Patent ID: 8148969

Claim:
A circuit arrangement for the regulation of a fan motor current (I L ) through a load (R L ), the arrangement comprising: a resistance (R S ), through which a fan motor load current (I L ) flows and across which a voltage (V S ) drops, which serves as a control variable (X) for the regulation of the fan motor load current (I L ); a tapping point (P) for a reference voltage (V ref ), which serves as a command variable (W) for the regulation of the fan motor load current (I L ); a differential amplifier (OV) for the amplification of the control deviation (W - X) between command variable (W) and control variable (X), said differential amplifier having a first and a second base-coupled transistor (Q 1 , Q 2 ); and a transistor (Q 4 ), a collector resistance (R 2 ) and an emitter resistance (R 6 ) for the regulation of the fan motor load current (I L ) as a function of a load voltage (V L ), and including a device for the adjustment of a constant ratio of the collector quiescent currents through the base-coupled transistors (Q 1 , Q 2 ), which is formed by two resistances (R 1 , R 3 ), said device being adapted to reduce a maximum load current through the fan motor with increasing temperature wherein the series connection of the base-emitter section of the fourth transistor (Q 4 ) and the emitter resistance (R 6 ) is arranged parallel to the load (R L ), and wherein the tapping point (P) for the reference voltage is arranged between the collector resistance (R 2 ) and the transistor (Q 4 ).