The MC3399 is a HighSide Switch designed to drive loads from the positive side of the power supply. The output is controlled by a TTL compatible input Enable pin. In the "on" state, the device exhibits very low saturation voltages for load currents in excess of 750 mA. The device isolates the load from positive or negative going high voltage transients by abruptly "opening" thus protecting the load from the transient voltage for the duration of the transient. The device automatically reestablishes its original operating state following the transient condition. The MC3399 is fabricated on a power BIMOS process which combines the best features of Bipolar and MOS technologies. The mixed technology provides higher gain PNP output devices and results in Power Integrated Circuits having substantially reduced quiescent currents. The device operates over a wide power supply voltage range and can withstand voltage transients (positive or negative) of 100 V. A rugged PNP output stage along with active clamp circuitry, output current limit and thermal shutdown permit the driving of all types of loads, including inductive. The MC3399 is offered in 5lead TO220 and 16lead SOIC plastic packages to facilitate either "thruhole" or surface mount use. In addition, it is specified over a wide ambient operating temperature of 40C to +125C and is ideally suited for industrial and automotive applications where harsh environments exist.