Motor drive circuit

Abstract

A motor drive circuit comprises a first power line; a second power line; an H-bridge circuit that includes a first source transistor and a first sink transistor connected serially, a second source transistor and a second sink transistor connected serially, a motor coil connected at a connection point between the first source transistor and the first sink transistor, and first to fourth regenerative diodes disposed respectively on the first and second source transistors and the first and second sink transistors, the H-bridge circuit being connected between the first power line and the ground, the first source transistor and the second sink transistor being switched complementarily to the second source transistor and the first sink transistor; and a voltage constraint circuit connected between the second power line and control electrodes of the first and second source transistors, the voltage constraint circuit constraining increase in the voltage of the control electrodes of the first and second source transistors to a voltage corresponding to the voltage of the second power line, the first and second source transistors being transistors turned on / off in accordance with a voltage difference between an electrode on the first power line and the control electrode, the voltage of the second power line being a voltage that turns off the second source transistor if a current flows from the first source transistor to the second sink transistor.

Description

technical field [0001] The present invention relates to motor drive circuits. Background technique [0002] As a circuit for driving a motor, an H bridge circuit is generally used. When a motor is driven by an H-bridge circuit, a Zener diode is used to suppress a voltage rise so as not to destroy a MOSFET due to a voltage rise when a kickback occurs (for example, Patent Document 1). [0003] FIG. 10 shows a configuration example of a motor drive circuit that suppresses a voltage rise by using a Zener diode. The motor drive circuit is constituted by including an H-bridge circuit with P-channel MOSFETs 101 and 102 on the power supply side and N-channel MOSFETs 103 and 104 on the ground side. Then, the motor winding 105 is connected between the connection point of the P-channel MOSFET 101 and the N-channel MOSFET 103 and the connection point of the P-channel MOSFET 102 and the N-channel MOSFET 104 . [0004] A power source 110 generating a voltage VA is connected to a power ...

AI Technical Summary

Problems solved by technology

Therefore, the voltage Vm of the power supply line 112 rises

Furthermore, even without the diode 114, the voltage Vm of the power supply line 112 rises when the power supply line 112 is long, etc.

Images