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Differential Remote Sense

Using the Remote On/Off Function on the PTQA4300xx Series of DC/DC Converters

Negative Output Enable (NEN)

PTQA430025, PTQA430033

SLTS261 – MAY 2006

The remote sense pins allows the converter to precisely regulate the DC output voltage at a remote location.

internal 10-

Ω resistor between each sense pin and its corresponding output prevents an excessive rise in the

output voltage. For practical reasons, the amount of IR voltage compensation should be limited to 0.5 V

maximum.

The remote sense feature is designed to compensate for limited amounts of IR voltage drop. It is not intended to

compensate for the forward drop of a non-linear or frequency dependent components that may be placed in

series with the converter output. Examples of such components include OR-ing diodes, filter inductors, ferrite

beads, and fuses. Enclosing these components with the remote sense connections effectively places them

inside the regulation control loop, which can affect the stability of the regulator.

For applications requiring output voltage On/Off control, the PTQA4300xx series of DC/DC converters

incorporate a Remote On/Off control (pin 2). This feature can be used to switch the module off without removing

the applied input source voltage. When placed in the Off state, the standby current drawn from the input source

is typically reduced to 3 mA.

Models using the negative enable option, the Remote On/Off (pin 2) control must be driven to a logic low voltage

3), or driving it low with an external control signal. Table 1 shows the input requirements of pin 2 for those

modules with the NEN option.

Table 1. On/Off Control Requirements

for Negative Enable

PARAMETER

MIN

TYP

MAX

Enable

2.4 V

20 V

Disable

–0.2 V

0.8 V

Open-Circuit

9 V

15 V

–0.75 mA

9

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