Patent ID: 8040647

Claim:
A method for protecting a reverse battery protected device under loss of power, the reverse battery protected device including a switched inductive load, a substrate switch coupled in parallel with the switched inductive load and a voltage source coupled in parallel with the substrate switch, the substrate switch having a semiconductor substrate and the voltage source having a voltage Vs, the method comprising: under reverse polarity, biasing the substrate of the substrate switch at a negative voltage −Vs, the voltage Vs of the voltage source being less than an absolute value of a first substrate clamping voltage of the substrate switch so that the substrate switch is non-conducting under reverse polarity; and under loss of power, clamping the substrate of the substrate switch to a second substrate clamping voltage, an absolute value of the second substrate clamping voltage being less than the absolute value of the first substrate clamping voltage for distributing power dissipation between the substrate switch and the switched inductive load.