Datasheet

TPS22921, TPS22922, TPS22922B
www.ti.com SLVS749B –NOVEMBER 2008–REVISED MAY 2013
APPLICATION INFORMATION
ON/OFF Control
The ON pin controls the state of the switch. Activating ON continuously holds the switch in the on state. ON is
active high and has a low threshold making it capable of interfacing with low voltage signals. The ON pin is
compatible with standard GPIO logic threshold. It can be used with any microcontroller with 1.2-V, 1.8-V, 2.5-V or
3.3-V GPIOs.
Input Capacitor
To limit the voltage drop on the input supply caused by transient inrush currents when the switch turns on into a
discharged load capacitor or short-circuit, a capacitor must be placed between V
IN
and GND. A 1-μF ceramic
capacitor, C
IN
, placed close to the pins is usually sufficient. Higher values of C
IN
can be used to further reduce
the voltage drop during higher current application. When switching a heavy load, it is recommended to have an
input capacitor about 10 or more times higher than the output capacitor in order to avoid any supply drop.
Output Capacitor
Due to the integral body diode in the PMOS switch, a C
IN
greater than C
L
is highly recommended. A C
L
greater
than C
IN
can cause V
OUT
to exceed V
IN
when the system supply is removed. This could result in current flow
through the body diode from V
OUT
to V
IN
.
Board Layout
For best performance, all traces should be as short as possible. To be most effective, the input and output
capacitors should be placed close to the device to minimize the effects that parasitic trace inductances may have
on normal and short-circuit operation. Using wide traces for V
IN
, V
OUT
, and GND will help minimize the parasitic
electrical effects along with minimizing the case to ambient thermal impedance.
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Product Folder Links: TPS22921 TPS22922 TPS22922B