Application Notes

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Output On/Off Inhibit

For applications requiring output voltage on/off control,

the PTH03000W & PTH05000W power modules in-

corporate an output on/off Inhibit control (pin 3). The

inhibit feature can be used wherever there is a require-

ment for the output voltage from the regulator to be

turned off.

The power module functions normally when the Inhibit

pin is left open-circuit, providing a regulated output

respect to GND.

Figure 3-2 shows the typical application of the inhibit

open-collector or open-drain device is recommended to

control this input.

turned off, the module will execute a soft-start power-up

sequence. A regulated output voltage is produced within

20 msec. Figure 3-3 shows the typical rise in the out-

waveforms were measured with a 5-A resistive load.

Figure 3-2

Figure 3-3

Power-Up Characteristics

When configured per their standard application, the

PTH03000 and PTH05000 series of power modules will

produce a regulated output voltage following the appli-

cation of a valid input source voltage. During power up,

internal soft-start circuitry slows the rate that the output

voltage rises, thereby limiting the amount of in-rush

current that can be drawn from the input source. The

soft-start circuitry introduces a short time delay (typi-

cally 10 ms) into the power-up characteristic. This is

from the point that a valid input source is recognized.

Figure 3-1 shows the power-up waveforms for a PTH05000W

(5-V input), with the output voltage set point adjusted for a

2-V output. The waveforms were measured with a 5-A

resistive load. The initial rise in input current when the

input voltage first starts to rise is the charge current drawn

by the input capacitors.

Figure 3-1

Current Limit Protection

The PTHxx000W modules protect against load faults

with a continuous current limit characteristic. Under a

load fault condition the output current cannot exceed

the current limit value. Attempting to draw current that

exceeds the current limit value causes the output voltage

to be progressively reduced. Current is continuously

supplied to the fault until it is removed. Upon removal of

the fault, the output voltage will promptly recover.

Thermal Shutdown

Thermal shutdown protects the module’s internal circuitry

against excessively high temperatures. A rise in tempera-

ture may be the result of a drop in airflow, a high ambient

temperature, or a sustained current limit condition. If

the junction temperature of the internal components

exceed 150 °C, the module will shutdown. This reduces

the output voltage to zero. The module will start up

automatically, by initiating a soft-start power up when

the sensed temperature decreases 10 °C below the thermal

shutdown trip point.

PTH03000 & PTH05000 Series

PTH05000W

V

1

4

5

2

3

C

IN

330 µF

(Required)

C

OUT

100 µF

(Optional)

Inhibit

GND

V

4k87

0.1 W, 1 %

V

GND

Inhibit

V

IN

V

O

L

O

A

D

GND

Q

1

BSS138

Vo (1 V/Div)

Q1 Vgs

(10 V/Div)

HORIZ SCALE: 5 ms/Div

Vin (2 V/Div)

Vo (1 V/Div)

Iin (2 A/Div)

HORIZ SCALE: 5 ms/Div