PTH05010W_15 Datasheet, PDF (9/19 Pages) Texas Instruments – 15-A, 5-V Input Non-Isolated Wide-Output Adjust Power Module

Application Notes
PTH Series of Wide-Output Adjust
Power Modules (3.3/5-V Input)
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 set-
point voltage. Figure 3-2 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, with Auto-Track 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.
Over-Current Protection
For protection against load faults, all modules incorporate
output over-current protection. Applying a load that
exceeds the regulator’s over-current threshold will cause
the regulated output to shut down. Following shutdown
a module will periodically attempt to recover by initiating
a soft-start power-up. This is described as a “hiccup” mode
of operation, whereby the module continues in a cycle of
successive shutdown and power up until the load fault is
removed. During this period, the average current flowing
into the fault is significantly reduced. Once the fault is
removed, the module automatically recovers and returns
to normal operation.
Over-Temperature Protection
The PTHxx020 and PTHxx030 series of products have
over-temperature protection. These products have an
on-board temperature sensor that protects the module’s
internal circuitry against excessively high temperatures.
A rise in the internal temperature may be the result of a
drop in airflow, or a high ambient temperature. If the
internal temperature exceeds the OTP threshold, the
module’s Inhibit control is automatically pulled low. This
turns the output off. The output voltage will drop as the
external output capacitors are discharged by the load
circuit. The recovery is automatic, and begins with a
soft-start power up. It occurs when the the sensed tem-
perature decreases by about 10 °C below the trip point.
Note: The over-temperature protection is a last resort mecha-
nism to prevent thermal stress to the regulator. Operation at
or close to the thermal shutdown temperature is not recom-
mended and will reduce the long-term reliability of the module.
Always operate the regulator within the specified Safe Operating
Area (SOA) limits for the worst-case conditions of ambient
temperature and airflow.
Output On/Off Inhibit
For applications requiring output voltage on/off control,
each series of the PTH family incorporates an output
Inhibit control pin. The inhibit feature can be used wher-
ever there is a requirement for the output voltage from
the regulator to be turned off.
The power modules function normally when the Inhibit
pin is left open-circuit, providing a regulated output
whenever a valid source voltage is connected to V_in with
respect to GND.
Figure 3-3 shows the typical application of the inhibit
function. Note the discrete transistor (Q₁). The Inhibit
control has its own internal pull-up to V_in potential. The
input is not compatible with TTL logic devices. An open-
collector (or open-drain) discrete transistor is recommended
for control.
Figure 3–3
10 9
8
V_o Sense
5
V_IN
2
PTH05020W
6
V_OUT
C_IN
1,000 µF
1 =Inhibit
GND
3
Q₁
BSS138
17
4
R_SET
C_OUT
L
O
330 µF
A
D
GND
Turning Q₁ on applies a low voltage to the Inhibit control
and disables the output of the module. If Q₁ is then turned
off, the module will execute a soft-start power-up. A
regulated output voltage is produced within 20 msec.
Figure 3-4 shows the typical rise in both the output volt-
age and input current, following the turn-off of Q₁. The
turn off of Q₁ corresponds to the rise in the waveform,
Q₁ V_ds. The waveforms were measured with a 5-A load.
Figure 3–4
HORIZ SCALE: 10ms/Div
Vo (2V/Div)
Iin (2A/Div)
Q1Vds (5V/Div)
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