9.3.1 On/Off Control

The ON pin controls the state of the switch. Asserting ON high enables the switch. 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.

9.3.2 Output Pull-Down

The output pull-down is active when the user is turning off the main pass FET. The pull-down discharges the output rail to approximately 10% of the rail, and then the output pull-down is automatically disconnected to optimize the shutdown current.

9.3.3 Under-Voltage Lockout

The under-voltage lockout turns-off the switch if the input voltage drops below the under-voltage lockout threshold. During under-voltage lockout (UVLO), if the voltage level at V_OUT exceeds the voltage level at V_IN by the Reverse Current Voltage Threshold (V_RVP), the body diode will be disengaged to prevent any current flow to V_IN. With the ON pin active the input voltage rising above the under-voltage lockout threshold will cause a controlled turn-on of the switch which limits current over-shoots.

9.3.4 Reverse Current Protection

In a scenario where V_OUT is greater than V_IN, there is potential for reverse current through the pass FET or the body diode. The TPS22929D monitors V_IN and V_OUT voltage levels. When the reverse current voltage threshold (V_RVP) is exceeded, the switch is disabled (within 10 µs typ). Additionally, the body diode is disengaged so as to prevent any reverse current flow to V_IN. The FET, and the output (V_OUT), will resume normal operation when the reverse voltage scenario is no longer present.

Use the following formula to calculate the amount of reverse current required to activate the protection circuit for a particular application:

Where,

I_RC is the amount of reverse current,

R_ON(VIN) is the on-resistance as determined by the input voltage.

Table 1. Function Table