Datasheet

V (1V/Div)
O
V (1V/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
0.1W,1%
SET
W
PTH05020W
7
1
0
4
5
62
3
9
Track
V
I
V
O
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, V
in
(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 Submit Documentation Feedback Copyright © 2005–2010, Texas Instruments Incorporated
Product Folder Link(s): PTH04040W