V

(1V/Div)

O

V (1V/Div)

I

I (5 A/Div)

I

t-Time=5 msec/Div

5 V

C

330 F

O

m

C

1,000 F

I

m

GND

GND

3.3 V

R

698

0.1W,1%

SET

W

PTH05020W

7

10

4

5

6

2

3

9

Track

VI

VO

GND

Inhibit

1

Up

Dn

Sense

Adjust

8

PTH04040W

SLTS238C – SEPTEMBER 2005 – REVISED JUNE 2010

www.ti.com

FEATURES OF THE PTH FAMILY OF NONISOLATED WIDE OUTPUT ADJUST POWER

MODULES

POLA™ COMPATIBILITY

The PTH/PTV family of nonisolated, wide-output adjustable power modules are optimized for applications that

require a flexible, high performance module that is small in size. Each of these products are POLA™ compatible.

POLA-compatible products are produced by a number of manufacturers, and offer customers advanced,

nonisolated modules with the same footprint and form factor. POLA parts are also assured to be interoperable,

thereby providing customers with second-source availability.

Many of the POLA-compatible parts include a feature called Auto-Track™. Auto-Track was specifically designed

to simplify the task of sequencing the supply voltages in a power system. This and other features are described

the following sections.

SOFT-START POWER UP

The Auto-Track feature allows the power-up of multiple PTH modules to be directly controlled from the Track pin.

However in a stand-alone configuration, or when the Auto-Track feature is not being used, the Track pin should

be directly connected to the input voltage, Vin (see Figure 11).

Figure 11. Power-Up Application Circuit

Figure 12. Power-Up Waveforms

When the Track pin is connected to the input voltage the Auto-Track function is permanently disengaged. This

allows the module to power up entirely under the control of its internal soft-start circuitry. When power up is

under soft-start control, the output voltage rises to the set-point at a quicker and more linear rate.

From the moment a valid input voltage is applied, the soft-start control introduces a short time delay (typically

5 ms–10 ms) before allowing the output voltage to rise. The output then progressively rises to the module’s

setpoint voltage. Figure 12 shows the soft-start power-up characteristic of the 22-A output product

(PTH05020W), operating from a 5-V input bus and configured for a 3.3-V output. The waveforms were measured

with a 5-A resistive load and the Auto-Track feature disabled. The initial rise in input current when the input

voltage first starts to rise is the charge current drawn by the input capacitors. Power-up is complete within 15 ms.

14

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