CN-122028251-A - LED driving circuit and LED driving system

CN122028251ACN 122028251 ACN122028251 ACN 122028251ACN-122028251-A

Abstract

The application belongs to the technical field of electronic circuits, and provides an LED driving circuit and an LED driving system. The output resistor module in the driving circuit comprises n switch units and n resistor units, the second input end of the error amplifying module is respectively connected with the first end of the switch module and the n resistor units, the output end of the error amplifying module is connected with the control end of the switch module, the second end of the switch module is connected with the negative electrode of the LED lamp, the n resistor units are connected with the n switch units in a one-to-one correspondence manner, and the n switch units are grounded. The total output impedance of the output resistor module is kept constant, and the output resistor module determines the conducting number of the switch units according to the output current of the LED lamp, so that the corresponding number of resistor units are connected with the ground in a conducting mode. Through the design, the output impedance of the output resistor module is larger than the total output impedance of the output resistor module, so that the current error caused by mismatched voltage is effectively reduced, and the current control precision and the working stability of a display product are obviously improved.

Inventors

YIN CHENLONG
CHEN JIANZHONG
YOU JIAN
CAO BUYU

Assignees

深圳市微源半导体股份有限公司

Dates

Publication Date: 20260512
Application Date: 20260413

Claims (10)

1. The LED driving circuit is characterized by comprising an error amplifying module, a switch module and an output resistor module, wherein the output resistor module comprises n switch units and n resistor units, a first input end of the error amplifying module is used for receiving first voltage, a second input end of the error amplifying module is respectively connected with a first end of the switch module and a first end of the n resistor units, the voltage on the second input end of the error amplifying module is second voltage, an output end of the error amplifying module is connected with a control end of the switch module, a second end of the switch module is used for being connected with a negative electrode of an LED lamp, a second end of the n resistor units is connected with the first ends of the n switch units in a one-to-one correspondence manner, and second ends of the n switch units are grounded, wherein the total output impedance of the output resistor module is kept constant, and n is a natural number larger than 0; The error amplification module is used for outputting control signals according to the first voltage and the second voltage, the switch module is used for conducting according to the control signals to enable the output resistor module to be connected with the negative electrode of the LED lamp in a conducting mode, and the output resistor module is used for determining the conducting number of the switch units according to the output current of the LED lamp to enable the corresponding number of resistor units to be connected with the ground in a conducting mode.
2. The LED driving circuit according to claim 1, wherein the resistor unit includes a first resistor having a first end connected to the second input terminal of the error amplifying module and the first end of the switching module, respectively, and a second end connected to the first end of the switching unit.
3. The LED driving circuit according to claim 1, wherein the switching unit includes a first switch having a first end connected to a second end of the resistance unit, and a second end of the first switch is grounded.
4. The LED driving circuit of claim 1, wherein the error amplifying module comprises a first error amplifier, the switching module comprises a first switching tube, a first input terminal of the first error amplifier is used for receiving a first voltage, a second input terminal of the first error amplifier is respectively connected with a source electrode of the first switching tube and first ends of n resistance units, a voltage on a second input terminal of the first error amplifier is a second voltage, an output terminal of the first error amplifier is connected with a gate electrode of the first switching tube, and a drain electrode of the first switching tube is used for being connected with a cathode electrode of the LED lamp.
5. The LED driving circuit according to claim 1, wherein n switch units are encoded with n-bit thermometers, and the resistances of n resistor units are all the same.
6. An LED driving system, comprising a plurality of LED lamps and a plurality of LED driving circuits according to any one of claims 1 to 5, wherein the second ends of the switch modules in the plurality of LED driving circuits are connected to the cathodes of the plurality of LED lamps in one-to-one correspondence, and the anodes of the plurality of LED lamps all receive a first power supply voltage.
7. The LED driving system of claim 6, further comprising a plurality of digital-to-analog conversion circuits connected in one-to-one correspondence with the first input terminals of the error amplification modules in the plurality of LED driving circuits; the digital-to-analog conversion circuit is used for outputting analog voltage according to the reference voltage and m-bit input gears, and filtering the analog voltage to obtain first voltage, wherein m is a natural number greater than 0.
8. The LED driving system according to claim 7, wherein the digital-to-analog conversion circuit comprises a digital-to-analog conversion unit and a filter unit, the filter unit being connected to the digital-to-analog conversion unit and the first input terminal of the error amplification module, respectively; The digital-to-analog conversion unit is used for outputting analog voltage according to the reference voltage and the m-bit input gear, and the filtering unit is used for filtering the analog voltage to obtain first voltage.
9. The LED driving system of claim 6, further comprising a voltage generation circuit connected to the first input of the error amplification module of the plurality of LED driving circuits, respectively; the voltage generation circuit is used for outputting analog voltage according to the reference voltage and m-bit input gears, filtering the analog voltage to obtain filtered analog voltage, and outputting a plurality of first voltages according to the filtered analog voltage, wherein m is a natural number larger than 0.
10. The LED driving system according to claim 9, wherein the voltage generating circuit comprises a digital-to-analog converter, a second resistor, a first capacitor, a second error amplifier, a second switching tube, a third resistor, and a plurality of current mirror branches, each current mirror branch comprising a fourth switching tube and a fourth resistor, a first end of the second resistor being connected to the digital-to-analog converter, a second end of the second resistor being connected to a first end of the first capacitor and a first input of the second error amplifier, a second input of the second error amplifier being connected to a source of the second switching tube and a first end of the third resistor, an output of the second error amplifier being connected to a gate of the second switching tube, a drain of the second switching tube being connected to a drain of the third switching tube, a gate of the third switching tube and a gate of the plurality of fourth switching tubes, a source of the third switching tube and a first input of the plurality of fourth switching tubes being connected to a source of the fourth switching tubes, a voltage receiving the fourth switching tube and a drain of the fourth switching tube being connected to the first end of the fourth switching tube, and a drain of the fourth switching tube being connected to the first resistor, respectively.

Description

LED driving circuit and LED driving system Technical Field The application belongs to the technical field of electronic circuits, and particularly relates to an LED driving circuit and an LED driving system. Background The LED (LIGHT EMITTING Diode) has the advantages of environmental protection, energy saving, high efficiency, long service life, etc., and is widely used in backlight display of electronic products such as mobile phones, notebook computers, etc. In order to ensure normal light emission and basic functions of a backlight display screen, an LED driving circuit for providing stable current is an essential core component. The LED driving circuit provides stable and adaptive current and voltage for the LEDs, and is a special circuit for guaranteeing the constant brightness and long service life of the LEDs. The core function is to restrain the current greatly changed caused by the tiny waveform of the voltage and realize the additional functions such as dimming. The current precision is a core performance index of the LED driving circuit and directly determines the consistency and stability of the brightness of the LED, but the current LED driving circuit has the problem of larger current error, which can cause poor consistency of the brightness of a display product, degradation of visual effect and shortened service life of the LED. Disclosure of Invention The embodiment of the application provides an LED driving circuit and an LED driving system, which can solve the problem of large current error of the traditional LED driving circuit. In a first aspect, an embodiment of the present application provides an LED driving circuit, including an error amplifying module, a switch module, and an output resistor module, where the output resistor module includes n switch units and n resistor units, a first input end of the error amplifying module is configured to receive a first voltage, a second input end of the error amplifying module is connected to the first end of the switch module and the first end of the n resistor units, a voltage on the second input end of the error amplifying module is a second voltage, an output end of the error amplifying module is connected to a control end of the switch module, a second end of the switch module is configured to be connected to a negative electrode of an LED lamp, a second end of the n resistor units is connected to the first ends of the n switch units in a one-to-one correspondence manner, and second ends of the n switch units are all grounded, where a total output impedance of the output resistor module is kept constant, and n is a natural number greater than 0; The error amplification module is used for outputting control signals according to the first voltage and the second voltage, the switch module is used for conducting according to the control signals to enable the output resistor module to be connected with the negative electrode of the LED lamp in a conducting mode, and the output resistor module is used for determining the conducting number of the switch units according to the output current of the LED lamp to enable the corresponding number of resistor units to be connected with the ground in a conducting mode. In a possible implementation manner of the first aspect, the resistor unit includes a first resistor, a first end of the first resistor is connected to the second input end of the error amplifying module and the first end of the switching module, and a second end of the first resistor is connected to the first end of the switching unit. In a possible implementation manner of the first aspect, the switching unit includes a first switch, a first end of the first switch is connected to a second end of the resistor unit, and a second end of the first switch is grounded. In one possible implementation manner of the first aspect, the error amplifying module includes a first error amplifier, the switching module includes a first switching tube, a first input end of the first error amplifier is used for receiving a first voltage, a second input end of the first error amplifier is respectively connected with a source electrode of the first switching tube and first ends of n resistance units, a voltage on the second input end of the first error amplifier is a second voltage, an output end of the first error amplifier is connected with a gate electrode of the first switching tube, and a drain electrode of the first switching tube is used for being connected with a cathode electrode of the LED lamp. In a possible implementation manner of the first aspect, the n switch units are encoded by n-bit thermometers, and resistance values of the n resistor units are all the same. In a second aspect, an embodiment of the present application provides an LED driving system, including a plurality of LED lamps and the LED driving circuit according to any one of the first aspect, wherein second ends of switch modules in the plurality of LED driving circuits are conn