CN210327389U

CN210327389U - Voltage adjusting circuit of power output circuit

Info

Publication number: CN210327389U
Application number: CN201921550548.8U
Authority: CN
Inventors: 项军
Original assignee: SHANGHAI ARCATA ELECTRONIC Inc
Current assignee: SHANGHAI ARCATA ELECTRONIC Inc
Priority date: 2019-09-18
Filing date: 2019-09-18
Publication date: 2020-04-14
Anticipated expiration: 2029-09-18

Abstract

The utility model provides a power output circuit's voltage control circuit, at the parallelly connected voltage control circuit of output OUT1 end, voltage control circuit concatenates two divider resistance XR1 at OUT1 output end point, XR2, XR1 respectively with electric capacity XC1, stabilivolt XU1 is connected, stabilivolt XU1 negative pole is connected with PNP triode XQ1 base, PNP triode XQ1 passes through resistance XR3 and is connected with output OUT1 end point, PNP triode XQ1 projecting pole passes through dummy load resistance XR4 and is connected with output OUT1 end point, PNP triode XQ1 collecting electrode ground connection. The utility model has the advantages that, when main output OUT1 underload, when supplementary output OUT2 is full-load, main output OUT 1's output voltage Vout1 floats on, because voltage Vout1 risees to stabilivolt XU1 clamp voltage, triode XQ1 switches on, makes parallelly connected dummy load X54 of main output OUT 1. Limiting the output voltage Vout1 from drifting upward.

Description

Voltage adjusting circuit of power output circuit

Technical Field

The utility model relates to a switching power supply, LED drive circuit power, lighting circuit and digital circuit power, especially relate to the power supply circuit among the LED drive circuit.

Background

Based on safety considerations, the input and output of most current power products require isolation; the PSR topology has the advantages of simple circuit, no optical coupling, CC/CV and cost advantages, and is widely applied to power supply products within 100W, such as the basic block diagram of single output shown in fig. 1.

With the widespread use of sensors, it is more and more common for the output of a common power supply to be added with an independent auxiliary output to supply power to the sensors. For example, as shown in fig. 2, transformer T1 of main circuit output OUT1 adds an auxiliary output OUT 2.

In general, flyback has a problem that one output has good stability, but the voltage without feedback circuit will change dramatically with the change of other loads when multiple outputs are output, which is related to the cross regulation rate of flyback. Taking the two-way output as an example (as shown in fig. 2), when the main circuit output OUT1 is lightly loaded and the auxiliary circuit output OUT2 is fully loaded, the voltage of the main circuit output OUT1 will change dramatically. Therefore, the output voltage of the OUT1 is unstable, and the normal operation of the LED driving circuit is influenced.

Disclosure of Invention

For solving above-mentioned LED drive circuit power supply circuit and having supplementary output OUT2, and influence the stability of main output voltage OUT1, the utility model provides a power output circuit's voltage adjustment circuit, at the parallelly connected voltage adjustment circuit of output OUT1 end, the voltage adjustment circuit is two divider resistance XR1, XR2 of concatenating at OUT1 output end point, XR1 is connected with electric capacity XC1, the controllable accurate steady voltage source XU1 of TL431 respectively, XU 1's negative pole and PNP triode XQ1 base are connected, PNP triode XQ1 is connected with output OUT1 end point through resistance XR3, PNP triode XQ1 projecting pole passes through dummy load resistance XR4 and is connected with output OUT1 end point, PNP triode XQ1 collecting electrode ground connection.

The utility model has the advantages that, when main output OUT1 underload, when supplementary output OUT2 is full-load, main output OUT 1's output voltage Vout1 floats on, because voltage Vout1 risees to TL431 controllable accurate steady voltage source XU 1's clamp voltage, triode XQ1 switches on, makes the parallelly connected dummy load XR4 of main output OUT 1. Limiting the output voltage Vout1 from drifting upward.

Drawings

FIG. 1 is a prior art single output power supply circuit;

FIG. 2 is a two-way output power supply circuit;

FIG. 3 is a voltage regulation circuit of the present invention;

FIG. 4 is a voltage regulation circuit connected in parallel to the two-way output power supply circuit of FIG. 2;

the numbers in the figure indicate CH 1-main output loop, CH 2-auxiliary output loop, OUT 1-output of main output loop, OUT 2-output of auxiliary output loop, and XU1-TL431 controllable precision voltage-stabilizing source.

Detailed Description

Referring to fig. 3, in a normal case, Vout1 does not float upward, and since a clamping voltage of the TL431 controllable precision regulator XU1 is not hit (the clamping voltage is settable, but is slightly greater than the normal case Vout1, and the clamping voltage V =2.5V (XR1/XR2+1)), the stage B and the stage E of the transistor XQ1 are high at the same time, the transistor XQ1 is not turned on, and the dummy load XR4 does not work;

when the main output loop CH1 is lightly loaded and the auxiliary output loop CH2 is fully loaded, and the output voltage Vout1 of the main output CH1 is floating to a certain set value, the stage B of the transistor XQ1 is low, the stage E is high, the transistor XQ1 is turned on, the dummy load XR4 operates, which is equivalent to adding the dummy load XR4 in the CH1 loop, and consuming the energy of the CH1 channel through the dummy load XR4, so as to clamp the Vout1 at the voltage point of the V clamp.

The utility model discloses utilize the reference voltage of the controllable accurate steady voltage source XU1 of TL431 to make the benchmark, replace the stabilivolt of commonly used, generally speaking, the precision of the controllable accurate steady voltage source of TL431 is higher. The output voltage control is more accurate, and the effect is better.

Claims

1. A voltage adjusting circuit of a power output circuit is characterized in that a voltage adjusting circuit is connected in parallel with an output OUT1 end, the voltage adjusting circuit is formed by connecting two divider resistors XR1 and XR2 in series with an output end point of OUT1, the XR1 is respectively connected with a controllable precise voltage-stabilizing source XU1 of a capacitor XC1 and a TL431, the negative electrode of the XU1 is connected with the base electrode of a PNP triode XQ1, the PNP triode XQ1 is connected with an output end point of OUT1 through a resistor XR3, the emitter electrode of the PNP triode XQ1 is connected with the output end point of OUT1 through a dummy load resistor XR4, and the collector electrode of the PNP triode is grounded.