CN210609803U

CN210609803U - Self-adaptive driving circuit for LED lamp string

Info

Publication number: CN210609803U
Application number: CN201921753094.4U
Authority: CN
Inventors: 钟留敏; 王玉伟; 许斌; 金伟峰; 徐朋兵
Original assignee: Suzhou Xijieyi Electronics Co Ltd
Current assignee: Suzhou Xijieyi Electronics Co Ltd
Priority date: 2019-10-18
Filing date: 2019-10-18
Publication date: 2020-05-22
Anticipated expiration: 2029-10-18

Abstract

The utility model relates to a self-adaptation drive circuit for LED lamp cluster, the voltage that the power was exported is in proper order through filter circuit, a rectifying circuit, see off from output port behind the secondary filter circuit, be provided with the transformer between filter circuit and rectifier circuit, the rear end of output port is equipped with sampling feedback circuit, sampling feedback circuit's output inserts current-voltage control circuit, current-voltage control circuit's output links to each other with the MOS switch, the work of MOS switch re-control transformer, wherein, current-voltage control circuit control MOS switch carries out fast-speed switching on and ends, turn into the alternating current of high-frequency with the direct current and provide the transformer and carry out the vary voltage. The utility model is suitable for a demand of drive high power LED lamp cluster to have functions such as output excessive pressure/overcurrent protection, the return circuit is simple, reliable, can guarantee that LED lamp cluster can normally work steadily.

Description

Self-adaptive driving circuit for LED lamp string

Technical Field

The utility model relates to an electronic circuit drive control technical field especially relates to a self-adaptation drive circuit for LED lamp cluster.

Background

The LED light source has many advantages such as long service life, small volume, low power consumption, low operating temperature, and the like, and thus is widely used in LED lighting and LED display products. The brightness of the LED lamp is related to the driving current, and in the detection equipment of the liquid crystal display panel, the backlight module BLU can be used, and compared with the common illumination, the BLU needs larger current and more LED lamp beads, so that higher requirements are put forward on the driving board for driving the BLU.

For small-sized BLUs or a small number of lamp beads, the power requirement is low, the voltage requirement is low, generally, the voltage requirement is only dozens of volts, but for large-sized BLUs or a large number of lamp beads, high-power lamp beads are needed to drive an LED lamp string, and 150 volts or even higher voltage is needed. In comparison, only the PWM driving energy storage inductor needed in the small-sized BLU is required to boost voltage, but when the driving capability of requiring higher voltage is required, the mode cannot achieve the ideal effect, so a novel boost circuit is required to adapt to and drive the LED lamp strings with different quantity and size.

SUMMERY OF THE UTILITY MODEL

The utility model aims at providing a self-adaptation drive circuit for LED lamp cluster, its demand that is applicable to drive high power LED lamp cluster to have functions such as output excessive pressure/overcurrent protection, the return circuit is simple, reliable, can guarantee that LED lamp cluster can normally work steadily.

In order to achieve the above purpose, the utility model adopts the technical scheme that:

the utility model provides a self-adaptation drive circuit for LED lamp cluster, including the power, the voltage that the power exported is seen off from the output port after filter circuit, rectifier circuit, secondary filter circuit in proper order, finally accomplishes the output, and this self-adaptation drive circuit still includes transformer, current-voltage control circuit, MOS switch and sampling feedback circuit, the transformer sets up in between filter circuit and the rectifier circuit, sampling feedback circuit sets up in the rear end of output port, the output of sampling feedback circuit inserts current-voltage control circuit, the output of current-voltage control circuit with the MOS switch links to each other, the MOS switch is again controlled the work of transformer, wherein, current-voltage control circuit controls the MOS switch carries out fast-speed through sending PWM square wave, turns into the alternating current of high-frequency with the direct current and provides the transformer with vary voltage, thereby generating the required high voltage.

Preferably, the current-voltage control circuit adopts a special backlight driving chip MP3391, which includes circuits such as boost driving pulse formation, boost driving, PWM dimming, boost MOS transistor overcurrent protection, input undervoltage protection, output overvoltage protection, string overcurrent protection, and dimming MOS field effect power transistors.

Further, the power supply outputs 24V voltage, the voltage output threshold of the transformer is 24V-175V, and the output current is 120 ma.

Because of the application of the technical scheme, compared with the prior art, the utility model has the following advantages:

the utility model discloses a self-adaptation drive circuit for LED lamp cluster, it controls MOS switch (field effect transistor) through the current-voltage control circuit that the driver chip that is shaded constitutes and carries out fast-speed switching on and end, turns into the alternating current of high-frequency with the direct current and provides the transformer and carry out the vary voltage to produce required high-voltage, combine the current feedback to carry out the voltage output adjustment of self-adaptation, whole drive circuit's simple structure, to the drive of lamp cluster reliably and safety.

Drawings

Some specific embodiments of the present invention will be described in detail hereinafter, by way of illustration and not by way of limitation, with reference to the accompanying drawings. The same reference numbers in the drawings identify the same or similar elements or components. Those skilled in the art will appreciate that the drawings are not necessarily drawn to scale. In the drawings:

fig. 1 is a schematic block diagram of an adaptive driving circuit for an LED light string according to an embodiment of the present invention;

FIG. 2 is a schematic circuit diagram of a current-voltage control circuit of the adaptive driving circuit for LED light string shown in FIG. 1;

fig. 3 is a schematic diagram of an operating circuit of the MOS switch in the adaptive driving circuit for the LED light string shown in fig. 1.

Detailed Description

The technical solution of the present invention will be described clearly and completely with reference to the accompanying drawings, and obviously, the described embodiments are some, but not all embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative work belong to the protection scope of the present invention.

In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplification of description, but do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

Furthermore, the technical features mentioned in the different embodiments of the invention described below can be combined with each other as long as they do not conflict with each other.

The embodiment describes a self-adaptive driving circuit for an LED lamp string, as shown in FIG. 1, which includes a power supply, wherein a voltage output by the power supply sequentially passes through a filter circuit, a rectifier circuit, a secondary filter circuit and then is sent out from an output port to finally complete output, the self-adaptive driving circuit further includes a transformer, a current-voltage control circuit, an MOS switch and a sampling feedback circuit, the transformer is disposed between the filter circuit and the rectifier circuit, the sampling feedback circuit is disposed at the rear end of the output port, the output end of the sampling feedback circuit is connected to the current-voltage control circuit, the output end of the current-voltage control circuit is connected to the MOS switch, the MOS switch controls the operation of the transformer, wherein the current-voltage control circuit controls the MOS switch to conduct and stop at high speed by sending out a PWM square wave, the direct current is converted into high-frequency alternating current which is provided for a transformer to transform, so that the required high voltage is generated.

Specifically, the current-voltage control circuit adopts a special backlight driving chip MP3391 as shown in fig. 2, which includes circuits such as boost driving pulse formation, boost driving, PWM dimming, boost MOS transistor overcurrent protection, input undervoltage protection, output overvoltage protection, string overcurrent protection, and dimming MOS field effect power transistors. The power supply outputs 24V voltage, the voltage output threshold of the transformer is 24V-175V, and the output current is 120 ma.

In the adaptive driving circuit for LED light string of this embodiment, the current-voltage control circuit formed by the backlight driving chip controls the MOS switch (field effect transistor) to conduct and stop at high speed, and converts the direct current into the high-frequency alternating current to be supplied to the transformer for voltage transformation, so as to generate the required high voltage, as shown in fig. 3.

In this embodiment, as shown in fig. 3, the +24V power voltage inputted from the outside is sent to the power supply terminal 2 pin of the backlight driving chip MP3391 and the primary coil terminal of the transformer through the fuse and the filter circuit, respectively, the +24V is divided and then received to the 5 pin EN enable terminal of the backlight driving chip MP3391, the oscillation circuit in the MP3391 starts to operate, and the shaped switch excitation pulse signal is outputted from the 25 pin of the MP3391 and sent to the G electrode of the MOS switch Q2 (AOD 254) from R3, so that the MOS switch operates in the on-off state. The backlight driving chip MP3391 controls the MOS switch to turn on and off at high speed, and further converts the direct current into high-frequency alternating current to be supplied to the transformer for voltage transformation, and finally generates the required high voltage (alternating current). The alternating current is rectified by a diode and filtered by LC, and high-voltage direct current for driving an LED is output.

The generated high-voltage direct current is divided into two paths: one path is sent to the LED lamp string socket, the other path is sent to a voltage division circuit composed of R1, R4, R15 and the like, output overvoltage sampling voltage is obtained and sent to an output overvoltage protection detection end 22 pin of MP3391, and the tail end of the LED lamp string on the backlight plate is connected with pins 13-20 of the MP 3391. Under the control of external brightness switch pulse, the backlight brightness control tube in the MP3391 is conducted, that is, the voltage supplied by the lamp string is passed through the LED lamp string and the power MOS tube in the MP3391 to form current to the ground, and the four LED lamp strings are lighted.

Wherein, the current setting: i is_LED= 1000 x 1.23V / R_SETThe current value of each channel is set at the ISET pin of MP 3391.

In addition, after the voltage is divided by the overvoltage sampling resistors R1, R4 and R15, the divided voltage is added to the 22 pin of the MP3391, and if the voltage exceeds + 1.24V, the 10 pin of the MP3391 is triggered to charge the C22 (the charging current is 50 muA), so that the 10 pin voltage of the MP3391 is increased. Meanwhile, MP3391 closes the switching pulse output by pin 25, thus realizing output overvoltage protection.

When the output or LED is short-circuited to the ground, after voltage is divided by the overvoltage sampling resistors R1, R4 and R15, the voltage of the pin 22 added to the MP3391 is reduced to + 0.08V, the output short-circuit function to the ground is started, and then the MP3391 closes the switching pulse output by the pin 25. Normal operation can be resumed only if the short circuit is eliminated. Thus, output-to-ground short circuit protection is realized.

In summary, the adaptive driving circuit for LED light strings of the present embodiment combines current feedback to perform adaptive voltage output adjustment, and the whole driving circuit has a simple structure and is reliable and safe for driving the light strings.

The above embodiments are only for illustrating the technical concept and features of the present invention, and the purpose thereof is to enable those skilled in the art to understand the contents of the present invention and to implement the present invention, so as not to limit the protection scope of the present invention, and all equivalent changes or modifications made according to the spirit of the present invention should be covered by the protection scope of the present invention.

Claims

1. A self-adaptive drive circuit for LED lamp strings comprises a power supply, wherein the voltage output by the power supply is sequentially transmitted from an output port through a filter circuit, a rectifier circuit and a secondary filter circuit to finally complete output, and is characterized by further comprising a transformer, a current-voltage control circuit, an MOS switch and a sampling feedback circuit, wherein the transformer is arranged between the filter circuit and the rectifier circuit, the sampling feedback circuit is arranged at the rear end of the output port, the output end of the sampling feedback circuit is connected to the current-voltage control circuit, the output end of the current-voltage control circuit is connected with the MOS switch, the MOS switch controls the work of the transformer, the current-voltage control circuit controls the MOS switch to be switched on and off at high speed by sending PWM square waves, and the direct current is converted into high-frequency alternating current to be provided to the transformer for voltage transformation, thereby generating the required high voltage.

2. The adaptive driving circuit for LED lamp strings according to claim 1, wherein the current and voltage control circuit employs a special backlight driving chip MP3391, which contains circuits such as boost driving pulse formation, boost driving, PWM dimming, boost MOS over-current protection, input under-voltage protection, output over-voltage protection, lamp string over-current protection, etc., and dimming MOS field effect power transistors.

3. The adaptive driving circuit for LED lamp string according to claim 1 or 2, wherein the power supply outputs a voltage of 24V, the voltage output threshold of the transformer is 24V-175V, and the output current is 120 ma.