| 摘要 |
PROBLEM TO BE SOLVED: To provide a driver or supplying a trapezoidal waveform current to an electric load so as to furthermore decrease a noise caused by power application/interruption. SOLUTION: A trapezoidal wave generating circuit 21 generates a trapezoidal wave signal Sb according to a drive command signal Sa. A current control circuit 22 controls a MOS transistor Q11 to supply a load current IL equal to the trapezoidal wave signal Sb. A measurement circuit 23 measures a leading time and a trailing time of a voltage across a load I2 in proportional relation to the load current IL, and a gradation control circuit 24 controls a gradual increasing ratio and a gradual decreasing ratio of the trapezoidal wave signal Sb so that the leading time and the trailing time are respectively equal to a reference leading time Ta and a reference trailing time Tb. Clamp circuits 58, 59 limits a rate of change in the trapezoidal wave signal Sb so as not exceed a limit value.
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