Switching power source apparatus
AssigneeSanken Electric Co., Ltd.
InventorAkihiro Uchida
Life of this patent
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Abstract
A switching power source which enables a continuous operation of an apparatus even under an overvoltage test such as a ring wave test. In a case where the sensed voltage (Vb) of the secondary winding (5b) through a diode (D6), the Zener diode (ZD3), and a resistor (R21) to the non-inverting input terminal (+) of a comparator (31), and a high-level signal is inputted to a flip-flop (35) from the comparator (31). As a result, a high-level signal outputted from the Q output terminal is held and outputted to a flip-flop (15) as a reset signal via an OR circuit (37), so that a drive signal kept outputted from the Q output terminal of the flip-flop (15) switches to a low-level one to continue the off-control of the switching element (Q1).
Claims3
A switching power source apparatus (10) that supplies an AC voltage to a step-up reactor (5), ON/OFF-controls a switching element (Q1) connected to an output of the step-up reactor to provide a stepped-up DC voltage hither than the AC voltage, and outputs the DC voltage, comprising:
- ON control means for turning on the switching element in a case where a voltage generated at a secondary coil of the step-up reactor becomes lower than a fist reference voltage;
- error voltage generation means for generating an error voltage made from a difference between a detected value of the output voltage and a second reference voltage;
- current target value generation means for generating a current target value interlocked with a full-wave-rectified waveform of the AC voltage according to the full-wave-rectified waveform and the error voltage;
- and
- OFF control means for turning off the switching element when a current passing through the switching element reaches the current target value, the apparatus characterized by:
- overvoltage protection means for continuously stopping the operation of the switching element only when an overvoltage greater than a third reference voltage is generated at the secondary coil of the step-up reactor.
Dependencies are inferred from the claim text.