Abstract: A frequency/voltage conversion circuit is provided with a detection circuit for determining when the input frequency rises above a predetermined level which threatens to inhibit operation of flip-flop devices in the circuit. In response to the detection, a capacitor of a first charging/discharging circuit is forcibly charged to a value above a predetermined level.

Abstract: A driving circuit for a two-phase brushless motor which includes a magnetized rotor, first and second magnetically sensitive elements disposed adjacent the rotor, and a pair of driving coils. The magnetically sensitive elements are coupled in series with one another and a bias voltage is applied thereto. First and second differential pairs of transistors receive inputs from the first and second magnetically sensitive elements, respectively, and the first and second differential pairs are coupled in series with one another and a constant current is applied thereto. Current mirror circuits produce currents in proportion to the currents flowing in the first and second differential pairs and output drivers energize the coils of the motor in response to outputs of the current mirror circuits.