CN102625538B - Constant current LED (light-emitting diode) signal conditioning circuit - Google Patents

Abstract

The constant current LED signal conditioning circuit of the present invention includes a signal input module, a linear conversion module, a current detection module, a voltage limiting module and an electronic switch module. When the signal input module of the present invention does not receive the dimming voltage provided by the user, it has constant current drive and can directly drive the LED lamp; when receiving the dimming signal from the user, it disconnects the connection with the internal current detection reference, and The 1-10V dimming signal voltage is converted into a very linear dimming voltage, which is used to control the light output of the LED lamp, providing users with a more comfortable and pleasant lighting environment.

Description

A Constant Current LED Signal Conditioning Circuit

technical field

The invention relates to the field of LED driving power supply, in particular to a conditioning circuit with internal constant current control and capable of receiving external dimming signals.

Background technique

So far, LED dimming power supply can be divided into analog dimming and digital dimming. Thyristor dimming changes its conduction angle and pollutes the power grid. The PWM dimming frequency is not handled well, and it is easy to generate noise. A power supply that can only receive external dimming signals, when there is no dimming signal voltage, the power supply is difficult to stabilize. When the LED power supply without dimming function receives its external dimming signal, the linearity is very poor, and the scheme is relatively complicated.

The invention patent with application number CN200910039996.6 provides a dimmable LED constant current drive circuit, but the circuit is relatively complicated and the production cost of the circuit board is high.

Contents of the invention

The present invention proposes a signal conditioning circuit capable of receiving dimming signals and internally equipped with constant current control. The circuit includes

The signal input module is used to receive the LED power supply control signal;

A linear conversion module, connected to the signal input module, for linearizing the voltage received by the signal input module, and converting it into a dimming signal voltage that matches the LED power supply;

A current detection module, connected to the linear conversion module, for detecting the input current of the dimming signal of the LED power supply;

A voltage limiting module, connected to the signal input module, for controlling the voltage delivered by the signal input module within a certain range;

The electronic switch module is connected with the voltage limiting module and the current detection module, and is provided with an electronic switch inside. The electronic switch includes a PNP transistor Q1, an NPN transistor Q2 and a control chip. When the signal input module receives a certain When the dimming signal is within the voltage range, the NPN transistor Q2 is first turned on, and then the PNP transistor Q1 is turned on, so that the control chip is turned on, and the current sampling reference is clamped to zero, thereby disconnecting the LED power supply. connection of the current sense reference voltage.

Preferably, the voltage limiting module controls the voltage delivered by the signal input module within 10V; at the same time, the linear conversion module converts the voltage received by the signal (1-10V) input module to match the power supply When the electronic switch module receives a dimming signal of 1-10V, the electronic switch is activated to disconnect the current detection reference voltage in the LED power supply.

The circuit structure of the present invention is simple, and it has a constant current drive and can directly drive the LED lamp when it does not receive the dimming voltage provided by the user; when it receives the dimming signal from the user, it disconnects the connection with the internal current detection reference, and Convert the 1-10V dimming signal voltage into a highly linear dimming voltage, which is used to control the light output of LED lights, providing users with a more comfortable and comfortable lighting environment.

Description of drawings

Accompanying drawing 1 is the module connection schematic diagram of preferred embodiment of the present invention;

Accompanying drawing 2 is the circuit connection schematic diagram of the preferred embodiment of the present invention.

Detailed ways

As shown in Fig. 1, the constant current LED signal conditioning circuit of the present invention includes a signal input module, a linearization conversion module, a current detection module, a voltage limiting module and an electronic switch module, wherein the signal input module is used to receive the LED power supply control signal; linearization The conversion module is connected with the signal input module, and is used to linearize the voltage received by the signal input module and convert it into a dimming signal voltage that matches the LED power supply; the current detection module and the linearization conversion module connected to detect the dimming signal input current of the LED power supply; the voltage limiting module is connected to the signal input module to control the voltage delivered by the signal input module within a certain range; the electronic switch module is connected to the The voltage limiting module is connected to the current detection module, and an electronic switch is arranged inside it. When the signal input module receives a dimming signal within a certain voltage range, the electronic switch disconnects from the current detection reference voltage in the LED power supply. connect.

In the preferred embodiment shown in Figure 2, when the signal input module of this circuit receives a dimming signal of 1-10V, the voltage limiting circuit limits it within 10V; when the electronic switch module receives a dimming signal of 1-10V When the dimming signal is activated, the electronic switch is immediately activated to disconnect the current detection reference voltage inside the LED power supply, and the current of the LED power supply is completely controlled by the dimming signal to achieve the purpose of dimming.

In Fig. 2, the voltage limiting module is mainly composed of a resistor R25 and a Zener diode ZD1. The electronic switch includes a control chip U5, namely TL431, a transistor Q1, a transistor Q2, and several resistors; the linear conversion module includes a high-precision calculation Amplifier OP07 and several resistors. Once the interface J1 receives a 1-10V dimming signal, the transistor Q2 is first turned on, and then the transistor Q1 is turned on, so that the voltage of the control terminal (G) of the control chip U5 is higher than 2.5V, and the control chip U5 is turned on immediately. Clamps the current-sense reference to zero, closing the power supply's internal current-sense loop. After the transistor Q1 is turned on, the power supply (VCC) is regulated by the Zener diode ZD2 and supplied to the chip U6. The linear conversion module composed of U6 and related devices converts the input signal into a signal voltage that matches the LED power supply. It can linearly change the current of the LED power supply to achieve the purpose of controlling the light output of the LED lamp.

The constant current LED signal conditioning circuit of the present invention is used in conjunction with a power supply to provide an LED power supply that not only has constant current control, but also can receive dimming signals. When the signal conditioning circuit of the present invention receives the dimming voltage signal, it performs voltage limiting control, and at the same time turns off the constant current control signal of the power supply, and through the linearization conversion circuit, the linearity of the dimming voltage is improved and has a better dimming effect . The invention also adopts a diode to isolate the constant current detection inside the power supply and the external dimming signal, so that the voltage of the external dimming signal is not disturbed.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than limit the protection scope of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that Modifications or equivalent replacements are made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims (6)

1. a constant-current LED signal conditioning circuit, is characterized in that: described circuit comprises

Signal input module, for receiving LED power control signal;

Linearisation modular converter, is connected with described signal input module, carries out linearizing processing for the voltage that described signal input module is received, and converts the dim signal voltage matching with LED power supply to;

Current detection module, is connected with described linearisation modular converter, for detection of the dim signal input current of described LED power supply;

Pressure limiting module, is connected with described signal input module, for voltage control that described signal input module is transmitted in certain limit;

Electronic switch module, be connected with described pressure limiting module and current detection module, its inside is provided with electronic switch, described electronic switch comprises positive-negative-positive triode Q1, NPN type triode Q2 and control chip, in the time that described signal input module receives the dim signal within the scope of certain voltage, the first conducting of described NPN type triode Q2, positive-negative-positive triode Q1 conducting afterwards, make described control chip conducting, by current sample benchmark clamper to zero, thereby disconnect and being connected of current detecting reference voltage in LED power supply.

2. constant-current LED signal conditioning circuit as claimed in claim 1, is characterized in that: the voltage control that described pressure limiting module is transmitted described signal input module is in 10V.

3. constant-current LED signal conditioning circuit as claimed in claim 1, is characterized in that: the voltage transitions that described linearisation modular converter receives described signal input module becomes the dim signal voltage of 1-10V.

4. constant-current LED signal conditioning circuit as claimed in claim 1, is characterized in that: when described electronic switch module receives the dim signal of 1-10V, start described electronic switch and disconnect and being connected of current detecting reference voltage in described LED power supply.

5. constant-current LED signal conditioning circuit as claimed in claim 1, is characterized in that: described control chip is TL431.

6. constant-current LED signal conditioning circuit as claimed in claim 1, is characterized in that: described linearisation modular converter comprises high precision operating amplifier OP07.