Patent ID: 9042128
Filing Date: 2015-05-26
Classification: H02M,Y02B

Abstract:
1. A switching power source device, comprising: a transformer having a primary winding, a secondary winding, and a tertiary winding; a semiconductor switch that on/off controls a first direct current voltage input into the primary winding with a switching operation; an output voltage generation unit that rectifies and smoothes a secondary winding voltage generated in the secondary winding by the switching operation of the semiconductor switch, generating a second direct current voltage as an output voltage; a power source unit that rectifies and smoothes a tertiary winding voltage generated in the tertiary winding by the switching operation of the semiconductor switch, generating a third direct current voltage; a switching control unit that generates a control signal that controls the switching operation of the semiconductor switch; an output voltage detector unit that detects a transformer voltage based on voltage information of the tertiary winding; and a current detector unit that detects current flowing through the semiconductor switch, wherein the switching power source device supplies a constant output voltage to a load connected to the output voltage generation unit by controlling a turning on and off of the semiconductor switch in accordance with the current detected by the current detector unit and the voltage detected by the output voltage detector unit, includes in the output voltage generation unit a sudden load change detector circuit that detects a drop in the output voltage due to conditions including a sudden load change, outputs a corresponding sudden load change detection signal, and starts a switching in response to the sudden load change detection signal to suppress the drop in the output voltage.