A 70 m/spl Omega/ intelligent high side switch with full diagnostics

摘要

A new, smart power switch for industrial, automotive, and computer applications developed in BCD (Bipolar, CMOS, DMOS) technology is described. It consists of an on-chip 70 m/spl Omega/ power DMOS transistor connected in high side configuration and its driver makes the device virtually indestructible and suitable to drive any kind of load with an output current of 2.5 A. If the load is inductive, an internal voltage clamp allows fast demagnetization down to 55 V below the supply voltage. The device includes novel structures for the driver, the fully integrated charge pump circuit, and its oscillator. These circuits have specifically been designed to reduce electromagnetic interference (EMI) thanks to an accurate control of the output voltage slope and the reduction of the output voltage ripple caused by the charge pump itself. An innovative open load circuit allows the detection of the open load condition with high precision (3 mA /spl plusmn/10% within the temperature range from -25 to 150/spl deg/C and including process spreads). Furthermore, the device protects the load from ground disconnection and is compatible with the new IEC standards concerning burst and surge tests. The quiescent current has also been reduced to 600 /spl mu/A. Diagnostics for CPU feedback is externally available from the chip by two dedicated pins when the following fault conditions occur: open load, overload and short circuit to ground or to the supply voltage, overtemperature, and undervoltage supply.