As discussed in the section regarding Reverse supply, D_GND may be used to prevent excessive reverse current from flowing into the device during a reverse supply event. Additionally, R_GND is placed in parallel with D_GND if the switch is used to drive an inductive load. The ground protection network (D_GND and R_GND) may be shared amongst multiple high-side switches.

A minimum value for R_GND may be calculated by using the absolute maximum rating for I_GND. During the reverse supply condition, I_GND = V_BB / R_GND:

• Set V_BB = –13.5 V
• Set I_GND = –50 mA (absolute maximum rating)

  R_GND ≥ –13.5 V / –50 mA = 270 Ω

In this example, it is found that R_GND must be at least 270 Ω. It is also necessary to consider the power dissipation in R_GND during the reverse supply event:

P_RGND = (13.5 V)² / 270 Ω = 0.675 W

In practice, R_GND may not be rated for such a high power. In this case, a larger resistor value should be selected.