Switching power supply device and the semiconductor integrated circuit for power supply control
First Claim
1. A semiconductor integrated circuit for power supply control for performing switching control of a switching power supply device which switches currents flowing through a primary coil of a transformer for voltage conversion to drive the primary coil with alternate currents and rectifies currents flowing through a secondary coil of the transformer to output DC voltages, wherein the semiconductor integrated circuit generates and outputs a signal for dynamically controlling off-timings of a transistor for synchronous rectification at the secondary coil in accordance with either an input voltage of the primary coil or a load current of the secondary coil, or both of the input voltage of the primary coil and the load current of the secondary coil.
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Accused Products
Abstract
It is aimed at decreasing losses not only in a synchronous rectifier circuit provided at a secondary side of a DC-DC converter, but also in a full-bridge switching circuit provided at a primary side thereof. The DC-DC converter comprises a transformer for voltage conversion, a synchronous rectifier circuit at the secondary side, and a full-bridge switching circuit at the primary side. The DC-DC converter performs synchronous rectifier control which uses switch transistors to change paths of currents flowing through the secondary coil in synchronization with switching operations at the primary side. The DC-DC converter detects currents flowing through a load at the secondary side, primary-side currents varying with the load currents, or primary-side input voltages to dynamically control off-timings of a synchronous rectification transistor at the secondary side. In addition, the DC-DC converter detects primary-side input voltages and currents flowing through the secondary-side load to dynamically control on-timings of a transistor in the primary-side switching circuit.
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Citations
11 Claims
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1. A semiconductor integrated circuit for power supply control for performing switching control of a switching power supply device which switches currents flowing through a primary coil of a transformer for voltage conversion to drive the primary coil with alternate currents and rectifies currents flowing through a secondary coil of the transformer to output DC voltages,
wherein the semiconductor integrated circuit generates and outputs a signal for dynamically controlling off-timings of a transistor for synchronous rectification at the secondary coil in accordance with either an input voltage of the primary coil or a load current of the secondary coil, or both of the input voltage of the primary coil and the load current of the secondary coil.
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10. A semiconductor integrated circuit for power supply control for performing switching control of a switching power supply device which switches currents flowing through a primary coil of a transformer for voltage conversion to drive the primary coil with alternate currents and rectifies currents flowing through a secondary coil of the transformer to output DC voltages,
wherein the semiconductor integrated circuit is configured to be able to set any detection criterion level for a circuit to generate a signal which detects a voltage between terminals of a switching element in a circuit for switching currents flowing through the primary coil and controls on-timings.
Specification