A backlight circuit based on an LED driving chip

Abstract

The utility model provides a kind of backlight circuit based on LED driver chip belongs to backlight circuit technical field, including drive circuit and be set on rectifier voltage stabilizing circuit and resistance network of drive circuit, the drive circuit includes drive chip U5, capacitor C20 and resistance R11, the rectifier voltage stabilizing circuit includes diode D9, inductance L3, capacitor C19 and capacitor C63, the resistance network includes resistance R12, resistance R13 and resistance R14.The utility model, the circuit is based on LED driver chip, and intelligent adjustment of backlight is realized by program control, power supply stability is ensured using switching power supply architecture and multistage filter circuit, integrated overcurrent protection and feedback voltage stabilizing mechanism, with efficient, reliable, low power consumption etc. Characteristics, applicable to the robot display screen backlight scene under complex environment.

Description

Technical Field

[0001] This utility model relates to the field of backlight circuit technology, and more specifically, to a backlight circuit based on an LED driver chip. Background Technology

[0002] In special robot remote control systems, the backlight circuit of the display screen needs to have the characteristics of high reliability, low power consumption and fast response.

[0003] Existing traditional backlight circuits mostly employ simple resistor current limiting or constant voltage driving methods, which suffer from problems such as inflexible brightness adjustment and low energy efficiency. Furthermore, special robots operate in complex environments, requiring backlight circuits to also possess anti-interference and voltage regulation functions. Therefore, inventing a backlight circuit based on LED driver chips to solve these problems has become a pressing issue for those skilled in the art. Utility Model Content

[0004] To overcome the above shortcomings, this utility model provides a backlight circuit based on an LED driver chip, which aims to solve the problem that the backlight circuit also needs to have anti-interference and voltage regulation functions in the complex working environment of special robots.

[0005] This utility model is implemented as follows:

[0006] This circuit is based on an LED driver chip and achieves intelligent backlight adjustment through program control. It utilizes a switching power supply architecture and multi-stage filtering circuits to ensure stable power supply, integrates overcurrent protection and feedback voltage regulation mechanisms, and features high efficiency, reliability, and low power consumption. It is suitable for robot display backlight scenarios in complex environments.

[0007] This utility model provides a backlight circuit based on an LED driver chip, including a driver circuit and a rectifier and voltage regulator circuit and a resistor network disposed on the driver circuit. The driver circuit includes a driver chip U5, a capacitor C20 and a resistor R11.

[0008] The rectifier and voltage regulator circuit includes diode D9, inductor L3, capacitor C19 and capacitor C63;

[0009] The resistor network includes resistors R12, R13, and R14.

[0010] Preferably, the GND pin of the driver chip U5 is grounded, the IN pin of the driver chip U5 is connected to the power supply and capacitor C20, the output terminal of the capacitor C20 is grounded, the FB pin of the driver chip U5 is connected to resistor R11, and the other end of the resistor R11 is grounded.

[0011] Preferably, one end of the inductor L3 is connected to the IN pin of the driver chip U5, the other end of the inductor L3 is connected to the positive terminal of the diode D9, the capacitors C19 and C63 are connected in parallel and grounded, and the negative terminal of the diode D9 outputs the BL_VCC power supply.

[0012] Preferably, resistors R12 and R13 are connected in series to the EN / PWM pin of driver chip U5, one end of resistors R12 and R13 is grounded, and the pin between resistors R12 and R13 is connected to the enable signal LCD_BL pin.

[0013] Preferably, the LX pin of the driver chip U5 is connected to the positive terminal of the diode D9, and the OVP pin of the driver chip U5 is connected to the negative terminal of the diode D9.

[0014] By adopting the above technical solution, the driver chip U5 acts as the control center of the backlight circuit. Based on the externally input enable signal (LCD_BL) and feedback signal (FB pin), it converts the input 5V voltage (VCC5V) into a high voltage (BL_VCC) suitable for the LED through the high-frequency on / off of the internal switching transistor, thus achieving enable control. It receives external signals through the EN / PWM pin (controlling whether the chip works (enables) or adjusts the backlight brightness), and samples the output voltage through the feedback resistor R11 (0.91R) on the FB pin to achieve closed-loop feedback control, ensuring stable output voltage. The rectifier and voltage regulator circuit converts the input voltage into a stable operating voltage, ensuring the normal operation of the LED driver chip and the LED. When the BL_VCC voltage exceeds the OVP threshold (e.g., 15V), the OVP pin of U5 detects the abnormal voltage, the internal comparator triggers the latch, forcibly turning off the switching transistor, and simultaneously outputs an alarm signal through the FAULT pin (if present). If the LED string is short-circuited or the L3 current exceeds the chip's rated value (e.g., 1.5A), U5... The internal current detection circuit triggers protection, shutting down the switching transistor to prevent the chip and inductor from overheating and burning out. When the chip junction temperature exceeds 140°C, the internal temperature sensor is activated, forcing the chip into a sleep state. It automatically restarts when the temperature drops below 120°C.

[0015] The beneficial effects of this utility model are:

[0016] This circuit is based on an LED driver chip and achieves intelligent backlight adjustment through program control. It utilizes a switching power supply architecture and multi-stage filtering circuits to ensure stable power supply, integrates overcurrent protection and feedback voltage regulation mechanisms, and features high efficiency, reliability, and low power consumption. It is suitable for robot display backlight scenarios in complex environments. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this utility model and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.

[0018] Figure 1 This is a backlight circuit diagram based on an LED driver chip provided by an embodiment of the present invention;

[0019] Figure 2 This is a schematic diagram of a backlight circuit based on an LED driver chip provided by an embodiment of the present invention. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this utility model.

[0021] Example, refer to Figures 1-2 A backlight circuit based on an LED driver chip includes a driver circuit and a rectifier and voltage regulator circuit and a resistor network disposed on the driver circuit. The driver circuit includes a driver chip U5, a capacitor C20 and a resistor R11.

[0022] The rectifier and voltage regulator circuit includes diode D9, inductor L3, capacitor C19 and capacitor C63;

[0023] The resistor network includes resistors R12, R13, and R14.

[0024] Furthermore; the GND pin of the driver chip U5 is grounded, the IN pin of the driver chip U5 is connected to the power supply and capacitor C20, the output terminal of capacitor C20 is grounded, the FB pin of the driver chip U5 is connected to resistor R11, the other end of resistor R11 is grounded, one end of inductor L3 is connected to the IN pin of the driver chip U5, the other end of inductor L3 is connected to the positive terminal of diode D9, capacitors C19 and C63 are connected in parallel and then grounded, the negative terminal of diode D9 outputs the BL_VCC power supply, resistors R12 and R13 are connected in series to the EN / PWM pin of the driver chip U5, one end of resistors R12 and R13 connected in series is grounded, the pin between resistors R12 and R13 is connected to the enable signal LCD_BL pin, the LX pin of the driver chip U5 is connected to the positive terminal of diode D9, and the OVP pin of the driver chip U5 is connected to the negative terminal of diode D9.

[0025] It should be noted that: C20 is a ceramic capacitor with low equivalent series resistance, connected in parallel between the IN pin of the driver chip U5 and ground. Its function is to filter out high-frequency noise in the input power supply VCC5V, ensuring a stable 5V input voltage for the IN pin of the driver chip U5, and preventing power fluctuations from causing internal logic disorder or malfunction of the switching transistor. Inductor L3, C19, and C63 form a typical filter circuit. Inductor L3 presents high impedance to AC signals, blocking high-frequency ripple from passing through, while C19 and C63 present low impedance to AC signals, providing a path to ground for the ripple. This hierarchical filtering mechanism can suppress the output voltage ripple amplitude to below 50mV, meeting the stringent requirements of LED backlight for power supply purity. Diode D9 is a Schottky diode, characterized by low forward voltage drop and fast recovery speed. It acts as a rectifier in the circuit, preventing reverse current flow when inductor L3 releases energy, ensuring the stability of the output voltage BL_VCC. Meanwhile, resistor R11... One end is connected to the FB pin, and the other end is grounded. The output voltage is adjusted through voltage divider feedback. Resistors R12 and R13 divide the enable signal LCD_BL, thereby controlling the EN / PWM pin of chip U5 to realize enable control and dimming functions. By adjusting the duty cycle of the LCD_BL signal, the average voltage of the EN / PWM pin can be changed, thereby controlling the conduction time of the internal switch of U5. When the duty cycle increases, the conduction time of the switch is extended, the energy stored in inductor L3 increases, the output voltage of BL_VCC increases, and the LED brightness increases. Conversely, the brightness decreases. This dimming method adjusts brightness by changing the average current of the LED, avoiding the color shift problem of analog dimming. R14 is not connected and can be reserved for subsequent circuit adjustment and function expansion. Chip U5 is a switching power supply chip. Through internal switching transistor control, together with external inductors, capacitors and other components, it converts the input VCC5V voltage into a stable BL_VCC output voltage to power the load. The OVP pin is used to monitor the output voltage or the voltage of critical nodes. When the voltage exceeds the preset safety threshold, the protection mechanism is triggered to prevent the circuit from being damaged or malfunctioning due to overvoltage.

[0026] The driver chip U5 acts as the control center of the backlight circuit. Based on the externally input enable signal (LCD_BL) and feedback signal (FB pin), it converts the input 5V voltage (VCC5V) into a high voltage (BL_VCC) suitable for the LEDs through the high-frequency on / off of the internal switching transistor, thus achieving enable control. It receives external signals through the EN / PWM pin to control whether the chip is working (enabled) or to adjust the backlight brightness. Simultaneously, it samples the output voltage through the feedback resistor R11 (0.91R) on the FB pin to achieve closed-loop feedback control, ensuring stable output voltage. The rectifier and voltage regulator circuit converts the input voltage into a stable operating voltage, ensuring the normal operation of the LED driver chip and the LEDs. When the BL_VCC voltage exceeds the OVP threshold (e.g., 15V), the OVP pin of U5 detects the abnormal voltage, the internal comparator triggers the latch, forcibly turning off the switching transistor, and simultaneously outputs an alarm signal through the FAULT pin (if present). If the LED string is short-circuited or the L3 current exceeds the chip's rated value (e.g., 1.5A), U5... The internal current detection circuit triggers protection, shutting down the switching transistor to prevent the chip and inductor from overheating and burning out. When the chip junction temperature exceeds 140°C, the internal temperature sensor is activated, forcing the chip into a sleep state. It automatically restarts when the temperature drops below 120°C.

[0027] The working principle of this backlight circuit based on an LED driver chip:

[0028] This circuit is based on an LED driver chip and achieves intelligent backlight adjustment through program control. It utilizes a switching power supply architecture and multi-stage filtering circuits to ensure stable power supply, integrates overcurrent protection and feedback voltage regulation mechanisms, and features high efficiency, reliability, and low power consumption. It is suitable for robot display backlight scenarios in complex environments.

[0029] The above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A backlight circuit based on an LED driver chip, comprising a driver circuit and a rectifier and voltage regulator circuit and a resistor network disposed on the driver circuit, characterized in that, The driving circuit includes a driving chip U5, a capacitor C20, and a resistor R11; The rectifier and voltage regulator circuit includes diode D9, inductor L3, capacitor C19 and capacitor C63; The resistor network includes resistors R12, R13, and R14.

2. The backlight circuit based on an LED driver chip according to claim 1, characterized in that, The GND pin of the driver chip U5 is grounded, the IN pin of the driver chip U5 is connected to the power supply and capacitor C20, the output terminal of capacitor C20 is grounded, the FB pin of the driver chip U5 is connected to resistor R11, and the other end of resistor R11 is grounded.

3. A backlight circuit based on an LED driver chip according to claim 2, characterized in that, One end of the inductor L3 is connected to the IN pin of the driver chip U5, and the other end of the inductor L3 is connected to the positive terminal of the diode D9. The capacitors C19 and C63 are connected in parallel and grounded. The negative terminal of the diode D9 outputs the BL_VCC power supply.

4. A backlight circuit based on an LED driver chip according to claim 3, characterized in that, The resistors R12 and R13 are connected in series to the EN / PWM pin of the driver chip U5. One end of the series connection of resistors R12 and R13 is grounded. The pin between resistors R12 and R13 is connected to the enable signal LCD_BL pin.

5. A backlight circuit based on an LED driver chip according to claim 4, characterized in that, The LX pin of the driver chip U5 is connected to the positive terminal of the diode D9, and the OVP pin of the driver chip U5 is connected to the negative terminal of the diode D9.

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