Over-current protection for DC motor pulse width modulation regulator

摘要

The over-current protection is supplied with a control voltage by using the internal resistance of the power MOSFET (11) connected in series with the DC motor (17) as the measuring resistance for over-current detection, with the power MOSFET blocked when an over-current is indicated. An auxiliary transistor (15) is coupled at its base to the control electrode of the power MOSFET, its collector/emitter path connected between the output of the power MOSFET and the control electrode of thyristor (14) via a pair of series resistors (20, 21) with the junction between the latter earthed via a capacitor (22).