SLVSE17A May 2019 – April 2020 TPS1HB16-Q1
As discussed in the Reverse Battery section, DGND may be used to prevent excessive reverse current from flowing into the device during a reverse battery event. Additionally, RGND is placed in parallel with DGND if the switch is used to drive an inductive load. The ground protection network (DGND and RGND) may be shared amongst multiple high-side switches.
A minimum value for RGND may be calculated by using the absolute maximum rating for IGND. During the reverse battery condition, IGND = VBB / RGND:
In this example, it is found that RGND must be at least 270 Ω. It is also necessary to consider the power dissipation in RGND during the reverse battery event:
PRGND = (13.5 V)2 / 270 Ω = 0.675 W
In practice, RGND may not be rated for such a high power. In this case, a larger resistor value should be selected.