| 摘要 |
<p>PROBLEM TO BE SOLVED: To prevent an erroneous overcurrent protection operation by the incorrect detection of an overcurrent if a voltage amplifier having a large delay is used to amplify an overcurrent detection voltage.SOLUTION: A switching power supply includes: a non-isolated DC-DC converter of a synchronous rectification method, including a main switch TR1, a commutation switch TR2, an output choke coil L1, an output smoothing capacitor C1; an overcurrent detector circuit including a voltage amplifier IC2 for amplifying a current detection voltage generated in a series equivalent resistance R1 of the output choke coil L1, and a PWM controller IC2 for reading an overcurrent detection voltage, to thereby perform overcurrent protection operation when the overcurrent detection voltage exceeds an overcurrent determination value; and a forcible synchronization switch TR3 to forcibly switch on/off the output of the voltage amplifier IC2, provided in the overcurrent detection circuit, synchronously with the commutation switch TR2.</p> |
