CN214381487U

CN214381487U - LED driver

Info

Publication number: CN214381487U
Application number: CN202023023109.7U
Authority: CN
Inventors: 刘新明
Original assignee: Guangdong NRE Technology Co Ltd
Current assignee: Guangdong NRE Technology Co Ltd
Priority date: 2020-12-15
Filing date: 2020-12-15
Publication date: 2021-10-08
Anticipated expiration: 2030-12-15

Abstract

The utility model relates to a LED driver, which is an IC drive circuit driven by an LED drive chip U1, wherein the LED drive chip U1 is provided with a linear dimming pin as input and an enabling end; the LED driver is provided with a comparator U2B, one input end of the comparator U2B is connected with a linear dimming pin, the other input end of the comparator U2B is connected with a reference voltage VA, and the output end of the comparator U2 is connected with an enabling end; the linear dimming pin is connected with the positive input end of the comparator U2B, so that the enable end is active at high level, and the voltage of the linear dimming pin is connected with the negative input end of the comparator U2B, so that the enable end is active at low level; the reference voltage VA is not less than the starting voltage of the linear dimming pin, and the starting voltage is at least more than 0.1 mV. The utility model discloses a linear dimming foot of LED driver is easily received the fluctuating analog signal conversion of disturbance big and is the switching signal of enabling the end, and the control enables the end and forbids the enabling to realize the scope of adjusting luminance for 0% -100%, can turn-off when making the LED driver adjust luminance, strengthened the stability that the LED driver adjusted luminance effectively.

Description

LED driver

Technical Field

The utility model belongs to the technical field of the LED field and specifically relates to a LED driver.

Background

Traditional led low voltage input lamp cup (for example, MR16) is restricted by the inner space, and when dimming is realized, external input source with dimming mode is adopted, such as dimming with thyristor electronic transformer, constant voltage four-in-one dimming, etc. In the mode, when the dimming is the lowest, the input power source is in a light load or no-load state, the amplitude and the pulse of the input voltage of the lamp cup are not very stable, so that the input detection of the DC-DC constant current circuit of the lamp cup is inaccurate, and the flicker phenomenon is easily caused between the low current of the lamp cup and the turn-off of the lamp cup.

The conventional solution is to sacrifice dimming depth (without switching off) to ensure stability.

SUMMERY OF THE UTILITY MODEL

The utility model discloses a purpose is guaranteeing to realize under the condition that can turn-off when the LED driver adjusts luminance, the stability that the LED driver adjusted luminance is strengthened.

The utility model discloses a following technical scheme realizes:

an LED driver is provided, the LED driver is an IC driving circuit driven by an LED driving chip U1, the LED driving chip U1 has a linear dimming pin as an input and is provided with an enabling end; the LED driver is provided with a comparator U2B, one input end of the comparator U2B is connected with a linear dimming pin, the other input end of the comparator U2B is connected with a reference voltage VA, and the output end of the comparator U2 is connected with the enabling end; the linear dimming pin is connected with the positive input end of the comparator U2B, so that the high level of the enable end is effective, and the voltage of the linear dimming pin is connected with the reverse input end of the comparator U2B, so that the low level of the enable end is effective; the reference voltage VA is not less than the starting voltage of the linear dimming pin, and the starting voltage is at least greater than 0.1 mV.

Further, the comparator U2B is a hysteresis comparator.

Further, the LED driver is provided with a signal isolation device U2A, and the linear dimming pin is connected to the comparator U2B through the signal isolation device U2A.

Further, the signal isolation device U2A is a follower.

Further, the hysteresis voltage of the hysteresis comparator is 0.2V.

Further, the reference voltage VA is greater than the turn-on voltage of the linear dimming pin.

Further, the turn-on voltage of the linear dimming pin is 0.4V.

Further, the reference voltage VA is 0.5V.

Further, the LED driver is a buck IC driver circuit, and the LED driving chip U1 has a SW pin to implement a switching output.

The utility model discloses a linear dimming foot of LED driver is easily received the fluctuating analog signal conversion of interference and is the switching signal of enabling end, control enable end forbids the enable to the realization scope of adjusting luminance is 0% -100%, can turn-off when making LED driver adjust luminance, has strengthened the stability that the LED driver adjusted luminance effectively.

The above description is only an overview of the technical solutions of the present invention, and in order to make the technical means of the present invention more clearly understood, the present invention can be implemented according to the content of the description, and in order to make the said and other objects, features and advantages of the present invention more obvious and understandable, the following detailed description of the present invention is given.

Drawings

Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the invention. Also, like reference numerals are used to refer to like elements throughout the drawings.

In the drawings:

fig. 1 is a schematic circuit diagram of an LED driver according to the present invention.

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.

Example 1

In order to change the dimming range of the LED driver from 5-100% to 0-100%, the LED driver is stable and can be turned off during dimming, and the LED driver is improved by the embodiment. Specifically, as shown in fig. 1, the LED driver employs a buck IC driver circuit, where the IC is an LED driver chip U1, the chip U1 inputs based on its DIM pin, implements a switching output through its SW pin, and has an EN pin providing chip enable control.

In the above, the EN pin of the chip U1 is an enable terminal, the high level is active, and the low level is off; the SW pin is a switch output end and is used for outputting a switch signal; the DIM pin is a linear dimming pin with a turn-on voltage of 0.4V, i.e., the IC itself can achieve a larger dimming range.

In the improvement, a comparator U2B is added between an EN pin and a DIM pin of a chip U1, specifically, a signal of the DIM pin is connected to a positive input end of a comparator U2B, an output end of the comparator U2B is connected with the EN pin, and a reference voltage VA exceeding 0.4V is supplied to a negative input end of the comparator U2B. When ordinary external dimmer was transferred from big to little, when the VB voltage of DIM foot was higher than reference voltage VA, comparator U2B output high level given the EN foot, and the LED lamp can normally realize adjusting luminance, and when external dimmer transferred to VB voltage and was less than reference voltage VA, comparator U2B overturns, outputs the low level, makes the LED lamp turn-off. When the dimmer is adjusted from small to large, and the VB voltage is greater than the reference voltage VA, the EN pin is at high level, the IC is started, and the circuit works. Therefore, the dimming range of the LED driver is changed from 5-100% to 0-100%, the LED driver can be turned off when dimming is realized, and the IC is forbidden when the LED driver is turned off, so that the power consumption can be reduced.

In the above, the reference voltage VA may be obtained by dividing the voltage by the resistors R1 and R2, and the voltage division ratio is set so that the reference voltage VA is maintained at 0.5V.

Furthermore, in order to prevent the lamp cup from dimming and flickering due to the fact that the VB voltage jumps back and forth at the reference voltage VA, the comparator U2B can be improved to be a hysteresis comparator, 0.2V hysteresis voltage is set to be used as allowance, and when the dimmer is adjusted from small to large, the VB voltage is larger than 0.7V, and the EN pin has high level to enable the circuit to work. In the embodiment, the hysteresis voltage of 0.2V is set to improve the anti-interference capability, so that the lamp cup is ensured to be dimmed, has no flicker phenomenon and can be turned off.

In order to prevent the DIM pin and the EN pin from affecting each other, a signal isolation device U2A is designed, and the DIM pin is connected to the positive input terminal of the comparator U2B through the signal isolation device U2A, so as to realize signal isolation between the DIM pin and the EN pin.

As an embodiment, the signal isolation device U2A may be a diode, an optocoupler, a follower, or the like, wherein the follower is preferred.

This embodiment is through improving the LED driver, and the analog signal that the DIM foot is easily disturbed fluctuation big changes and converts the switching signal of EN foot, and the EN foot of control U1 makes the LED lamp can turn off for the low level to realize that the dimming range is 0% -100%.

Example 2

In embodiment 2, based on embodiment 1, the signal of the DIM pin is switched to the inverting input terminal of the comparator U2B, the reference voltage VA is switched to the inverting input terminal, and the EN pin is designed to be active at low level and off at high level, which also achieves the technical effect.

It should be finally noted that the above embodiments are only intended to illustrate the technical solutions of the present invention, and not to limit the scope of the present invention, and although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solutions of the present invention can be modified or replaced with equivalents without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A kind of LED driver is disclosed, which comprises a LED chip,

the LED driver is an IC (integrated circuit) driving circuit driven by an LED driving chip U1, and the LED driving chip U1 is provided with a linear dimming pin as an input and an enabling end;

the method is characterized in that:

the LED driver is provided with a comparator U2B, one input end of the comparator U2B is connected with a linear dimming pin, the other input end of the comparator U2B is connected with a reference voltage VA, and the output end of the comparator U2 is connected with the enabling end;

the linear dimming pin is connected with the positive input end of the comparator U2B, so that the high level of the enable end is effective, and the voltage of the linear dimming pin is connected with the reverse input end of the comparator U2B, so that the low level of the enable end is effective;

the reference voltage VA is not less than the starting voltage of the linear dimming pin, and the starting voltage is at least greater than 0.1 mV.

2. The LED driver of claim 1, wherein: the comparator U2B is a hysteretic comparator.

3. The LED driver of claim 2, wherein: the LED driver is provided with a signal isolation device U2A, and the linear dimming pin is connected to a comparator U2B through the signal isolation device U2A.

4. The LED driver of claim 3, wherein: the signal isolation device U2A is a follower.

5. The LED driver of claim 2, wherein: the hysteresis voltage of the hysteresis comparator is 0.2V.

6. The LED driver of claim 1, wherein: the reference voltage VA is greater than the turn-on voltage of the linear dimming pin.

7. The LED driver of claim 6, wherein: the turn-on voltage of the linear dimming pin is 0.4V.

8. The LED driver of claim 7, wherein: the reference voltage VA is 0.5V.

9. The LED driver of claim 7 or 8, wherein: the LED driver is a buck IC driver circuit, and the LED driver chip U1 has an SW pin to implement a switching output.