The MC3392 is a low side protected switch designed for use in harsh automotive applications which require the capability of handling high voltages attributed to load and field dump transients, in addition to reverse and double battery conditions. The three terminal TO220 is intended to replace power Darlington transistors in new and existing switching applications when taking into account the CMOS input levels required by the MC3392. It offers improved functionality and ruggedness over power Darlingtons while retaining the same package and pin configuration, and can be used as a replacement in many applications using the industry standard TIP100/101 NPN power Darlington transistor. The fiveterminal TO220 has the added feature of having a Fault output (active low) which will indicate the existence of an over temperature, overvoltage or current limit condition, including an output short to ground. When driving a moderate load, the MC3392 performs as an extremely high gain, low saturation Darlington transistor having CMOS input levels. The primary advantage of the MC3392 over a Darlington transistor is the additional protection afforded the device and load when driving difficult or faulty loads. This device incorporates unique internal current limit and thermal protection circuitry to safeguard itself and the associated load from catastrophic failure.