CN212909348U

CN212909348U - Feedback circuit used in power supply voltage reduction chip

Info

Publication number: CN212909348U
Application number: CN202021627084.9U
Authority: CN
Inventors: 姚超; 郑继清
Original assignee: Chengdu Create Automotive Electronics Co ltd
Current assignee: Chengdu Create Automotive Electronics Co ltd
Priority date: 2020-08-07
Filing date: 2020-08-07
Publication date: 2021-04-06
Anticipated expiration: 2030-08-07

Abstract

The utility model discloses a feedback circuit for in power step-down chip, including opto-coupler U1 and steady voltage source U2, steady voltage source U2's negative pole is connected to the negative pole of opto-coupler U1 transmitting terminal, the positive pole of opto-coupler U1 transmitting terminal is connected to the circuit input end through resistance R3, the circuit input end still is in proper order through resistance R1, resistance R5 ground connection, resistance R5 is connected to resistance R1's one end and still is connected to steady voltage source U2's reference pole, steady voltage source U2's positive pole ground connection, the projecting pole ground connection of opto-coupler U1's receiving terminal, the collecting electrode of its receiving terminal is connected to the circuit output end. The utility model has the advantages of adopt the opto-coupler to keep apart to use steady voltage source U2 to combine the feedback, not only can avoid output voltage to exert an influence to the input, but also the accuracy is tested input voltage.

Description

Feedback circuit used in power supply voltage reduction chip

Technical Field

The utility model relates to a signal processing circuit, concretely relates to feedback circuit for in power step-down chip.

Background

The power supply chip comprises two types, namely AC-DC and DC-DC, wherein the AC-DC is a chip for converting alternating current into direct current, the DC-DC is a chip for converting direct current into direct current, and the power supply chip is divided into a voltage reduction chip and a voltage boosting chip according to the change of voltage.

In the existing voltage reduction chip, high voltage is converted into low voltage for the electronic instrument at the low voltage end to use, and a feedback circuit is generally arranged for testing whether the output voltage of the output end is correct or not, if the output voltage is not correct, the existing feedback circuit is provided with a diode which ensures the unidirectional circulation of signals, but negative voltage is also connected into the low voltage end circuit through the feedback circuit in series, and the electronic instrument at the low voltage end is burnt.

SUMMERY OF THE UTILITY MODEL

It is an object of the present invention to solve at least the above problems and to provide at least the advantages which will be described later.

An object of the utility model is to provide a feedback circuit for among power step-down chip is gone into for solving the unable reply negative pressure cluster of current feedback circuit to burn out low pressure end electronic instrument's problem.

In order to realize the objects and other advantages according to the present invention, a feedback circuit for use in a power supply voltage reduction chip is provided, including an optocoupler U1 and a regulated voltage source U2, a cathode of the regulated voltage source U2 is connected to a cathode of an emitting end of the optocoupler U1, an anode of the emitting end of the optocoupler U1 is connected to a circuit input end through a resistor R3, the circuit input end is further grounded through a resistor R1 and a resistor R5 in sequence, one end of the resistor R5 connected to the resistor R1 is further connected to a reference electrode of the regulated voltage source U2, an anode of the regulated voltage source U2 is grounded, an emitter of a receiving end of the optocoupler U1 is grounded, and a collector of the receiving end is.

This feedback circuit adopts the opto-coupler feedback, through opto-coupler U1 and steady voltage source U2, when guaranteeing accurate test input end voltage, can also avoid the voltage of output terminal department to produce the influence to the input.

In one possible design, a resistor R4 and a capacitor C2 are connected in series between the reference pole and the cathode of the regulator U2. The resistor R4 and the capacitor C2 which are connected in series are used as phase compensation of the voltage stabilizing source U2.

In one possible design, a capacitor C3 is provided between the reference pole and the cathode of the regulator U2. The capacitor C3 is used for phase compensation of the regulator U2, and is backup to the resistor R4 and the capacitor C2.

In one possible design, a capacitor C1 is connected in parallel with the receiving end of the optical coupler U1. The capacitor C1 is used to filter out noise.

In a possible design, a resistor R7 is arranged between the collector of the receiving end of the optical coupler U1 and the circuit output end, and two ends of the resistor R7 are further grounded through a capacitor C5 and a capacitor C6, respectively. The resistor R7, the capacitor C5 and the capacitor C6 are combined into a pi-type filter, the effect of filtering out clutter is achieved, the resistance-type filter is adopted, the structure is small, and the cost is reduced.

In one possible design, the resistor R1 is connected in parallel with a capacitor C4. The impedance of high-frequency signals is reduced, and the signal transmission response speed is improved.

In a possible design, the cathode of the voltage regulator U2 is further connected to the anode of the emitting end of the optocoupler U1 through a resistor R2, so that current is additionally injected into the voltage regulator U2, and the voltage regulator U2 is prevented from being incapable of working due to the fact that the injected current is too small.

The utility model discloses at least, include following beneficial effect: in the circuit, an optical coupler is used for isolation, and a voltage stabilizing source U2 is used for combining feedback, so that the influence of the voltage of an output end on an input end can be avoided, and the voltage of the input end can be accurately tested; the output end of the circuit is provided with a filter capacitor and a pi-type filter, so that the interference of the output end of the circuit is reduced.

Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention.

Drawings

FIG. 1 is a block diagram of the present invention;

fig. 2 is a schematic circuit diagram of a processor.

Detailed Description

The invention will be further described with reference to the accompanying drawings and specific embodiments. It should be noted that the description of the embodiments is provided to help understanding of the present invention, but the present invention is not limited to the description. Specific structural and functional details disclosed herein are merely illustrative of example embodiments of the invention. The present invention may, however, be embodied in many alternate forms and should not be construed as limited to the embodiments set forth herein.

It is to be noted that the experimental methods described in the following embodiments are all conventional methods unless otherwise specified, and the reagents and materials, if not otherwise specified, are commercially available; in the description of the present invention, the terms "lateral", "longitudinal", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplicity of description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore, should not be construed as limiting the present invention.

As shown in fig. 1 and 2, a feedback circuit for a power supply voltage reduction chip includes an optocoupler U1 and a regulator U2, a cathode of the regulator U2 is connected to a negative electrode of an emitting end of the optocoupler U1, an anode of the emitting end of the optocoupler U1 is connected to a circuit input end through a resistor R3, the circuit input end is further grounded through a resistor R1 and a resistor R5 in sequence, one end of the resistor R5 connected to a resistor R1 is further connected to a reference electrode of the regulator U2, an anode of the regulator U2 is grounded, an emitter of a receiving end of the optocoupler U1 is grounded, and a collector of the receiving end is connected to a circuit output end.

The circuit input end is used for being connected to the output voltage after the step-down chip steps down, and output voltage is the low pressure end electronic instrument power supply, and the circuit output end is used for connecting the test port of step-down chip.

For example, the voltage of 5V is required to be output, and the voltage of 5V is divided by R1 and R5 through the input end of the circuit, and the voltage entering the reference pole of the voltage regulator U2 is the voltage on R5. The voltage at the input end of the circuit is grounded after passing through a resistor R3, an optical coupler emitting end and a voltage stabilizing source U2.

When the voltage at the input end of the circuit is increased, the reference voltage of the voltage regulator U2 is increased, the voltage of the cathode of the voltage regulator U2 is reduced, the current at the emitting end of the optocoupler U1 is increased, the current at the receiving end of the optocoupler U1 is increased, the duty ratio of the receiving end is reduced, and therefore the voltage at the output end of the circuit is reduced; when the voltage at the input end of the circuit is reduced, the voltage of a reference electrode of the voltage-stabilizing source U2 is reduced, the voltage of a cathode of the voltage-stabilizing source U2 is increased, the current at the emitting end of the optocoupler U1 is reduced, the current at the receiving end of the optocoupler U1 is increased, the duty ratio of the end is increased, and the voltage at the output end of the circuit is increased. By the method, the voltage reduction chip obtains the voltage change condition of the circuit input end, and accordingly adjusts.

In the circuit, a voltage stabilizing source U2 is in a model number of TL 431-A; the type of the optocoupler U1 is PC 817; the present circuit may serve as a buck chip OB2338 SP. The output end of the circuit is connected to the FB end in the voltage reduction chip.

While the embodiments of the invention have been described above, it is not intended to be limited to the details shown, or described, but rather to cover all modifications, which would come within the scope of the appended claims, and all changes which come within the meaning and range of equivalency of the art are therefore intended to be embraced therein.

Claims

1. A feedback circuit used in a power supply voltage reduction chip is characterized by comprising an optical coupler U1 and a voltage stabilization source U2, wherein the cathode of the voltage stabilization source U2 is connected to the negative electrode of the emitting end of the optical coupler U1, the positive electrode of the emitting end of the optical coupler U1 is connected to the input end of the circuit through a resistor R3, the input end of the circuit is sequentially grounded through a resistor R1 and a resistor R5, one end of the resistor R5, which is connected to a resistor R1, is also connected to the reference electrode of the voltage stabilization source U2, the anode of the voltage stabilization source U2 is grounded, the emitter of the receiving end of the optical coupler U1 is grounded, and the collector of.

2. The circuit as claimed in claim 1, wherein a resistor R4 and a capacitor C2 are connected in series between the reference pole and the cathode of the regulated power supply U2.

3. The circuit as claimed in claim 1 or 2, wherein a capacitor C3 is provided between the reference pole and the cathode of the regulator U2.

4. The circuit as claimed in claim 1, wherein a receiving end of the optocoupler U1 is connected in parallel with a capacitor C1.

5. The circuit as claimed in claim 1 or 4, wherein a resistor R7 is arranged between the collector of the receiving end of the optocoupler U1 and the circuit output end, and two ends of the resistor R7 are further grounded through a capacitor C5 and a capacitor C6 respectively.

6. The circuit as claimed in claim 1, wherein a capacitor C4 is connected in parallel to the resistor R1.

7. The circuit as claimed in claim 1, wherein the cathode of the regulator U2 is further connected to the anode of the emitting terminal of the optocoupler U1 via a resistor R2.