CURRENT MONITORING CIRCUIT

摘要

PROBLEM TO BE SOLVED: To reduce variation of a threshold current in current monitoring.SOLUTION: An OCP circuit 14A includes: transistors Q1 and Q2 forming a current mirror; constant current supply circuits (M10 to M12) supplying a constant current to respective collectors of the transistors Q1 and Q2; a transistor M0 in which a driving current I2 of a motor flows; a series circuit of transistors M1 and M2 which is connected in parallel to the transistor M0 and in which a sense current I1 corresponding to the driving current I2 flows; a transistor M3 connected in series to the transistor Q1; and a monitoring output circuit 50 which outputs an overcurrent protection signal Socp corresponding to a current flowing in the transistor Q2. The transistors M2 and M3 are provided in series between respective emitters of the transistors Q1 and Q2.