Power transistor switch status monitoring circuit

摘要

The monitoring circuit detects the voltage across the power transistor (1) and the voltage across the supplied load (3). The detected voltages are fed to respective voltage comparators (7,8), the first comparator (7) activated by the power transistor input signal (UIN) when the transistor (1) is conductive and the second comparator (8) activated when the transistor (1) is blocked. The outputs from both comparators (7,8) are combined to obtain the status signal (Ustat). Pref. the activation of the 2 comparators (7,8) is pref. effected via AND gates (10,11) respectively controlled directly by the power transistor input signal (UIN) and via an inverter (9).