Panasonic Corporation

Tomohiro Kume

Hisanori Nagase

A reference voltage generator includes: a reference voltage sourcethat generates a direct-current voltage that is used as a reference; a low-pass filterthat is connected to an output node of the reference voltage source; a first voltage buffer circuitwith an input terminal to which the output node of the reference voltage source is connected and an output terminal to which an output node of the low-pass filter is connected, which has a voltage gain of one time; and a hysteresis comparatorwith one input terminal to which the output node of the reference voltage source is connected and an other input terminal to which the output node of the low-pass filter is connected. At start-up, during a time period in which a voltage difference between an output of the reference voltage source and an output of the low-pass filter exceeds a predetermined value, an output impedance of the first voltage buffer circuit is controlled based on an output signal of the hysteresis comparator. At start-up, the low-pass filter that reduces noise is charged with a low impedance rapidly, and thus an output voltage can be stabilized rapidly.

Reference voltage generator

A first voltage-to-current converter converts a difference voltage between a command voltage and a reference voltage into a current. A second voltage-to-current converter converts a difference voltage between a positive output terminal and a negative output terminal of a PWM drive apparatus into a current. A low-pass filter is connected to a connection point between an output terminal of the first voltage-to-current converter and an output terminal of the second voltage-to-current converter. An amplifier amplifies a difference voltage between a voltage at the connection point and a reference voltage. A PWM modulator PWM-modulates an output voltage of the amplifier. A drive section drives a load in accordance with an output signal of the PWM modulator.

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Osaka, Japan

Tomohiro Kume