CN219164773U - Constant-voltage constant-current LED driving circuit - Google Patents

Abstract

The utility model provides a constant voltage and constant current LED driving circuit, which comprises: the voltage stabilizing chip uses a resistor network, and is controlled by injecting a DAC (digital-to-analog converter) into an FB pin to enable FB feedback to be lower than or higher than a target value, and finally, the voltage of the regulated and stabilized output voltage is achieved; and the current stabilizing chip is used for enabling the LEDs to be connected in series into a feedback circuit of the FB, so that the current stabilizing effect is achieved. The LED driving circuit is used for driving LEDs with higher voltage and current requirements, is low in cost, uses a switch power supply chip MP2457 and an LDO chip TPS7A4901DGNR which are widely used and a cheaper resistor-capacitor, controls a chip, and adds DAC (digital-to-analog converter) regulation in an original resistor network to control the output voltage and current of a circuit network, so that a hardware closed-loop circuit is formed, the response speed is high, and the voltage and current are more stable.

Description

Constant-voltage constant-current LED driving circuit

Technical Field

The utility model relates to the field of driving circuits, in particular to a constant-voltage and constant-current LED driving circuit.

Background

At present, many voltage and current stabilizing circuits output through a resistor network, but the output voltage and current are single, and program control adjustment cannot be performed.

Disclosure of Invention

The present utility model has been made in view of the above-mentioned problems, and has as its object to provide a constant voltage and constant current LED driving circuit which overcomes or at least partially solves the above-mentioned problems.

According to an aspect of the present utility model, there is provided a constant voltage and constant current LED driving circuit, the driving circuit comprising:

the voltage stabilizing chip uses a resistor network, and is controlled by injecting a DAC (digital-to-analog converter) into an FB pin to enable FB feedback to be lower than or higher than a target value, and finally, the voltage of the regulated and stabilized output voltage is achieved;

and the current stabilizing chip is used for enabling the LEDs to be connected in series into a feedback circuit of the FB, so that the current stabilizing effect is achieved.

Optionally, the voltage stabilizing chip adopts MP2457, which meets the low ripple requirement of 0.1%, and has a quiescent current of only 65uA and a fixed switching frequency of 2 MHz.

Optionally, the current stabilizing chip adopts TPS7A4901DGNR, and the LED is connected in series into a feedback circuit of FB by using an original resistance network.

Optionally, the DAC control specifically includes:

the port of the DAC1 is connected with one end of a fifth resistor R5, and the other end of the fifth resistor R5 is connected with the FB pin;

one end of the seventh resistor R7 is connected with the FB pin, and the other end of the seventh resistor R7 is respectively connected with the eleventh resistor R11 and the twelfth resistor R12;

a capacitor C20 is connected in parallel with the fifth resistor R5;

the other end of the twelfth resistor R12 is grounded;

the other end of the eleventh resistor R11 is connected to a power supply.

The utility model provides a constant voltage and constant current LED driving circuit, which comprises:

the voltage stabilizing chip uses a resistor network, and is controlled by injecting a DAC (digital-to-analog converter) into an FB pin to enable FB feedback to be lower than or higher than a target value, and finally, the voltage of the regulated and stabilized output voltage is achieved; and the current stabilizing chip is used for enabling the LEDs to be connected in series into a feedback circuit of the FB, so that the current stabilizing effect is achieved. The LED driving circuit is used for driving LEDs with higher voltage and current requirements, is low in cost, uses a switch power supply chip MP2457 and an LDO chip TPS7A4901DGNR which are widely used and a cheaper resistor-capacitor, controls a chip, and adds DAC (digital-to-analog converter) regulation in an original resistor network to control the output voltage and current of a circuit network, so that a hardware closed-loop circuit is formed, the response speed is high, and the voltage and current are more stable.

The foregoing description is only an overview of the present utility model, and is intended to be implemented in accordance with the teachings of the present utility model in order that the same may be more clearly understood and to make the same and other objects, features and advantages of the present utility model more readily apparent.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present utility model, the drawings required for the description of the embodiments will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present utility model, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a circuit diagram of a voltage stabilizing chip according to an embodiment of the present utility model;

fig. 2 is a circuit diagram of a current stabilizing chip according to an embodiment of the present utility model.

Detailed Description

Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

The terms "comprising" and "having" and any variations thereof in the description embodiments of the utility model and in the claims and drawings are intended to cover a non-exclusive inclusion, such as a series of steps or elements.

The technical scheme of the utility model is further described in detail below with reference to the accompanying drawings and the examples.

As shown in FIG. 1, the voltage stabilizing chip of the utility model adopts MP2457, meets the low ripple requirement of 0.1%, has a quiescent current of only 65uA, has an efficiency of up to 90%, has a fixed switching frequency of up to 2MHz, uses an original resistor network, but injects DAC control into the FB pin to enable FB feedback to be lower or higher than a target value, finally achieves the regulation and stable output voltage, the current stabilizing chip adopts TPS7A4901DGNR, and also uses the original resistor network, but is different in that the LEDs are connected in a feedback circuit of the FB in series, and the feedback of the FB is extremely stable and has a very fast response speed, so that the current stabilizing effect can be achieved finally.

As shown in fig. 2, if the FB pin has no output voltage of VOUT under the condition of DAC1 input, the FB pin always maintains 0.8V as a feedback voltage in chip design, by this principle, the input of DAC1 can be added, so that the voltage of FB pin cannot be maintained at 0.8V, so that the output voltage VOUT of MP2457 can be automatically regulated according to the input of DAC1, so that the voltage of FB pin is maintained at 0.8V, but because the circuit is completely a hardware closed loop, the regulation time is very fast, VOUT voltage reaches a predetermined voltage soon, the regulated voltage basically has no fluctuation, and the load is not disturbed (when the input of DAC1 is low, VOUT voltage increases, when the input of DAC1 is high, VOUT voltage decreases, and a see-saw effect is formed). At this time VOUT is input to TPS7a4901DGNR, according to the principle of previous MP2457, the FB feedback voltage is always maintained at 1.18V without the intervention of the DAC2 pin, and the FB feedback voltage is changed due to the DAC2, but in order to maintain 1.18V, the current between led+ and LED is maintained at a very stable environment, so that the LED is maintained at a very stable constant current state (when the DAC2 input is low, the current flowing between LEDs increases, and when the DAC2 input is high, the current flowing between LEDs decreases, and a see-saw effect is formed).

The beneficial effects are that: a very stable constant-voltage constant-current environment is provided for LED driving, so that the high precision of the instrument is ensured and the service life of the LED is prolonged.

The foregoing detailed description of the utility model has been presented for purposes of illustration and description, and it should be understood that the utility model is not limited to the particular embodiments disclosed, but is intended to cover all modifications, equivalents, alternatives, and improvements within the spirit and principles of the utility model.

Claims (4)

1. A constant voltage and constant current LED driving circuit, comprising:

the voltage stabilizing chip uses a resistor network, and is controlled by injecting a DAC (digital-to-analog converter) into an FB pin to enable FB feedback to be lower than or higher than a target value, and finally, the voltage of the regulated and stabilized output voltage is achieved;

and the current stabilizing chip is used for enabling the LEDs to be connected in series into a feedback circuit of the FB, so that the current stabilizing effect is achieved.

2. The constant voltage and constant current LED driving circuit according to claim 1, wherein the voltage stabilizing chip adopts MP2457, which meets the low ripple requirement of 0.1%, has a quiescent current of only 65uA and has a fixed switching frequency of 2 MHz.

3. The constant voltage and constant current LED driving circuit according to claim 1, wherein the current stabilizing chip adopts TPS7A4901DGNR, and the LEDs are connected in series into a feedback circuit of FB by using an original resistor network.

4. The constant voltage and constant current LED driving circuit according to claim 1, wherein said DAC control specifically comprises:

the port of the DAC1 is connected with one end of a fifth resistor R5, and the other end of the fifth resistor R5 is connected with the FB pin;

one end of the seventh resistor R7 is connected with the FB pin, and the other end of the seventh resistor R7 is respectively connected with the eleventh resistor R11 and the twelfth resistor R12;

a capacitor C20 is connected in parallel with the fifth resistor R5;

the other end of the twelfth resistor R12 is grounded;

the other end of the eleventh resistor R11 is connected to a power supply.

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