JPH03120687U - - Google Patents

Description

[Brief explanation of drawings]

FIG. 1 is a configuration block diagram explaining the present invention, FIG. 2 is a configuration block diagram showing an embodiment of the present invention,
Figure 3 is a waveform diagram explaining the operation of the circuit in Figure 2;
FIG. 4 is an equivalent circuit diagram of the correction circuit. FIG. 5 is a block diagram of a conventional device, and FIG. 6 is an explanatory diagram of overload protection. CT...Current transformer, T...Transformer,
n3...Auxiliary winding, Q...Switching element.

Claims (1)

[Claims for Utility Model Registration] A transformer having a primary winding n1 that applies a direct current V _in , a switching element Q that turns on and off the current flowing through the primary winding, and a switching device that appears in the secondary winding n2 of this transformer. A secondary side circuit that rectifies and smoothes a signal and outputs it, and a control circuit provided on the primary side of the transformer that sends a control signal to the switching element to stabilize the voltage V _out output from this secondary side circuit. A switching power supply comprising: a current transformer CT that detects the current flowing through the primary winding; and an auxiliary winding n3 provided on the primary side of the transformer.
and extracts the voltage during the period when the switching element is on from this auxiliary winding, corrects the part of the current detected by the current transformer that depends on the input voltage, and outputs an overload detection signal to the control circuit. An overload protection circuit for a switching power supply, comprising: a correction circuit; and when the correction circuit or the control circuit recognizes an overload state, the switching operation of the switching element is suppressed.