Minebea Company, Limited

Eiji Minami

Shigemi Masuda

Takayuki Ohki

There is provided a switching power supply circuit which receives a voltage from a direct current voltage source and supplies a direct current power to a load part. The circuit includes a switching element, a current detection circuit which is serially connected to the switching element, and which converts a current flowing in the switching element into a voltage, a control circuit which outputs a switch driving signal to control an ON/OFF operation of the switching element such that a current flowing in the load part becomes constant, a reference voltage generation circuit which generates a reference voltage proportional to an ON duty of the switch driving signal, and an error amplification circuit which outputs error information between a voltage output from the current detection circuit and the reference voltage. The control circuit adjusts the ON duty of the switch driving signal based on the error information.

Constant current switching power supply

There is provided switching power unit comprising: a PFC voltage detector that detects PFC voltages of the power-factor improvement unit; an output voltage detector that is provided in a current resonance converter unit; a switching controller into which output signals from the PFC voltage detector and output signals from the output voltage detector are input, wherein the switching controller in a full-bridge circuit of first to fourth switching elements, based on output signals from the PFC voltage detector and the output voltage detector, controls the PFC voltages by changing on-duty of the first and second switching elements, and also controls the output voltages by changing switching frequencies of the full-bridge circuit.

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Nagano, Japan

Eiji Minami