Switching power supply apparatus and power supply control semiconductor integrated circuit
AssigneeMitsumi Electric Co., Ltd.
InventorsMasaki Komatsu, Yuji Yamanaka
Life of this patent
Estimating the term…
Abstract
Disclosed a switching power supply apparatus which includes a voltage converting transformer including an auxiliary winding on a primary side and a switching control circuit, wherein the switching control circuit includes a detection circuit to detect a falling edge of a terminal voltage of the auxiliary winding, and controls a switching transistor connected to a primary winding of the transformer based on the terminal voltage of the auxiliary winding at the time immediately before current flowing through a secondary rectifier diode of the switching power supply apparatus becomes zero, which terminal voltage is obtained based on a detection timing of the detection circuit.
Claims26
A switching power supply apparatus which includes:
- a voltage converting transformer including an auxiliary winding on a primary side and a switching control circuit,
- wherein the switching control circuit includes:
- a detection circuit to detect a falling edge of a terminal voltage of the auxiliary winding, and controls a switching transistor connected to a primary winding of the transformer based on the terminal voltage of the auxiliary winding at the time immediately before current flowing through a secondary rectifier diode of the switching power supply apparatus becomes zero, which terminal voltage is obtained based on a detection timing of the detection circuit.
A power supply control semiconductor integrated circuit which constitutes a switching power supply apparatus to perform switching control of current flowing through a primary winding of a voltage converting transformer including an auxiliary winding on a primary side, to rectify current flowing through a secondary winding of the transformer by a rectifier diode, and to smooth the current by a smoothing condenser so as to output a secondary side voltage,
- wherein the power supply control semiconductor integrated circuit comprises a detection circuit to detect a falling edge of a terminal voltage of the auxiliary winding;
- and
- a switching transistor connected to the primary winding of the transformer is controlled based on the terminal voltage of the auxiliary winding at the time immediately before current flowing through the rectifier diode becomes zero, which terminal voltage is obtained based on a detection timing of the detection circuit.
A switching power supply apparatus which includes a voltage converting transformer including an auxiliary winding on a primary side and a switching control circuit, wherein the switching control circuit includes:
- a detection circuit to detect a falling edge of a terminal voltage of the auxiliary winding to output a pulse;
- a hold section to hold the terminal voltage of the auxiliary winding at the time immediately before the falling edge thereof;
- and
- a sample hold circuit to perform sampling of the voltage held by the hold section based on a detection output of the detection circuit.
- wherein the hold section is a previous stage sample hold circuit to perform sampling of a voltage depending on the terminal voltage of the auxiliary winding based on a pulse signal of a predetermined frequency,
- the previous stage sample hold circuit includes:
- a first sample hold section to perform sampling of a voltage depending on the terminal voltage of the auxiliary winding based on a first pulse signal of a predetermined frequency;
- and
- a second sample hold section to perform sampling of a voltage depending on the terminal voltage of the auxiliary winding based on a second pulse signal the frequency of which is as same as that of the first pulse signal and the phase of which is different from that of the first pulse signal,
- the sample hold circuit includes:
- the third sample hold section to perform sampling of the voltage held by the first sample hold section based on a detection output of the detection circuit;
- and
- the fourth sample hold section to perform sampling of the voltage held by the second sample hold section based on a detection output of the detection circuit,
- a higher voltage among the voltage held by the third sample hold section and the voltage held by the fourth sample hold section is selected as an output of the sample hold circuit,
- a switching transistor connected to a primary winding of the transformer is controlled based on the terminal voltage of the auxiliary winding at the time immediately before current flowing through a secondary rectifier diode of the switching power supply apparatus becomes zero, which terminal voltage is obtained based on a detection timing of the detection circuit, and
- T1 and T2 are set to be T1<T2, where T1 is the time from a falling edge of the first pulse signal to a rising edge of an output pulse of the detection circuit and T2 is the time from a falling edge of the second pulse signal to a rising edge of the first pulse.
Dependencies are inferred from the claim text.