A Smart IGBT Gate Driver IC With Temperature Compensated Collector Current Sensing

Conventional insulated gate bipolar transistor (IGBT) current sensing and protection techniques usually employ discrete sensors, such as lossy shunt resistors, and may involve accessing the high-voltage collector load of the IGBT. This would normally present difficulties for integration. This paper presents an IGBT gate driver I-C with a collector current sensing circuit and an on-chip CPU for local data processing. This I-C is prototyped using a TSMC 0.18 mu m 40 V BCD Gen-2 process. The collector current sensing technique is based on the unique Miller plateau relationship between the gate current and collector current (I-C and I-G) for a particular gate resistance (R-G). It allows a cycleby- cycle measurement of I-C during both turn-ON and turn-OFF transients without any extra discrete components. The temperature variation is compensated internally by the on-chip CPU using polynomial curve fitting. This technique only monitors the lowvoltage signal at the gate terminal, without the need to handle any high-voltage signal on the collector/load side. Measurements using a double pulse test setup show an accuracy of +/- 0.5 A over the current ranges of 1-30 A for turn-ON and 1-50 A for turn-OFF from 25 to 75 degrees C.