CN207665244U - It is a kind of to increase the control circuit for continuously decreasing LED light brightness with temperature - Google Patents

Abstract

The utility model discloses a control circuit for gradually reducing the brightness of an LED lamp as the temperature rises, comprising an LED drive chip, a MOS tube Q1, an LED and an inductor L1, the LED drive chip is connected to the gate of the MOS tube Q1, and the MOS tube Q1 The drain of the diode is connected to the anode of the inductor L1 and the diode D1, the cathode of the diode D1 is connected to the other end of the inductor L1, the resistor R2 and the input power supply VIN, and the source of the MOS transistor Q1 is connected to the resistor R1 and the LED driver chip. The utility model gradually lowers the LED lamp as the temperature rises. By gradually reducing the control scheme and circuit of the LED driving current, the utility model can prevent the LED lamp from being burned (reducing the LED working current can reduce the heating of the system), and can prevent the LED lamp from being burned when it is working. Suddenly extinguish the purpose.

Description

A control circuit that gradually reduces the brightness of LED lights as the temperature rises

technical field

The utility model relates to the technical field of LEDs, in particular to a control circuit for gradually reducing the brightness of an LED lamp as the temperature rises.

Background technique

The temperature of the LED itself or the working environment is too high or it is easy to cause the device to burn out. Some traditional LED lamp driving circuits have a built-in temperature detection module, and when the detected temperature reaches the protection point, the LED driver will be turned off immediately. However, in applications such as car lights, if the lights are immediately extinguished due to temperature rise, it will hinder the use of lighting and even cause traffic accidents.

The present invention needs to solve:

The present invention designs a control scheme and circuit that detects the ambient temperature of the chip and gradually reduces the LED drive current, thereby preventing the LED lamp from being burned (lowering the LED operating current can reduce system heating), and preventing the LED lamp from suddenly Extinguish the purpose.

Utility model content

The purpose of this utility model is to provide a control circuit that gradually reduces the brightness of LED lamps as the temperature rises, so as to solve the problems raised in the above-mentioned background technology.

In order to achieve the above object, the utility model provides the following technical solutions:

A control circuit for gradually reducing the brightness of an LED lamp as the temperature rises, including an LED driver chip, a MOS transistor Q1, an LED, and an inductor L1, the LED driver chip is connected to the gate of the MOS transistor Q1, and the drain of the MOS transistor Q1 is connected to the inductor The anode of L1 and diode D1, the cathode of diode D1 is connected to the other end of inductor L1, resistor R2 and input power supply VIN, the source of MOS transistor Q1 is connected to resistor R1 and LED driver chip.

As a further technical solution of the present invention: the MOS transistor Q1 is an NMOS transistor.

Compared with the prior art, the beneficial effect of the utility model is: the utility model gradually lowers the LED lamp with the increase of temperature by gradually reducing the control scheme and the circuit of the LED drive current, thus achieving the prevention of the LED lamp being burned (lowering the LED lamp). The working current can reduce the heating of the system), and it can also prevent the LED lamp from suddenly going out when it is working.

Description of drawings

Figure 1 is a circuit diagram of the LED constant current control system.

Figure 2 is a circuit diagram of the temperature regulation circuit.

Figure 3 is a graph showing the variation of ref voltage with temperature.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. example. Based on the embodiments of the present utility model, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the scope of protection of the present utility model.

Please refer to Figure 1-3, a control circuit that gradually reduces the brightness of LED lamps as the temperature increases, including LED driver chips, MOS tube Q1, LED and inductor L1, the LED driver chip is connected to the gate of MOS tube Q1, and the MOS tube Q1 The drain of the transistor Q1 is connected to the inductor L1 and the anode of the diode D1, the cathode of the diode D1 is connected to the other end of the inductor L1, the resistor R2 and the input power supply VIN, and the source of the MOS transistor Q1 is connected to the resistor R1 and the LED driver chip.

The working principle of the present utility model is: as shown in Figure 1, in the wire frame is the LED driver chip architecture. By detecting the peak current flowing through the inductor, and then controlling the on-duty ratio of the inductor, the purpose of constant peak current of the inductor is achieved. In CCM mode, the peak current of the inductor is close to the average current of the LED lamp, so the current flowing through the LED lamp constant.

The current I of the LED lamp = ref/R1; ref is the internal reference voltage, and R1 is the sampling resistor.

In order to gradually reduce the LED working current as the temperature rises, we have built-in a temperature detection circuit, and then gradually reduce the REF value, so as to achieve the purpose of gradually reducing the LED lamp current. As shown in Figure 2, the Ibias negative temperature current and Ibias positive temperature current are generated in the chip, and the two currents with different temperature coefficients are subtracted to generate a curve of the ref voltage that we need with temperature, as shown in Figure 3.

It is obvious to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, no matter from all points of view, the embodiments should be regarded as exemplary and non-restrictive, and the scope of the present invention is defined by the appended claims rather than the above description, so it is intended to fall within the scope of the claims All changes within the meaning and range of equivalents of the required elements are included in the present invention. Any reference sign in a claim should not be construed as limiting the claim concerned.

In addition, it should be understood that although this specification is described according to implementation modes, not each implementation mode only contains an independent technical solution, and this description in the specification is only for clarity, and those skilled in the art should take the specification as a whole , the technical solutions in the various embodiments can also be properly combined to form other implementations that can be understood by those skilled in the art.

Claims (2)

1. a kind of increased with temperature continuously decreases the control circuit of LED light brightness, including LED drive chip, metal-oxide-semiconductor Q1, LED and Inductance L1, which is characterized in that the grid of LED drive chip connection metal-oxide-semiconductor Q1, the drain electrode connection inductance L1 of metal-oxide-semiconductor Q1 and The anode of diode D1, the other end, resistance R2 and the input power VIN of the cathode connection inductance L1 of diode D1, metal-oxide-semiconductor Q1's Source electrode connects resistance R1 and LED drive chip.

2. a kind of control circuit continuously decreasing LED light brightness with temperature raising according to claim 1, feature exist In the metal-oxide-semiconductor Q1 is NMOS tube.