ATH10K12 Datasheet, PDF (8/13 Pages) Astec America, Inc – 10-A, 12-V Input Non-Isolated Wide-Output Adjust Power Module

Application Notes
ATH Series of Wide-Output Adjust
Power Modules (12-V Input)
Output On/Off Inhibit
For applications requiring output voltage on/off control,
each series of the ATH 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 3-2 shows the typical application of the inhibit
function. Note the discrete transistor (Q₁). The Inhibit
input has its own internal pull-up to V_in potential (12 V).
The input is not compatible with TTL logic devices. An
open-collector (or open-drain) discrete transistor is rec-
ommended for control.
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 3-3 shows the typical rise in both the
output voltage 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 constant current load.
Figure 3-2
V_o Sense
10 9
85
V_IN
2 _{PATTHH11200K6120W} 6
V_OUT
C_IN
560 µF
1 =Inhibit
GND
31 7
Q₁
BSS138
4
R_SET
2.0kΩ
C_OUT
330 µF
L
O
A
1%
D
0.1 W
GND
Figure 3-3
Q1Vds (5 V/Div)
Vo (2 V/Div)
Remote Sense
The ATH10 (10A), ATH12/15 (12/15A), ATH18/22 (18/
22A), and ATH26/30 (26/30A) products incorporate an
output voltage sense pin, V_o Sense. The V_o Sense pin should
be connected to V_out at the load circuit (see data sheet stan-
dard application). A remote sense improves the load
regulation performance of the module by allowing it to
compensate for any ‘IR’ voltage drop between itself and the
load. An IR drop is caused by the high output current
flowing through the small amount of pin and trace resis-
tance. Use of the remote sense is optional. If not used,
the V_o Sense pin can be left open-circuit. An internal
low-value resistor (15-Ω or less) is connected between
the V_o Sense and V_out. This ensures the output voltage re-
mains in regulation.
With the sense pin connected, the difference between
the voltage measured directly between the V_out and GND
pins, and that measured from V_o Sense to GND, is the
amount of IR drop being compensated by the regulator.
This should be limited to a maximum of 0.3 V.
Note: The remote sense feature is not designed to compensate
for the forward drop of non-linear or frequency dependent
components that may be placed in series with the converter
output. Examples include OR-ing diodes, filter inductors,
ferrite beads, and fuses. When these components are enclosed
by the remote sense connection they are effectively placed
inside the regulation control loop, which can adversely affect
the stability of the regulator.
Over-Temperature Protection (OTP)
The ATH18/22 (18/22A) and ATH26/30 (26/30A) series of
products have over-temperature protection. These prod-
ucts 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 tem-
perature. 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 be-
gins with a soft-start power up. It occurs when the the
sensed temperature 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.
Iin (2 A/Div)
HORIZ SCALE: 10 ms/Div
North America (USA): 1-888-41-ASTEC
Europe (UK): 44(1384)842-211
Asia (HK): 852-2437-9662