| 摘要 |
PROBLEM TO BE SOLVED: To provide a current sense circuit including a current sense circuit for controlling a motor driven by a H bridge of an electronic switch.SOLUTION: The current sense circuit can include a shunt resistor in which a current to be detected flows. Each of a first and a second differential amplifier can provide an amplified output of a voltage across the shunt resistor. A switching system can send out current sense signal output on the basis of the amplified output of the first differential amplifier when an in-phase voltage across the shunt resistor is low, and on the basis of the amplified output of the second differential amplifier when the in-phase voltage across the shunt resistor is high. The first differential amplifier can supply, when the in-phase voltage is low, a DC offset voltage of its minimum output, and the second differential amplifier can supply, when the in-phase voltage is high, a DC offset voltage of its minimum output. Both of the first and second differential amplifiers have a low in-phase voltage rejection ratio. For example, the ratio at the switching frequency of a switch controlling a current to be detected can be less than 40 db. |
