JPS6310214A - Power supply circuit - Google Patents

Abstract

PURPOSE:To obtain a power supply circuit which can input various types of voltage with high efficiency by performing the switch between a series regulator system and a switching regulator system. CONSTITUTION:This power supply circuit consists of a switch part 20, a power supply part of a series regulator system, and another power supply part 21 of a switching regulator system. The input voltage is detected by an input detecting circuit 1. When the detected voltage value is equal to 7V or 8V, a switch circuit 2 turns on a control circuit 3 of a series regulator system and turns off a control circuit 4a of a switching regulator system respectively. Thus the power supply is obtained for a series regulator. While the circuit 2 turns on the circuit 4a to obtain the power supply of a switching regulator system when the input voltage is equal to 11V-30V.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a power supply circuit for a programmable controller, for example.

Conventional Technology There are two types of power supply circuits for obtaining stable DC output from DC input: series regulator type and switching regulator type. A series regulator type power supply circuit generally has the configuration shown in FIG. 3, and compares and amplifies the voltage detected by the output voltage detection circuit 12b and the reference voltage of the reference voltage generation circuit 8, so that the difference becomes zero. Like the voltage quality? Control element 6b. That is, it is a power supply circuit that lowers the input voltage Ei by the voltage conversion element 6b to keep a required output voltage constant.

Further, a switching regulator type power supply circuit generally has a configuration as shown in FIG.

This switching regulator system compares the output voltage with a reference voltage, provides a comparison difference to the switching control section 4b, and uses this difference to open and close the swifting element 6b at a frequency that changes the duty ratio of a constant frequency. Furthermore, the power supply circuit maintains the output voltage of the switching element 6b at a constant level using a smoothing circuit composed of a coil 9, a capacitor 10, and a diode 11. Note that 13 is a load.

Problems to be Solved by the Invention However, in a series regulator type power supply circuit, the efficiency of the voltage conversion element 6b usually decreases to about half because the voltage conversion element 6b in FIG. 3 lowers the input voltage Ei to the output voltage. do. Furthermore, as the voltage drop rate increases, the amount of heat generated by the voltage conversion element +csb increases, and the heat sink that radiates this heat must be made larger. Therefore, there are problems in that the cost becomes high and the device becomes large.

In addition, in a switching regulator type power supply circuit, noise is generated by the switching operation of the switching element 6b shown in Fig. 4, so if there is noise-resistant round equipment around the programmable controller in which this switching regulator is used, had the problem of having a negative impact.

Means for Solving the Problems In order to solve the above problems, the present invention provides a power supply circuit that combines both the series regulator system and the switching regulator system, and the series regulator system and the switching regulator system, depending on the value of the input voltage. It consists of a switching circuit that switches the switching regulator method.

For production The effects of the above technical means of the present invention are as follows.

That is, if the programmable controller or its riverside equipment is sensitive to noise, input an input voltage of 7 to 8 V. By doing so, the power supply circuit of the present invention can reduce noise generation because it automatically selects the series regulator system that generates very little noise. Also, if you want to input a high voltage, in the range of 11V to 30V, a series regulator system is inefficient, so a switching regulator system is used as the power source. Therefore, one variety of voltages can be input.

Embodiment An embodiment of the present invention will be explained based on FIGS. 1 and 2.

FIG. 2 shows a power supply circuit in one embodiment of the present invention. In FIG. 2, 1 is an input voltage detection circuit that detects the input voltage E1, 2 is a switching circuit for selecting the series regulator type or the switching regulator type depending on the voltage detected from the input voltage detection circuit 1, and 3
4a is a series regulator type control circuit, 4a is a switching regulator type control circuit, and the smoothing circuit is a coil 9, a capacitor 10. It is composed of a diode 11.

12a is an output voltage detection circuit for detecting the output voltage;
8 is a reference voltage generation circuit that generates a reference voltage of 6V, and 7a is an amplification circuit that takes the difference between the output voltage and the reference voltage and feeds it back to each control circuit 3.4a. 20 is a switching section;
21 is a series regulator type power supply section, and 22 is a switching regulator type power supply section.

First, the input voltage Ei is detected by the input detection circuit 1. If the detected value is from 7v to 8v, the switching circuit 2 turns on the series regulator type control circuit 3 and turns off the switching regulator type control circuit 4a, thereby providing a series regulator type power source. Further, when the input voltage Ei is from 11v to 30v, the switching circuit 2 turns on the switching regulator type control circuit 4a, contrary to the above, and becomes a switching regulator type power source.

Effects of the Invention As described above, according to the embodiments of the present invention, when it is desired to reduce the noise generated from the power supply circuit, the input voltage is set to 7V to 7V.
By inputting 8V, it automatically becomes the power supply for the series regulator, so noise generation can be reduced. Also, if you manually apply a high voltage of 11v to 30V,
Series regulators are inefficient, so they are used as power supplies for switch-closing regulators. Therefore, various voltages can be input.

This results in a highly efficient power supply circuit.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a power supply circuit in an embodiment of the present invention,
Figure 2 is a graph showing the series regulator area and switching regulator area with respect to input voltage.
FIG. 4 is a block diagram of a conventional general series regulator type power supply circuit, and FIG. 4 is a block diagram of a conventional general switching regulator type power supply circuit. 2o...Switching unit, 21...Series regulator type power supply unit, 22...Switching regulator type power supply unit. Name of agent: Patent attorney Toshio Koo and 1 other person/Z Figure 2

Claims (1)

[Claims] A voltage conversion element comprising a first circuit that generates a reference voltage, a second circuit that detects an output voltage, and a third circuit that compares and amplifies the reference voltage and the output voltage, and that is controlled by the difference in comparison in the third circuit. A series regulator type power supply section having a first circuit that generates the reference voltage, a second circuit that detects the output voltage, a third circuit that compares and amplifies the output voltage, and converts the comparison difference in the third circuit into a certain frequency. and a switching element whose opening/closing is controlled by the frequency,
A switching regulator type power supply unit having a smoothing circuit that smoothes the output of the switching element, a fifth circuit that detects input voltage, and switching between the series regulator type power supply unit and the series regulator type power supply unit depending on the input voltage. A power supply circuit with a switching section.