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Using the Remote On/Off Function on the PTQB425080 Series of DC/DC Converters

Negative Output Enable (N Option)

Positive Output Enable (P Option)

PTQB425080

SLTS269A – DECEMBER 2006 – REVISED JANUARY 2007

For applications requiring output voltage On/Off control, the PTQB425080 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

Disable

2.4 V

20 V

Enable

–0.2 V

0.8 V

Open-Circuit

9 V

15 V

–0.75 mA

For those models with the positive enable option, leaving pin 2 open circuit, (or driving it to an equivalent logic

high voltage), will enable the converter output. This allows the module to produce an output voltage whenever a

converter output is disabled. Table 2 gives the input requirements of pin 2 for modules with the PEN option.

Table 2. On/Off Control Requirements

for Positive Enable

PARAMETER

MIN

TYP

MAX

Enable

4.5 V

20 V

Disable

–0.2 V

0.8 V

Open-Circuit

5 V

7 V

–0.5 mA

Notes:

2. An open-collector device (preferably a discrete transistor) is recommended. A pull-up resistor is not

required. If one is added the pull-up voltage should not exceed 20 V.

of 20 V. Exceeding this voltage will overstress, and possibly damage, the converter.

3. The Remote On/Off pin may be controlled with devices that have a totem-pole output. This is provided the

used, a pull-up resistor may be required to the logic supply voltage.

4. The converter incorporates an undervoltage lockout (UVLO). The UVLO keeps the converter off until the

input voltage is close to the minimum specified operating voltage. This is regardless of the state of the

Remote On/Off control. Consult the product specification for the UVLO input voltage thresholds.

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