Datasheet

Output On/Off Inhibit
2
1
3
V
I
Inhibit
GND
PTR08100W
C
I
GND
V
I
UDG-07117
1=Inhibit
V
INH
(1 V/div)
V
O
(2 V/div)
I
I
(2 A/div)
t − Time − 4 ms/div
PTR08100W
SLTS284E – AUGUST 2007 – REVISED APRIL 2009 ....................................................................................................................................................... www.ti.com
For applications requiring output voltage on/off control, the PTR08100W power module incorporates an output
on/off Inhibit control (pin 1). The inhibit feature can be used wherever there is a requirement 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
whenever a valid source voltage is connected to Vin with respect to GND.
Figure 14 shows the typical application of the inhibit function. Note the discrete transistor (Q1). The Inhibit control
has its own internal pullup to V
I
potential. An open-collector or open-drain device is recommended to control this
input.
Turning Q1 on applies a low voltage to the Inhibit control pin and disables the output of the module. If Q1 is then
turned off, the module will execute a soft-start power-up sequence. A regulated output voltage is produced within
20 msec. Figure 15 shows the typical rise in the output voltage, following the turn off of Q1. The turn off of Q1
corresponds to the rise in the waveform, V
INH
. The waveforms were measured with a 6-A constant current load.
Figure 14. On/Off Inhibit Control Circuit
Figure 15. Power Up Response From Inhibit Control
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