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PTH12060W

1

10

4

5

6

2

3

1 = Inhibit

GND

9

V Sense

O

8

Q1

BSS138

7

GND

L

O

A

D

R

2k

0.1 W, 1%

SET

W

C

330 F

O

m

C

560 F

I

m

V

I

V

O

V

(2 V/Div)

O

I (2 A/Div)

I

Q1Vds (5 V/Div)

t - Time = 10 s/Div

m

Auto-Track™ Function

PTH12060W/L

SLTS217D–MAY 2003–REVISED OCTOBER 2005

Figure 12. Inhibit Control Circuit

Turning on Q1 applies a low voltage to the Inhibit control pin and disables the output of the module. If Q1 is then

turned off, the module executes a soft-start power-up sequence. A regulated output voltage is produced within 25

turn off of Q1 corresponds to the rise in the waveform, Q1 Vds. The waveforms were measured with a 5-A

constant current load.

Figure 13. Power-Up from Inhibit Control

The Auto-Track function is unique to the PTH/PTV family, and is available with all POLA products. Auto-Track

was designed to simplify the amount of circuitry required to make the output voltage from each module power up

and power down in sequence. The sequencing of two or more supply voltages during power up is a common

requirement for complex mixed-signal applications that use dual-voltage VLSI ICs such as the TMS320™ DSP

family, microprocessors, and ASICs.

How Auto-Track™ Works

This control range is limited to between 0 V and the module set-point voltage. Once the track-pin voltage is

of a 2.5-V regulator is at 1 V, the regulated output is 1 V. If the voltage at the Track pin rises to 3 V, the regulated

output does not go higher than 2.5 V.

When under Auto-Track control, the regulated output from the module follows the voltage at its Track pin on a

volt-for-volt basis. By connecting the Track pin of a number of these modules together, the output voltages follow

a common signal during power up and power down. The control signal can be an externally generated master

incorporates an internal RC-charge circuit. This operates off the module input voltage to produce a suitable rising

waveform at power up.

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