Operating circuit for operating light-emitting module at power source, has protective circuit that is switched only into conductive state by control signal, if applied voltage on current limiting circuit exceeds threshold level

摘要

The operating circuit (10) has a protective circuit (14) that is switched between a conductive state and a closing state. A control signal is applied to a control input (23) of protective circuit, such that the voltage is applied against a current limiting circuit (21). The protective circuit is switched only into conductive state by control signal, if the applied voltage on current limiting circuit exceeds a threshold level. A first transistor of limiting circuit is connected in series to a light-emitting module (20) and a resistor is connected in series to first transistor.