Inexpensive power switch includes submicrosecond circuit breaker

摘要

The circuit in Figure 1 lets you switch high-voltage power to a grounded load with a low-volt-age control signal. The circuit also functions as a submicrosecond circuit breaker that protects the power source against load faults. Power switches to the load when you apply a logic-level signal to the output control terminal. When the signal is lower than 0.7V, transistor Q_3 is off and the gate of P-channel MOSFET Q_4 pulls up to the positive supply through R_6, thus holding Q_4 off. During this off condition, the circuit's quiescent-current drainrnis 0A.