公开(公告)号：JPH11127591A

公开(公告)日：1999-05-11

申请号：JP18602898

申请日：1998-07-01

Applicant: ST MICROELECTRON INC

Inventor： MENEGOLI PAOLO ,  COLLI GIANLUCA

IPC: G05F3/26 ,  G11B19/20 ,  H02H7/08 ,  H02P6/00 ,  H02P6/24 ,  G11B19/00

Abstract: PROBLEM TO BE SOLVED: To prevent parasitic effects when the power to a DC motor is turned down during a power-off period of the motor by clamping related power nodes to a reference voltage. SOLUTION: A BEMF control circuit 10 is provided with three input follower means 12, 13, 14, and the three means 12, 13, 14 are basically identical. The circuit 10 monitors the voltage on wires 70, 70', 70" corresponding to low-side driver output nodes A, B, C and continuously compares them with one another. If any one falls below the others, a current is produced via the current path corresponding to the circuit. A mirror circuit corresponding to the current path is provided with a transistor 30, 30' or 30", and a current passing through one of them causes a current passed via a corresponding mirror transistor 46, 46' or 46" to be varied, and controls the current passed through the collector of the respective transistor on the wire 72, 72', or 72". As a result, parasitic effect can be prevented, when power breakdown occurs.