meet the power-up/power-down sequenc- ing requirements of popular DSP ICs. The PT3660 series is housed in space-saving solderable copper case. The package does not require a heatsink and is available in both vertical and horizontal configura- tions, including surface mount. The ‘N’ configuration occupies less than 2 in² of PCB area. This product is pin-compatible with the PT4660 series. PT Series Suffix (PT1234x) Case/Pin Order Package Configuration Suffix Code Vertical N (EKD) Horizontal A (EKA) SMD C (EKC) (Reference the applicable package code draw- ing for the dimensions and PC board layout)

For technical support and more information, see inside back cover or visit www.ti.com ADVANCE INFORMATION SL TS181 OCTOBER 2002 PT3660 Series 30-A Dual Output Isolated DC/DC Converter 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 48V–Return. EN 1: The 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 –V in. EN 2: The positive logic input that enables the module output. This pin is TTL compatible and referenced to –V in. A logic ‘1’ or high impedance enables the module’s outputs. If not used, the pin should be left open circuit. TEMP: This is the output voltage produced by the module’s internal temperature sensor. The voltage at this pin is referenced to –V in and rises approximately 10mV/°C from an intital value of 0.1VDC at –40°C (Vtemp =0.5 + 0.01·T sense). 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 Ω will adversly affect the module’s over-temperature shutdown threshold. Use a high-impedance input when monitoring this signal.) AUX: Produces a regulated output voltage of 11.6V ±5%, which is referenced to –V in. 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. Vo 1: 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. Vo

1 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. On/Off Logic Pin 3 Pin 4 Output Status 1 × Off

01 O n

× 0 Off Pin-Out Information Pin Function 1+ V in 2- V in

3 EN 1

4 EN 2

5 TEMP

6 AUX

7 Do Not Connect

8 Do Not Connect

13 Vo 1 Adjust

14 COM

15 COM

16 COM

17 COM

18 COM

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 Function

19 COM

20 Vo 2 Adjust

25 Do Not Connect

26 Do Not Connect

For technical support and more information, see inside back cover or visit www.ti.com ADVANCE INFORMATION SL TS181 OCTOBER 2002 PT3660 Series 30-A Dual Output Isolated DC/DC Converter Specifications (Unless otherwise stated, T a =25°C, Vin =48V, & Io1=Io2=10A) PT3660 SERIES Characteristics Symbols Conditions Min Typ Max Units Output Current Io 1, Io2 Vo1 Vo1 ≤3.3V 0 — 15 AVo1 =5.0V 0 — 10 Vo2 All voltages 0 — 15 A Io1+Io2 Total (both outputs) Vo 1 ≤3.3V 0 — 30 AVo1 =5.0V 0 — 25 Input Voltage Range V in 36 48 75 V Set Point Voltage Tolerance V ot o l —± 1± 2% V o Temperature Variation ∆Regtemp –40 to +100°C Case, Io1 =Io2 =0A — ±0.5 — %V o Line Regulation ∆Regline Over Vin range with Io1=Io2=5A — ±5 ±10 mV Load Regulation ∆Regload 1A ≤Io1 ≤Io1max, Io2 =1A ∆Vo1 — ±2 ±10 mV1A ≤Io2 ≤Io1max, Io1 =1A ∆Vo2 — ±2 ±10 Cross Regulation ∆Regcross 1A ≤Io2 ≤Io1max, Io1 =1A ∆Vo1 — ±2 ±10 mV1A ≤Io1 ≤Io1max, Io2 =1A ∆Vo2 —± 2± 5 Total Output Variation ∆Votol Includes set-point, line load, ∆Vo1 —± 2± 3 %Vo–40°C to +100°C case ∆Vo2 —± 2± 3 Efficiency η PT3661 — 88 — PT3662 — 87 — PT3663 — 86 — PT3665 — 86 — % PT3666 — 85 — PT3667 — 88 — PT3668 — 86 — Vo Ripple (pk-pk) V r Io1=Io2=5A, 20MHz bandwidth V o =5V — — 75 mVppVo <5V — — 50 Transient Response t tr 1A/µs load step from 50% to 100% Iomax — 25 100 µSec (either output) — 6.0 — %V o Current Limit I LIM Each output with other unloaded 15.5 18 — A Output Rise Time t on At turn-on to within 90% of Vo — 5 10 mSec Output Over-Voltage Protection OVP Either output; shutdown and latch off — 125 (1) —% V o Switching Frequency f s 280 — 320 kHz Under-Voltage-Lockout UVLO Rising — 34 36 VFalling 30 32 — Internal Input Capacitance C in —2 —µ F On/Off Control Referenced to –V in Input High Voltage V IH 3.5 — — V Input Low Voltage V IL 0 — 0.8 (2) Input Low Current I IL — 0.5 — mA Standby Current I in standby Pins 2, 3, & 4 connected — 3 5 mA External Output Capacitance C out Per each output 0 — 5,000 µF Primary/Secondary Isolation V iso 1500 — — V C iso — 1500 — pF R iso 1 0——M Ω Temperature Sense V temp Output voltage at temperatures:- –40°C — 0.1 (3) — V100°C — 1.5 (3) — Operating Temperature Range T a Over Vin range –40 — 85 (4) °C Over-Temperature Protection OTP Case temperature (auto restart) 100 — — °C Solder Reflow Temperature T reflow Surface temperature of module pins or case — — 215 (5) °C Storage Temperature T s — –40 — 125 °C Mechanical Shock — Per Mil-STD-883D, Method 2002.3 — 500 — G’s Mechanical Vibration — Per Mil-STD-883D, Method 2007.2, Suffix N — 10 (6) — G’s 20–2,000Hz Suffixes A, C — 20 (6) — Weight — — — 90 — grams Flammability — Materials meet UL 94V-0 Notes: (1) This is a fixed parameter. Adjusting Vo 1 or Vo2 higher will increase the module’s sensitivity to over-voltage detection. For more information, see the application note on output voltage adjustment. (2) The EN1 and EN2 control inputs (pins 3 & 4) have internal pull-ups and may be controlled with an open-collector (or open-drain) transistor. Bo th inputs are diode protected and can be connected to +V in. The maximum open-circuit voltage is 5.4V. (3) Voltage output at “TEMP” pin is defined by the equation:- V TEMP = 0.5 + 0.01·T, where T is in °C. See pin descriptions for more information. (4) See SOA curves or consult the factory for the appropriate derating. (5) During solder reflow of SMD package version do not elevate the module case, pins, or internal component temperatures above a peak of 215°C. For further guidance refer to the application note, “Reflow Soldering Requirements for Plug-in Power Surface Mount Products,” (SLTA 051). (6) 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 ADVANCE INFORMATION SL TS181 OCTOBER 2002 Note A: All Characteristic data in the above graphs has been developed from actual products tested at 25°C. This data is considered typ ical data for the converter. Note B: SOA curves represent operating conditions at which internal components are at or below manufacturer’s maximum rated operating t emperatures. PT3661 30-A Dual Output Isolated DC/DC Converter Typical Characteristics PT3661 (V1/V2 =5.0V/3.3V); Vin =48V (See Notes A & B) Efficiency vs I1out; I2out @1A, 3A, and 6A Power Dissipation vs (Io 1 + Io2) Cross Regulation: V 1out vs I2out @I1out =1A Cross Regulation: V 2out vs I1out @I2out =1A Efficiency vs I1out; I2out @9A, 12A, and 15A Safe Operating Area: (Io 1 + Io2) 4.95 4.975 5.025 5.05 0369 1 2 1 5 I2 out (A ) V1 out (V) 3.28 3.29 3.3 3.31 3.32 0369 1 2 1 5 I1 out (A ) V2 out (V) 0 5 10 15 20 25 30 Io1 + Io2 (A) Ambient Temperature (°C) 300LFM 200LFM 100LFM Nat conv Airflow 100 0369 1 2 1 5 I1 out (A ) Efficiency - % I2 out 100 0369 1 2 1 5 I1 out (A ) Efficiency - % I2 out 0 6 12 18 24 30 Io1 + Io2 (A ) Pd - Watts

For technical support and more information, see inside back cover or visit www.ti.com ADVANCE INFORMATION SL TS181 OCTOBER 2002 PT3662—48V 30-A Dual Output Isolated DC/DC Converter Note A: All Characteristic data in the above graphs has been developed from actual products tested at 25°C. This data is considered typ ical data for the converter. Note B: SOA curves represent operating conditions at which internal components are at or below manufacturer’s maximum rated operating t emperatures. PT3662 (V1/V2 =3.3V/2.5V); Vin =48V (See Notes A & B) Efficiency vs I1out; I2out @1A, 3A, and 6A Power Dissipation vs (Io 1 + Io2) Cross Regulation: V 1out vs I2out @I1out =1A Cross Regulation: V 2out vs I1out @I2out =1A 2.470 2.485 2.500 2.515 2.530 0369 1 2 1 5 I1 out (A ) V2 out (V) 3.24 3.27 3.30 3.33 3.36 0369 1 2 1 5 I2 out (A ) V1 out (V) Efficiency vs I1out; I2out @9A, 12A, and 15A Safe Operating Area: (Io 1 + Io2) Typical Characteristics 0 5 10 15 20 25 30 Io1 + Io2 (A) Ambient Temperature (°C) 300LFM 200LFM 100LFM Nat conv Airflow 0 3 6 9 12 15 I1 out (A) Efficiency - % I2 out 0369 1 2 1 5 I1 out (A) Efficiency - % I2 out 0 6 12 18 24 30 Io1 + Io2 (A) Pd - Watts

For technical support and more information, see inside back cover or visit www.ti.com ADVANCE INFORMATION SL TS181 OCTOBER 2002 Note A: All Characteristic data in the above graphs has been developed from actual products tested at 25°C. This data is considered typ ical data for the converter. Note B: SOA curves represent operating conditions at which internal components are at or below manufacturer’s maximum rated operating t emperatures. PT3663— 48V 30-A Dual Output Isolated DC/DC Converter Typical Characteristics PT3663 (V1/V2 =3.3V/1.8V); Vin =48V (See Notes A & B) Efficiency vs I1out; I2out @1A, 3A, and 6A Power Dissipation vs (Io 1 + Io2) Cross Regulation: V 1out vs I2out @I1out =1A Cross Regulation: V 2out vs I1out @I2out =1A Efficiency vs I 1out; I2out @9A, 12A, and 15A Safe Operating Area: (Io 1 + Io2) 3.24 3.26 3.28 3.3 3.32 3.34 3.36 0369 1 2 1 5 I2 out (A ) V1 out (V) 1.78 1.79 1.8 1.81 1.82 0369 1 2 1 5 I2 out (A ) V1 out (V) 0 5 10 15 20 25 30 Io1 + Io2 (A) Ambient Temperature (°C) 300LFM 200LFM 100LFM Nat Conv Airflow 0369 1 2 1 5 I1 out (A ) Efficiency - % I2 out 0369 1 2 1 5 Iout (A ) Efficiency - % I2 out 0 6 12 18 24 30 Io1 + Io2 (A) Pd - Watts

For technical support and more information, see inside back cover or visit www.ti.com ADVANCE INFORMATION SL TS181 OCTOBER 2002 PT3665— 48V 30-A Dual Output Isolated DC/DC Converter Efficiency vs I 1out; I2out @1A, 3A, and 6A Power Dissipation vs (Io 1 + Io2) Cross Regulation: V 1out vs I2out @I1out =1A Cross Regulation: V 2out vs I1out @I2out =1A Efficiency vs I 1out; I2out @9A, 12A, and 15A Safe Operating Area: (Io 1 + Io2) Typical Characteristics PT3665 (V1/V2 =3.3V/1.5V); Vin =48V (See Notes A & B) Note A: All Characteristic data in the above graphs has been developed from actual products tested at 25°C. This data is considered typ ical data for the converter. Note B: SOA curves represent operating conditions at which internal components are at or below manufacturer’s maximum rated operating t emperatures. 3.28 3.29 3.3 3.31 3.32 0369 1 2 1 5 I2 out (A) V1 out (V) 1.49 1.495 1.5 1.505 1.51 0369 1 2 1 5 I1 out (A ) V2 out (V) 0 5 10 15 20 25 30 Io1 + Io2 (A) Ambient Temperature (°C) 300LFM 200LFM 100LFM Nat Conv Airflow 100 0369 1 2 1 5 I1 out (A ) Efficiency - % I2 out 100 0369 1 2 1 5 I2 out (A ) Efficiency - % I2 out 0 6 12 18 24 30 Io1 + Io2 (A) Pd - Watts

For technical support and more information, see inside back cover or visit www.ti.com ADVANCE INFORMATION SL TS181 OCTOBER 2002 Note A: All Characteristic data in the above graphs has been developed from actual products tested at 25°C. This data is considered typ ical data for the converter. Note B: SOA curves represent operating conditions at which internal components are at or below manufacturer’s maximum rated operating t emperatures. PT3666 (V1/V2 =2.5V/1.8V); Vin =48V (See Notes A & B) PT3666— 48V 30-A Dual Output Isolated DC/DC Converter Typical Characteristics Efficiency vs I1out; I2out @1A, 3A, and 6A Power Dissipation vs I 1out and I2out Cross Regulation: V 1out vs I2out @I1out =1A Cross Regulation: V 2out vs I1out @I2out =1A Efficiency vs I1out; I2out @9A, 12A, and 15A Safe Operating Area: (Io 1 + Io2) 2.48 2.49 2.5 2.51 2.52 0369 1 2 1 5 I2 out (A) V1 out (V) 1.79 1.795 1.8 1.805 1.81 0369 1 2 1 5 I1 out (A) V2 out (V) 0 5 10 15 20 25 30 Io1 + Io2 (A) Ambient Temperature (°C) 300LFM 200LFM 100LFM Nat Conv Airflow 100 0369 1 2 1 5 I1 out (A ) Efficiency - % I2 out 100 0 3 6 9 12 15 I1 out (A ) Efficiency - % I2 out 0369 1 2 1 5 Io1 + Io2 (A) Pd - Watts

For technical support and more information, see inside back cover or visit www.ti.com ADVANCE INFORMATION SL TS181 OCTOBER 2002 PT3667— 48V 30-A Dual Output Isolated DC/DC Converter Efficiency vs I 1out; I2out @1A, 3A, and 6A Power Dissipation vs (Io 1 + Io2) Cross Regulation: V 1out vs I2out @I1out =1A Cross Regulation: V 2out vs I1out @I2out =1A Efficiency vs I 1out; I2out @9A, 12A, and 15A Safe Operating Area: (Io 1 + Io2) Typical Characteristics PT3667 (V1/V2 =5V/1.8V); Vin =48V (See Notes A & B) Note A: All Characteristic data in the above graphs has been developed from actual products tested at 25°C. This data is considered typ ical data for the converter. Note B: SOA curves represent operating conditions at which internal components are at or below manufacturer’s maximum rated operating t emperatures. 4.98 4.99 5.01 5.02 0369 1 2 1 5 I2 out (A) V1 out (V) 1.79 1.795 1.8 1.805 1.81 0369 1 2 1 5 I1 out (A) V2 out (V) 0 5 10 15 20 25 30 Io1 + Io2 (A) Ambient Temperature (°C) 300LFM 200LFM 100LFM Nat conv Airflow 100 0369 1 2 1 5 I1 out (A ) Efficiency - % I2 out 100 0 3 6 9 12 15 I1 out (A ) Efficiency - % I2 out 0 6 12 18 24 30 Io1 + Io2 (A) Pd - Watts

For technical support and more information, see inside back cover or visit www.ti.com ADVANCE INFORMATION SL TS181 OCTOBER 2002 Note A: All Characteristic data in the above graphs has been developed from actual products tested at 25°C. This data is considered typ ical data for the converter. Note B: SOA curves represent operating conditions at which internal components are at or below manufacturer’s maximum rated operating t emperatures. PT3668 (V1/V2 =3.3V/1.2V); Vin =48V (See Notes A & B) PT3668— 48V 30-A Dual Output Isolated DC/DC Converter Typical Characteristics Efficiency vs I1out; I2out @1A, 3A, and 6A Power Dissipation vs (Io 1 + Io2) Cross Regulation: V 1out vs I2out @I1out =1A Cross Regulation: V 2out vs I1out @I2out =1A Efficiency vs I1out; I2out @9A, 12A, and 15A 3.28 3.29 3.3 3.31 3.32 0369 1 2 1 5 I2 out (A) V1 out (V) 1.19 1.195 1.2 1.205 1.21 0369 1 2 1 5 I1 out (A) V2 out (V) 0 5 10 15 20 25 30 Io1 + Io2 (A) Ambient Temperature (°C) 300LFM 200LFM 100LFM Nat Conv Airflow Safe Operating Area: (Io 1 + Io2) 100 0 3 6 9 12 15 I1 out (A ) Efficiency - % I2 out 100 0 3 6 9 12 15 I1 out (A ) Efficiency - % I2 out 0 6 12 18 24 30 Io1 + Io2 (A) Pd - Watts

For technical support and more information, see inside back cover or visit www.ti.com 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 V o 2 is derived from Vo 1. Therefore a current limit fault on V o 1 will also cause Vo2 to drop. Conversely, a current limit fault applied to Vo 2 will only cause Vo 2 voltage to drop, and Vo 1 will remain in regulation. The current limit circuitry incorporates a limited amount of foldback. The fault current flowing into an absolute short circuit is therefore slightly less than the current limit threshold. Recovery from a current limit fault is automatic and the converter will not be damaged by a continuous short circuit at either output. 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 regula- tion 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 EN 2), 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 steady- state 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. Over-Temperature Protection The converter has an internal temperature sensor. At a case temperature of approximately 115°C the converter will shut down, and will automatically restart when the temperature returns to about 100°C. The analog voltage generated by the sensor is also made available at the ‘TEMP’ output (pin 5), and can be monitored by the host system for diagnostic purposes. Consult the ‘Pin Descriptions’ section of the data sheet for further infor- mation 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 volt- age. 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 termi- nals (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. Fuse Requirements T o comply with safety agency requirements, these con- verters must be operated with an external input fuse. A fast-acting 250-V fuse is required. T able 1-1 gives the recommended current rating for the product series being used. Table 1-1; Recommended Fuse Rating Product Input Total Fuse Series Bus Iout Rating PT4660 48V 20A 7A PT4680 24V 20A 10A PT3660 48V 30A 7A

For technical support and more information, see inside back cover or visit www.ti.com 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. T able 3-1 gives the adjustment range of Vo 1 and Vo2 for each model in the series as V a(min) and Va(max). Vo1 Adjust Down: Add a resistor (R1), between pin 13 (V1 Adj) and pin 12 (Vo1) 2. Vo1 Adjust Up: T o increase the output, add a resistor R2 between pin 13 (V1 Adj) and pin 14 (COM) 2, 4. Vo2 Adjust Down: Add a resistor (R3) between pin 20 (V2 Adj) and pin 21 (Vo2) 2. Vo2 Adjust Up: Add a resistor R 4 between pin 20 (V2 Adj) and pins 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 Vo 1 and Vo2 are to remain at their respective nominal set-point voltage. In this case, V 1 Adj (pin 13) and V 2 Adj (pin 20) are left open-circuit 2.Use only a single 1% resistor in either the (R1) or R2 location to adjust Vo 1, 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.Vo 2 must always be at least 0.3V lower than Vo 1. 4. The over-voltage protection threshold is fixed, and is set nominally 25% above the set-point output voltage. Adjusting Vo 1 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 tran- sients. 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 (EN 1* / EN2), or by momentarily removing the input power to the module. 5.Never connect capacitors to either the Vo 1 Adjust or Vo2 Adjust 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 T able 3-1 for the output and model being adjusted. (R1) or (R3) = Ko (Va – Vr ) – Rs kΩ Vr (Vo – Va) R2 or R4 = Ko – Rs kΩ Va – Vo Where: V o = Original output voltage, (Vo1 or Vo2) Va = Adjusted output voltage Vr = The reference voltage from T able 3-1 Ko = The multiplier constant in T able 3-1 Rs = The series resistance from T able 3-1 PT3660, PT4660 & PT4680 Series PT4660 +Vin EN 1* EN 2 –Vin Vo 1 adj Vo 2 adj Vo 1 Vo 2 COM 9 – 12 21 – 24 14 – 19 L O A D L O A D Vo 1 Vo 2 +V IN – V IN COM * Inverted logic (R1) (R3)

For technical support and more information, see inside back cover or visit www.ti.com Application Notes continued 5.5 5.0k Ω 5.4 11.2k Ω 5.3 21.6k Ω 5.2 42.4k Ω 5.1 105.0k Ω 5.0 4.9 (99.8)kΩ 4.8 (37.4)kΩ 4.7 (16.6)kΩ 4.6 (6.2)kΩ 4.5 (0.0) R1/R3 = (Blue), R2/R4 = Black Table 3-2a; ADJUSTMENT RESISTOR VALUES, Vo 1 24V Bus Pt.# PT4681/7 PT4682/3/5 PT4688 PT4686 48V Bus Pt.# PT4661/7 PT4662/3/5 PT4668 PT4666 Adj. Resistor (R1)/R2 (R1)/R2 (R1)/R2 (R1)/R2 Vo(nom) 5.0V 3.3V 3.3V 2.5V Va(req’d) V a(req’d) V a(req’d) Table 3-1; ADJUSTMENT RANGE AND FORMULA PARAMETERS Vo1 Bus Vo 2 Bus (2) 24V Bus Pt.# PT4681/7 PT4682/3/5 PT4688 PT4686 PT4681 PT4682 PT4683/6/7 PT4685 PT4688 48V Bus Pt.# PT4661/7 PT4662/3/5 PT4668 PT4666 PT4661 PT4662 PT4663/6/7 PT4665 PT4668 Adj. Resistor (R1)/R2 (R1)/R2 (R1)/R2 (R1)/R2 (R3)/R4 (R3)/R4 (R3)/R4 (R3)/R4 (R3)/R4 PT3660, PT4660 & PT4680 Series 3.6 7.4k Ω 31.5kΩ 3.54 14.3k Ω 40.7kΩ 3.48 25.7k Ω 55.9kΩ 3.42 48.6k Ω 86.3kΩ 3.36 117.0k Ω 178.0kΩ 3.3 1.95 9.4k Ω 1.9 15.7k Ω 1.85 34.7k Ω 1.8 1.75 (3.0)kΩ 1.7

1.65 TBD

1.6 TBD

1.55 TBD

1.5 1.45 (TBD) 1.4 (TBD) 1.35 (TBD) 1.3 3.0k Ω 1.275 5.5k Ω 1.25 10.3k Ω 1.225 24.8k Ω 1.2 1.175 (23.6)kΩ 1.15 (9.1)kΩ 1.125 (4.3)kΩ 1.1 (1.8)kΩ Table 3-2b; ADJUSTMENT RESISTOR VALUES, Vo 2 24V Bus Pt.# PT4681 PT4682 PT4683/6/7 PT4685 PT4688 48V Bus Pt.# PT4661 PT4662 PT4663/6/7 PT4665 PT4668 Adj. Resistor (R3)/R4 (R3)/R4 (R3)/R4 (R3)/R4 (R3)/R4 Va(req’d) V a(req’d) 3.6 1.0k Ω 3.54 2.5k Ω 3.48 5.0k Ω 3.42 10.0k Ω 3.36 25.0k Ω 3.3 3.24 (29.8)kΩ 3.18 (11.8)kΩ 3.12 (5.8)kΩ 3.06 (2.8)kΩ 3.0 (1.0)kΩ 2.75 4.7k Ω 2.7 6.7k Ω 2.65 10.0k Ω 2.6 16.7k Ω 2.55 36.7k Ω 2.5 2.45 (22.0)kΩ 2.4 (8.7)kΩ 2.35 (4.2)kΩ 2.3 (2.0)kΩ 2.25 (0.7)kΩ R1/R3 = (Blue), R2/R4 = Black 2.75 5.0k Ω 2.7 11.2k Ω 2.65 21.6k Ω 2.6 42.4k Ω 2.55 105.0k Ω 2.5 2.45 (99.8kΩ ) 2.4 (37.4kΩ ) 2.35 (16.6kΩ ) 2.3 (6.2kΩ ) 2.25 (0.0kΩ )

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