Reverse current occurs in two conditions: short to
power and reverse polarity.
- When a short to the input occurs, there is only
reverse current through the body diode. IR1 specifies the limit of the reverse
current.
- In a reverse-polarity condition, there are
reverse currents through the body diode and the device GND pin. IR2 specifies
the limit of the reverse current. The GND pin maximum current is specified in the Absolute Maximum
Ratings.
To protect the device, TI recommends two types of external circuitry.
- Adding a blocking diode. Both the IC and load are
protected when in reverse polarity.
- Adding a GND network. The reverse current
through the device GND is blocked. The reverse current through the FET is limited by the
load itself. TI recommends a resistor in parallel with the diode as a GND network. The
recommended selection are 1-kΩ resistor in parallel with a >100-mA diode. If multiple
high-side switches are used, the resistor and diode can be shared among devices. The
reverse current protection diode in the GND network forward voltage should be less than
0.6 V in any circumstances. In addition a minimum resistance of 4.7 kΩ is recommended on
the I/O pins.