MOS power switching circuit IC with short circuit protection - has current limiter between source of MOS power transistor and base of bipolar transistor

摘要

The power MOS switching device consists of output transistor (101), with associated MOS device (102), current sense resistor (104) and bipolar transistor (103). The current-voltage characteristic is: Id = KVds (Vin - B Rin / Rb x Vds + B Rin / Rd x Vf - Vt). For normal operation, as the drain voltage increases, an increasing current in (102) causes (103) to turn on, limiting the gate drive voltage (G). In the saturated state for (101) the drain voltage is proportional to current. When no gate voltage is applied, both (102) and (101) are cut off, switching off the leakage current Id. ADVANTAGE - Prevents damage due to overheating when load is short-circuited.