Datasheet

APPLICATION INFORMATION
ON/OFF Control
Input Capacitor
Output Capacitor
Board Layout
TPS22906
SLVS921 – MARCH 2009 ................................................................................................................................................................................................... www.ti.com
The ON pin controls the state of the switch. Activating ON continuously holds the switch in the on state so long
as there is no fault. ON is active HI 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.
To limit the voltage drop on the input supply caused by transient in-rush currents when the switch turns on into a
discharged load capacitor or short-circuit, a capacitor needs to be placed between V
IN
and GND. A 1- µ F ceramic
capacitor, C
IN
, place close to the pins is usually sufficient. Higher values of C
IN
can be use to further reduce the
voltage drop during high current application. When switching heavy loads, it is recommended to have an input
capacitor approximately 10 times higher than the output capacitor to avoid excessive voltage drop.
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
.
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 helps minimize the parasitic
electrical effects along with minimizing the case to ambient thermal impedance.
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