SLVSE17A May 2019 – April 2020 TPS1HB16-Q1
In the reverse battery condition, the switch will automatically be enabled regardless of the state of EN to prevent excess power dissipation inside the MOSFET body diode. In many applications (for example, resistive loads), the full load current may be present during reverse battery. In order to activate the automatic switch on feature, SEL must have a path to ground from either from the MCU or it needs to be tied to ground if unused.
There are two options for blocking reverse current in the system. The first option is to place a blocking device (FET or diode) in series with the battery supply, blocking all current paths. The second option is to place a blocking diode in series with the GND node of the high-side switch. This method will protect the controller portion of the switch (path 2), but it will not prevent current from flowing through the load (path 3). The diode used for the second option may be shared amongst multiple high-side switches.
Path 1 shown in Figure 35 is blocked inside of the device.
For more information on reverse battery protection, refer to TI's Reverse Battery Protection for High Side Switches application note.