JPH0255573A - Power source control circuit - Google Patents

Abstract

PURPOSE:To reduce the number of parts by converting an analog output voltage into a digital amount then performing control of a power source through a microcomputer from the thus produced digital signal. CONSTITUTION:In a power source control circuit, power fed from an input power source is rectified through a primary rectifier circuit 1 comprising a full-wave rectifier and fed through 8 capacitor C1 to a switching circuit 2. The switching circuit 2 performs switching control ot the power with a predetermined period through a timer 7 set with an initial value/thus converting the power into AC power having a constant frequency. Then the converted power is fed to a down transformer 3 and taken out as a DC output from a secondary rectifier circuit 4, C2. The DC output is fed to an A/D converter 5 and an overvoltage detecting circuit 8 thence to a microprocessor 6, where it is compared with a reference value and the operational period of the timer 7 is controlled such that the difference will be zero.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a power supply control circuit, and more particularly to a power supply control circuit that feedbanks output power to an input side and controls the output voltage to be set at a constant value.

(Prior Art) Conventionally, this type of power supply control circuit converts an input voltage into an AC signal with a switching period that operates at a predetermined period, then obtains a DC output voltage through a rectifier, rectifier, and smoothing circuit, and converts this DC There was a circuit that compared the output voltage with a reference voltage and controlled the operating cycle of the switching cycle based on the difference between the two voltages.

(Problem to be solved by the invention) As described above, the conventional power supply control circuit treats the DC output voltage as an analog value and controls the switching period by comparing this analog signal with the reference analog signal. There is. Therefore, since conventional voltage control circuits treat signals for voltage control as analog signals, it is impossible to generate different constant voltages using the same component. Various special parts are required in response to this. As a result, there is a drawback that it is difficult to respond widely and appropriately to fluctuations in input voltage.

(Means for Solving Overload Problems) A power supply control circuit according to the present invention converts an output voltage value of the power supply control circuit into a digital signal in a power supply control circuit that obtains a predetermined constant output voltage by switching an input voltage. The A/D converter circuit receives the digital signal output from the A/D converter circuit, compares the digital signal with the pressure signal, and performs the switching process based on the comparison result. and a processor that controls the cycle.

(Example) Examples of the present invention will be described below with reference to the drawings.

FIG. 1 is a circuit diagram showing an embodiment of a power supply control circuit according to the present invention.

The case where the input power source is AC will be explained. The input power is
For example, as shown in the figure, the signal is rectified by a primary side rectifier circuit 1 consisting of an aftereffect rectifier circuit, and is input to a switching circuit 2 via a capacitor C1. The switching circuit 2 is controlled to switch at a predetermined period by a timer 7 to which an initial value is set, and converts the signal into alternating current at a constant frequency. The signal thus converted to AC is normally stepped down by a transformer 3, and then rectified and smoothed by a diode 4 and a capacitor C2 that constitute a secondary rectifier circuit to obtain a DC signal with less noise as an output signal. This rectified and smoothed signal is supplied to an A/D converter 5 and an overcurrent/overvoltage detection circuit 8. The A/D converter 5 converts an analog DC signal obtained by a rectifying and smoothing circuit comprising a diode 4 and a capacitor C2 into a digital signal, and inputs the digital signal to the microprocessor 6. Microprocessor (CP)
U) 6 has a built-in program that specifies signal processing to always maintain the output voltage at a constant value, and compares the output voltage with a reference value and sets the timer 7 to eliminate the difference between the two. control the operating cycle of the That is, the timer 7 is
A control signal is sent to the timer 7 to control the operating cycle of the switching circuit 2 and maintain the output voltage at a constant value. The overcurrent/overvoltage detection circuit 8 monitors the voltage value and current value of the output signal, and when the value is excessive, it sends a signal indicating this to the microprocessor 6, and the processing by the microprocessor 6 is performed. An immediate interruption is made, for example, emergency measures such as stopping the operation of the timer 7 are performed.

(Effects of the Invention) As explained above, the present invention converts the output voltage, which is an analog quantity, into a digital quantity, and uses a microcomputer to control the power supply based on the obtained digital signal. By simply using the same power supply for voltage settings and various input voltage settings, and by simply changing or replacing the software (program) built into the microcomputer, you can easily handle a wide range of voltage settings and various input voltage settings. Detection can also be easily handled by using interrupt processing. Moreover, the present invention is an A/D
The above objective can be achieved simply by adding a converter and a microprocessor, and the number of components required for this purpose can be significantly reduced compared to conventional scales.It is also a significant improvement in terms of functionality.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of a power supply control circuit according to the present invention. 1...-next side rectifier circuit, 2... switching circuit,
3...Transformer, 4...Secondary side rectifier circuit, 5...
A/D converter, 6... microprocessor, 7.
...Timer~, 8...Overcurrent, overvoltage detection circuit.

Claims (1)

[Claims] A power supply control circuit that obtains a predetermined constant output voltage by performing switching processing on an input voltage includes an A/D conversion circuit that converts an output voltage value of the power supply control circuit into a digital signal, and an output of this A/D conversion circuit. A power supply control circuit comprising: a processor that receives a digital signal, compares the digital signal with a reference voltage signal, and controls an operation cycle of the switching process based on the comparison result.