JPH0533682U - Power circuit - Google Patents

Abstract

(57) [Summary] [Structure] Two error amplifiers 8 and 12 having different reference voltages are provided, and a switch is provided at the input of the error amplifier 12 having the lower reference voltage, depending on the load condition. Open and close. [Effect] Loss can be reduced by lowering the voltage during the waiting period.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a power supply circuit effective for use in a color television receiver or the like.

[0002]

[Prior Art]

 The principle diagram of a switching regulator is shown on page 11 of the switching regulator design know-how, issued in 1985. Only one reference voltage and error amplifier is shown in this figure. Therefore, the output voltage of the switching regulator is a single DC voltage.

[0003]

[Problems to be solved by the device]

 An object of the present invention is to reduce the electric power supplied by the DC voltage to the load.

[0004]

[Means for Solving the Problems]

 To achieve the object, the present invention uses two error amplifiers with different voltage reference voltages. A switch is provided at the input of the error amplifier with the lower reference voltage, and the switch is opened or closed depending on the load condition.

[0005]

[Action]

 When the load is light, for example, when the television receiver is on standby, by opening the switch, the output voltage is reduced to the voltage determined by the lower reference voltage. As a result, the current supplied to the load is reduced and the loss is reduced.

[0006]

【Example】

 FIG. 1 shows an embodiment of the present invention.

The AC voltage is rectified and smoothed by the bridge rectification circuit, and an unstabilized DC voltage is generated across the capacitor 1. This voltage is supplied to the series circuit of the transistor 2 driven by the drive circuit 3 and the primary winding of the switching transformer 4. When the transistor 2 is opened or closed, an AC voltage corresponding to the unstabilized DC voltage is generated at both ends of the primary winding of the switching transformer 4, and at the same time, the flowing current causes magnetic energy to be accumulated in the primary winding. To be done. The voltage generated by the energy transmitted to the secondary winding by opening / closing the transistor 2 is rectified and smoothed by the diode 5 and the capacitor 6, and becomes a DC voltage. This DC voltage is compared with the reference voltage 7, the difference is amplified by the error amplifier 8 and transmitted to the drive circuit 3 via the photocoupler 9. Since the drive circuit 3 controls the opening / closing time of the transistor 2 so that the difference between the DC voltage and the reference voltage 7 becomes zero, the DC voltage becomes a stabilized DC voltage. The regulated DC voltage supplies current to the load (not shown). On the other hand, the error amplifier 8 having a reference voltage 11 lower than the reference voltage 7 is also provided, and a switch 10 is provided at the input.

[0008]

[Effect of the device]

 According to the present invention, the error amplifier 8 operates by closing the switch, and the error amplifier 12 operates by opening the switch. As a result, for example, when the switch is opened during a light load such as when the television receiver is on standby, the error amplifier 12 operates and the stabilized DC voltage decreases. Therefore, the power to the load is reduced and the loss is reduced.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention.

[Explanation of symbols]

1 ... Smoothing capacitor, 2 ... Transistor, 3 ... Drive circuit, 4 ... Switching transformer, 5 ... Diode, 6 ...
Smoothing capacitors, 7, 11 ... Reference voltage, 8, 12 ... Error amplifier, 9 ... Photo coupler, 10 ... Switch.

Claims (1)

[Scope of utility model registration request] 1. A stabilized direct current obtained by switching an unstabilized direct current voltage obtained by rectifying and smoothing an alternating current voltage at a frequency higher than the alternating current voltage and further rectifying and smoothing a switched high frequency voltage. In a switching regulator that converts into a voltage, two error amplifiers having different reference voltages are provided, and a switch provided at the input of the error amplifier having a lower reference voltage causes A power supply circuit characterized by switching output voltage.