Application Notes

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PT4310 Series

Using the Remote On/Off Function on the

PT4310 Isolated Dual Output DC/DC Converters

For applications requiring output voltage On/Off control,

the PT4310 DC/DC converter series incorporates a

“Remote On/Off” control (pin 11). This feature can be used

when there is a requirement for the module to be switched

off without removing the applied input source voltage.

The converter operates normally with Pin 11 open-circuit,

and produces a regulated output voltage when a valid

applied to pin 11, the converter output will be turned off.

Figure 2-1 shows an application schematic, which details

the typical use of the Remote On/Off function. Note the

internal pull-up, and must be controlled with an open-

collector or open-drain device (See notes 2 & 3). Table 2-1

gives the input requirements.

When placed in the “Off” state, the standby current drawn

from the input source is typically reduced to less than 1 mA.

Parameter

Min

Typ

Max

Disable

–0.1 V

—

1 V

Enable

5 V 3

—

Open-Circuit 2

Vo/c [Open-Circuit]

—

—

10 V

Iin [pin 11 at –Vin]

—

–200 µA

—

Notes:

ground reference. All voltages specified are with respect

2. Use an open-collector device (preferably a discrete

transistor) for the Remote On/Off input. Do not connect

a pull-up resistor directly to pin 11.

3. The Remote On/Off pin may be controlled with devices that

have a totem-pole output providing that a blocking

diode is used. The blocking diode is required to prevent

current from being injected into On/Off control pin.

Note: For TTL devices a pull-up may be required on the

cathode side of the blocking diode. This is to guarantee a

minimum enable voltage at pin 11 (See Figure 2-1).

4. The PT4310 converters incorporate an “Under-Voltage

Lockout” (UVLO). The UVLO will keep the module

off when the input voltage to the converter is low,

regardless of the state of the Remote On/Off control.

Table 2-2 gives the UVLO input voltage thresholds.

Figure 2-1

Turn-On Time:

applies a low-voltage to pin 11 and disables the converter

verter to power up and produce a regulated output voltage

within 50 ms. Although the rise-time of the output is short

(<1ms), the delay time will vary depending upon the input

voltage and the module’s internal timing. Figure 2-2

shows response of the +5-V output from the PT4311

waveform was measured with a 48 Vdc input voltage,

and 0.25-Adc resistive load at both the positive and

negative outputs.

Figure 2-2

R1

10k

Q1

BSS138

+V

o

-V

o

+V

in

-V

in

Vdd

1 =OFF

Note 1

U1a

Note 1

Note 1

D1

PT4310

+Vin

-Vin

±Vo

Adjust

11

17

18

1

2

3

COM

Remote

On/Off

12

Vo

Vo

0

5

10

15

20

25

30

time (milli-secs)

delay time

Series

UVLO Threshold

PT4310

38 – 75 V

36 ±2 V