CN211880668U

CN211880668U - DC-DC type LED lamp dimming control circuit

Info

Publication number: CN211880668U
Application number: CN202021009018.5U
Authority: CN
Inventors: 徐全忠; 欧景春; 陈庆强
Original assignee: Dongguan Xinqu Electronic Technology Co ltd
Current assignee: Dongguan Xinqu Electronic Technology Co ltd
Priority date: 2020-06-05
Filing date: 2020-06-05
Publication date: 2020-11-06
Anticipated expiration: 2030-06-05

Abstract

The utility model discloses a DC-DC LED lamp dimming control circuit, which is used for receiving PWM signals output by a PWM signal source to adjust the brightness of an LED lamp and comprises a driving chip, an LED lamp, a switch tube, an inductor and a diode; the DC power supply VDD, the LED lamp and the switching tube are connected in series to form a first loop, and the control end of the switching tube is electrically connected with the PWM signal source; the DC power supply VDD provides working voltage for the driving chip, and the PWM input end of the driving chip is electrically connected with the PWM signal source; the DC power supply VDD is connected with a reverse diode and an inductor L1 in series to form a second loop, and the inductor is connected with the LED lamp and the switching tube in series to form a third loop; the PWM signal source at least comprises one or more of high level, low level and pulse signals. The utility model discloses a switch tube of establishing ties on the LED lamp makes and whether have the electric current to flow through on can controlling the LED lamp when PWM adjusts luminance the signal change to make LED luminance change linearly along with the change of PWM signal duty cycle of adjusting luminance.

Description

DC-DC type LED lamp dimming control circuit

Technical Field

The utility model relates to a LED lamp technical field that adjusts luminance, especially a DC-DC formula LED lamp control circuit that adjusts luminance.

Background

At present, for the driving and dimming of a high-power LED lamp, a DC-DC conversion circuit is mostly used, which has high power utilization efficiency and is the mainstream application direction, but there is a defect in PWM dimming application, when the driving current exceeds the set LED driving current value, the switching tube of the LED driving circuit is turned off, and during the period of turning off the switching tube of the LED driving circuit, the change of the PWM dimming signal has no influence on the brightness of the LED, so that the dimming linearity of the LED lamp is deteriorated. Because the inductor current flows through the LED, causing the LED to emit light, whether the PWM dimming signal is on or off. This causes the brightness of the LED lamp to change stepwise with the change of the duty ratio of the PWM dimming signal, which is not acceptable in the place of the brightness change of the LED lamp with high demand.

SUMMERY OF THE UTILITY MODEL

The to-be-solved technical problem of the utility model is to above-mentioned prior art not enough, provide a DC-DC formula LED lamp dimming control circuit.

In order to solve the technical problem, the utility model discloses the technical scheme who takes is: a DC-DC type LED lamp dimming control circuit is used for receiving a PWM signal output by a PWM signal source to regulate the brightness of an LED lamp and comprises the LED lamp and a switching tube; the DC power supply, the LED lamp and the switching tube are connected in series to form a first loop, and the control end of the switching tube is electrically connected with the PWM signal source; the PWM signal source at least comprises one or more of high level, low level and pulse signals.

In the above technical solution, the device further comprises an inductor current leakage loop, wherein the inductor current leakage loop comprises a diode and an inductor; the DC power supply is connected with the reverse diode and the inductor in series to form a second loop, and the inductor is connected with the LED lamp and the switch tube in series to form a third loop.

In the above technical solution, the switch tube includes a first switch tube and a second switch tube, a control end of the second switch tube is electrically connected to the PWM signal source, an input end of the second switch tube is electrically connected to a control end of the first switch tube, and the second switch tube controls on/off of the first switch tube; the DC power supply, the LED lamp and the first switch tube are connected in series to form the first loop.

The utility model has the advantages that: the LED lamp is controlled to have current flowing through when the PWM dimming signal changes through the switching tube connected in series with the LED lamp, so that the LED brightness changes linearly along with the change of the duty ratio of the PWM dimming signal. In addition, in order to solve the problem of energy storage on the inductor, an inductor current leakage loop is added, and after the LED lamp is turned off, redundant energy on the inductor is released, so that the efficiency of the whole driving circuit is improved.

Drawings

Fig. 1 is a schematic circuit diagram of embodiment 1 of the present invention.

Fig. 2 is a schematic circuit diagram according to embodiment 2 of the present invention.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings.

As shown in embodiment 1 of fig. 1, a DC-DC type LED lamp dimming control circuit for receiving a PWM signal output from a PWM signal source to adjust the brightness of an LED lamp includes a driving chip U2, an LED lamp, a switching tube Q1, an inductor L1, and a diode; the DC power supply VDD, the LED lamp and the switching tube Q1 are connected in series to form a first loop, and the control end of the switching tube is electrically connected with the PWM signal source; the DC power supply VDD provides working voltage for the driving chip U2, and the PWM input end of the driving chip U2 is electrically connected with the PWM signal source; the DC power supply VDD is connected with a reverse diode and an inductor L1 in series to form a second loop, and the inductor L1 is connected with the LED lamp and the switching tube in series to form a third loop; the PWM signal source at least comprises one or more of high level, low level and pulse signals. In example 1, the diode is denoted by the symbol D5, and in example 2 described below, the diode is denoted by the symbol D1. The LED lamp consists of an LED 1-4.

As shown in embodiment 2 of fig. 2, the switching tube includes a switching tube Q1 and a switching tube Q2, a control end of the switching tube Q2 is electrically connected to the PWM signal source, an input end of the switching tube Q2 is electrically connected to a control end of the switching tube Q1, and the switching tube Q2 controls on/off of the switching tube Q1; the DC power supply VDD, the LED lamp and the switching tube Q1 are connected in series to form the first loop. A pull-up resistor R4 is connected in series to the control terminal of the switching transistor Q2, and a pull-up resistor R3 is connected in series to the control terminal of the switching transistor Q1.

The utility model discloses a theory of operation:

when the PWM signal is at a low level, the driver and the switching tube are switched off, and the LED lamp is not on.

When the PWM signal is at a high level, the driver works, the switching tube is conducted, and the LED lamp is on.

When the PWM signal is a pulse signal, the driver works and the switching tube is switched on during a high level period, the LED lamp is on, and even if the LED current exceeds a set value to cause the driver to be switched off, the LED lamp is still on because the switching tube connected in series with the LED lamp is switched on, the inductive current is released through the LED; and when the PWM signal is at a low level, the driver is turned off and the switching tube is turned off, the inductive current is released back to the power supply through the diode, and the LED lamp does not have current to pass but is not bright, so that good linearity of the LED brightness and the PWM duty ratio is realized.

The above embodiments are merely illustrative and not restrictive, and all equivalent changes and modifications made by the methods described in the claims are intended to be included within the scope of the present invention.

Claims

1. A DC-DC type LED lamp dimming control circuit is used for receiving a PWM signal output by a PWM signal source to adjust the brightness of an LED lamp, and is characterized in that: the LED lamp comprises an LED lamp and a switch tube; the DC power supply, the LED lamp and the switching tube are connected in series to form a first loop, and the control end of the switching tube is electrically connected with the PWM signal source; the PWM signal source at least comprises one or more of high level, low level and pulse signals.

2. The dimming control circuit of claim 1, wherein: the inductor current leakage circuit comprises a diode and an inductor; the DC power supply is connected with the reverse diode and the inductor in series to form a second loop, and the inductor is connected with the LED lamp and the switch tube in series to form a third loop.

3. The dimming control circuit of claim 1, wherein: the switch tube comprises a first switch tube and a second switch tube, the control end of the second switch tube is electrically connected with the PWM signal source, the input end of the second switch tube is electrically connected with the control end of the first switch tube, and the second switch tube controls the on-off of the first switch tube; the DC power supply, the LED lamp and the first switch tube are connected in series to form the first loop.