Circuit arrangement for current overload and short circuit protection in MOS integrated circuits monitors both load current and voltage across transistor controlling load

摘要

A power transistor (T2) controls the current in a load (RL) which has in series with it a shunt resistor (R1). The shunt voltage (US) is fed to a current monitoring circuit (20) which controls the power transistor through a control transistor (T1) so that the load current cannot rise above a first threshold. A second monitoring circuit (40,T3,T4) controls the first if the voltage drop across the power transistor and the shunt rises above a set voltage so that the load current is limited to a value below the first threshold.