JPS60160082U - Voltage detection circuit in switching power supply circuit - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Brief explanation of the drawing]

Figure 1 shows a conventional switching power supply circuit.
-Circuit diagram, Figure 2 shows smoothing in the power supply circuit of Figure 1,
Figure 3 is a waveform diagram showing the current flowing through the electrolytic capacitor, Figure 3 is a waveform diagram showing the phenomenon of output voltage, and Figure 4 is when a television receiver, etc. is operated using the power supply circuit shown in Figure 1. 5 is a circuit diagram showing the voltage detection circuit in the switching power supply circuit according to the present invention, FIG. 6 is a voltage waveform diagram of each part of the power supply circuit in FIG. 5, and FIG. 7 is a screen diagram showing the image reception state of Explanatory diagram showing the rising state of soft start, Fig. 8c
1 is a waveform diagram showing the rising state of the collector voltage of the output transistor in the power supply circuit of FIG. 5; DESCRIPTION OF SYMBOLS 1... Oscillation part, 2... Control part, 3... Excitation and output shaft, 4... Voltage detection part, 5, 6... Input terminal (unstable input), 7, 8...・Output terminal (stabilized output), 2
6... Output transistor, 28... Smoothing electrolytic continuum 1.32, 34, 36, 38, 42, 43
．． 44... Resistor, 17.35... Constant voltage diode, 37... Control transistor, 41... Voltage comparison transistor, 45... Electrolytic capacitor for oscillation prevention and soft start. -Figure 2 IH7-J -Figure 3- -to H↑2 groaning

Claims (1)

[Scope of claim for utility model registration] Comprising an oscillation section, a control section, an excitation and output shaft, and a voltage detection section,
In a switching power supply circuit that inputs an unstable voltage and outputs a stabilized voltage by switching it and controlling its on period, the voltage detection section is connected between the output voltage terminal and the ground point. A detection resistor circuit connects a plurality of resistors in series to obtain a detection voltage from the connection point thereof, and a detection resistor circuit whose base is connected to the connection point between the resistors and a constant voltage damiode is connected between the emitter and the ground point to obtain a reference voltage and the detection voltage from the connection point. a first transistor that compares the detected voltage with the detected voltage; a voltage source that is connected to the cathode of the constant voltage diode via a resistor to apply a bias to the diode;
a second transistor whose base is supplied with the collector output of the first transistor, whose emitter is connected to the output voltage terminal via a resistor, and whose collector outputs a control voltage to the control section; Among the resistors connected between the output voltage terminals, the resistor is connected between the base of the second transistor and the ground point, and forms an active filter circuit together with the second transistor and the resistor connected to the base of this transistor. A voltage detection circuit in a switching power supply circuit comprising a capacitor.