CN213462406U

CN213462406U - Analog dimming circuit for LED driving chip

Info

Publication number: CN213462406U
Application number: CN202022720799.5U
Authority: CN
Inventors: 郑泽鹏
Original assignee: Shenzhen Ua Microamp Integration Technology Co ltd
Current assignee: Shenzhen Ua Microamp Integration Technology Co ltd
Priority date: 2020-11-20
Filing date: 2020-11-20
Publication date: 2021-06-15
Anticipated expiration: 2030-11-20

Abstract

The utility model belongs to the technical field of electronic integration, and discloses an analog dimming circuit for an LED driving chip, which comprises a dimming control module, a switch control module, a driving IC chip and an LED control module; one end of the dimming control module is externally connected with a control voltage from an analog dimmer, the other end of the dimming control module is electrically connected with one end of the switch control module, the other end of the switch control module is electrically connected with one end of the drive IC chip, and the other end of the drive IC chip is electrically connected with the LED control module; the first control voltage or the second control voltage is converted into reference voltage through the dimming control module, the switch control module provides a driving signal for the driving IC chip according to the reference voltage, and the driving IC chip provides control voltage for the LED control module so as to drive the LED control module to conduct and work. The utility model discloses can support the simulation light modulator of wideer scope, satisfy the simulation demand of adjusting luminance on a wider scale.

Description

Analog dimming circuit for LED driving chip

Technical Field

The utility model belongs to the technical field of the electron is integrated, concretely relates to simulation dimmer circuit for LED driver chip.

Background

The LED has the advantages of high luminous efficiency, long service life and the like, thereby being widely applied. The LED can be dimmed, so that the energy-saving characteristic of the LED can be further exerted, and the service life of the LED is prolonged.

In conventional analog dimming, the current of the LED is usually changed by adjusting the resistance of the LED series resistor, and dimming is implemented by using a voltage division principle. With the invention of the novel non-pure resistance LED drive, the dimming can not be realized by simply changing the resistance value of the resistor, and the analog dimming mechanism is changed accordingly. However, even if the dimming mechanism is changed, the control mode of the analog dimming is not changed, and the LED output equivalent current is changed according to the magnitude of the input analog signal, so as to realize the dimming function.

In the process of implementing the prior art, the inventor finds that at least the following problems exist in the prior art:

at present, an analog dimming circuit for adjusting an LED lamp current generally adjusts the brightness of the LED lamp through an analog signal provided by an analog dimmer, but the range of the analog signal supported by the existing analog dimming circuit for adjusting the LED lamp current is limited, and the requirement of analog dimming in a wider range cannot be met.

Therefore, there is a need for an analog dimming circuit for an LED driving chip capable of supporting a wide range of analog dimmers.

SUMMERY OF THE UTILITY MODEL

The utility model discloses aim at least solve one of above-mentioned technical problem to a certain extent.

Therefore, the utility model aims to provide an analog dimming circuit for LED driver chip can support the wide range analog dimmer to satisfy wider analog dimming demand.

The utility model discloses the technical scheme who adopts does:

an analog dimming circuit for an LED driving chip comprises a dimming control module, a switch control module, a driving IC chip and an LED control module;

the input end of the dimming control module is respectively externally connected with a first control voltage and a second control voltage, the output end of the dimming control module is electrically connected with one end of the switch control module, the other end of the switch control module is electrically connected with one end of the drive IC chip, and the other end of the drive IC chip is electrically connected with the LED control module;

the dimming control module selects lower voltage in the first control voltage and the second control voltage and converts the lower voltage into reference voltage, the switch control module provides a driving signal for the driving IC chip according to the reference voltage, and the driving IC chip provides control voltage for the LED control module.

Furthermore, the dimming control module comprises a voltage selection circuit and a voltage output control circuit, the input end of the voltage selection circuit is respectively externally connected with a first control voltage and a second control voltage, the output end of the voltage selection circuit is electrically connected with one end of the voltage output control circuit, and the other end of the voltage output control circuit is electrically connected with the switch control module and outputs a reference voltage.

Further, the voltage selection circuit comprises a first NMOS tube and a second NMOS tube, a drain electrode of the first NMOS tube and a gate electrode of the second NMOS tube are both externally connected with a first control voltage, a gate electrode of the first NMOS tube and a drain electrode of the second NMOS tube are both externally connected with a second control voltage, a source electrode of the first NMOS tube is electrically connected with a source electrode of the second NMOS tube, and a joint point of the source electrode of the first NMOS tube and the source electrode of the second NMOS tube is electrically connected with the voltage output control circuit.

Furthermore, the voltage output control circuit comprises a first voltage comparator, a third NMOS transistor, a PMOS transistor, a first resistor and a second resistor; the non-inverting input end of the first voltage comparator is electrically connected with a joint point of a source electrode of the first NMOS tube and a source electrode of the second NMOS tube, the inverting input end of the first voltage comparator is electrically connected with a source electrode of the third NMOS tube, the output end of the first voltage comparator is electrically connected with a joint point of a source electrode and a grid electrode of the third NMOS tube, the source electrode of the PMOS tube is connected with an internal power supply, the grid electrode of the PMOS tube and the drain electrode of the PMOS tube are electrically connected with a drain electrode of the third NMOS tube, one end of the first resistor is electrically connected with the source electrode of the third NMOS tube through the second resistor, the other end of the first resistor is grounded, and the joint point of the first resistor and the second resistor is electrically connected with the switch control module and outputs reference voltage.

Further, the switch control module comprises a second voltage comparator, an oscillator, a first nand gate and a second nand gate; the non-inverting input end of the second voltage comparator is electrically connected with the joint of the first resistor and the second resistor, the inverting input end of the second voltage comparator is connected with the CS pin of the drive IC chip, the output end of the second voltage comparator is electrically connected with one input end of a second NAND gate, the other input end of the second NAND gate is electrically connected with the output end of the first NAND gate, one input end of the first NAND gate is electrically connected with the oscillator, the other input end of the first NAND gate is electrically connected with the output end of the second NAND gate, and the output end of the second NAND gate is also electrically connected with the drive IC chip.

Further, the LED control module comprises a third resistor, a fourth resistor, a first capacitor, a diode, a first light emitting diode, a second light emitting diode, an inductor and a fourth NMOS tube; one end of the third resistor and one end of the first capacitor are both electrically connected with a VDD pin of the driving chip IC, the other end of the third resistor is connected with the anode of an input power supply, the other end of the first capacitor is electrically connected with a pin of the driving chip IC and then grounded, the GATE pin of the driving chip IC is electrically connected with the GATE of the fourth NMOS tube, the anode of the diode and one end of the inductor are both electrically connected with the drain of the fourth NMOS tube, the cathode of the diode is connected with the anode of the input power supply, the other end of the inductor is connected with the cathode of the second light-emitting diode, the anode of the second light-emitting diode is electrically connected with the cathode of the first light-emitting diode, the anode of the first light-emitting diode is connected with the anode of an input power supply +, and the pin of the driving chip IC and the source electrode of the fourth NMOS tube are electrically connected with one end of a fourth resistor, and the other end of the fourth resistor is grounded.

Furthermore, the control module further comprises a second capacitor, one end of the second capacitor is electrically connected with the anode of the input power supply, and the other end of the second capacitor is electrically connected with the cathode of the input power supply and then grounded.

The utility model has the advantages that:

the utility model provides a simulation light modulation circuit for LED driver chip can support the simulation light modulator of wideer scope to satisfy wider simulation demand of adjusting luminance. The utility model discloses a dimming control module can select in the analog signal of simulation light modulator input and the analog signal of settlement, realizes the purpose of nimble regulation control voltage's threshold value, thereby improves the utility model discloses a compatibility satisfies wider simulation demand of adjusting luminance.

Other advantageous effects of the present invention will be described in detail in the detailed description of the invention.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.

Fig. 1 is a schematic circuit diagram of the dimming control module of the present invention.

Fig. 2 is a schematic structural diagram of the present invention with the LED control module removed.

Fig. 3 is a schematic circuit diagram of the LED control module of the present invention.

Fig. 4 is a graph showing a variation relationship between the reference voltage and the second control voltage according to the present invention.

Fig. 5 is a second control voltage and LED current variation waveform diagram of the present invention.

In the figure: u1-drive IC chip; u2 — first voltage comparator; u3 — second voltage comparator; u4-first nand gate; u5-second nand gate; VCC-internal power supply; vin + -input power supply positive; vin- -input power supply negative; VDIM _ H — first control voltage; DIM-second control voltage; an OSC-oscillator; ref — reference voltage; m1-first NMOS transistor; m2-second NMOS tube; m3-third NMOS tube; m4-fourth NMOS tube; M5-PMOS tube; c1 — first capacitance; c2 — second capacitance; r1 — first resistance; r2 — second resistance; r3 — third resistance; r4-fourth resistor; l1-inductance; LED 1-first light emitting diode; LED 2-second light emitting diode.

Detailed Description

The technical solution provided by the present invention will be described in detail by way of embodiments with reference to the accompanying drawings. It should be noted that the description of the embodiments is provided to help understanding of the present invention, but the present invention is not limited thereto.

In some instances, some embodiments are not described or not in detail, as they are conventional or customary in the art.

Furthermore, the technical features described herein, or the steps of all methods or processes disclosed, may be combined in any suitable manner in one or more embodiments, in addition to the mutually exclusive features and/or steps. It will be readily appreciated by those of skill in the art that the order of the steps or operations of the methods associated with the embodiments provided herein may be varied. Any order in the drawings and examples is for illustrative purposes only and does not imply that a certain order is required unless explicitly stated to be required.

The numbering of the components as such, e.g., "first", "second", etc., is used herein only to distinguish the objects as described, and does not have any sequential or technical meaning. The terms "connected" and "coupled" when used in this application, encompass both direct and indirect connections (and couplings) where appropriate and where not necessary contradictory.

Example 1

As shown in fig. 1 to 5, the present embodiment provides an analog dimming circuit for an LED driving chip, which includes a dimming control module, a switch control module, a driving IC chip U1 and an LED control module; the input end of the dimming control module is respectively externally connected with a first control voltage VDIM _ H and a second control voltage DIM, the output end of the dimming control module is electrically connected with one end of the switch control module, the other end of the switch control module is electrically connected with one end of a driving IC chip U1, and the other end of the driving IC chip U1 is electrically connected with the LED control module; the dimming control module selects a lower voltage of the first control voltage VDIM _ H and the second control voltage DIM and converts it into a reference voltage ref; the switch control module provides a driving signal for the driving IC chip U1 according to the reference voltage ref, and the driving IC chip U1 provides a control voltage for the LED control module.

In this embodiment, the first control voltage VDIM _ H is a set voltage, the second control voltage DIM is an analog voltage signal from an analog dimmer, the dimming control module can select two voltage signals, convert the selected voltage into a reference voltage ref, the switch control module outputs a digital control signal to the driving IC chip U1 according to the reference voltage ref, and the driving IC chip U1 outputs a corresponding analog control signal for controlling the LED control module to turn on or off. In this embodiment, the first control voltage VDIM _ H is changed to satisfy the input of the second control voltage DIM in a wider range, and the dimming control module can flexibly adjust the threshold of the control voltage to satisfy the analog dimming requirement in a wider range.

Furthermore, the dimming control module comprises a voltage selection circuit and a voltage output control circuit, one end of the voltage selection circuit is respectively externally connected with the first control voltage VDIM _ H and the second control voltage DIM, the other end of the voltage selection circuit is electrically connected with one end of the voltage output control circuit, and the other end of the voltage output control circuit is electrically connected with the switch control module and outputs the reference voltage ref. The voltage selection circuit is used for selecting the lower voltage of the first control voltage VDIM _ H and the second control voltage DIM, and the selected voltage is converted into the reference voltage ref through the voltage output control circuit.

Further, the voltage selection circuit comprises a first NMOS transistor M1 and a second NMOS transistor M2, a drain of the first NMOS transistor M1 and a gate of the second NMOS transistor M2 are both externally connected with a first control voltage VDIM _ H, a gate of the first NMOS transistor M1 and a drain of the second NMOS transistor M2 are both externally connected with a second control voltage DIM, a source of the first NMOS transistor M1 is electrically connected with a source of the second NMOS transistor M2, and a junction point of the source of the first NMOS transistor M1 and the source of the second NMOS transistor M2 is electrically connected with the voltage output control circuit. Specifically, when VDIM _ H < DIM, the gate of the first NMOS transistor M1 is turned on by the second control voltage DIM providing a forward bias, and the common terminal of the first NMOS transistor M1 and the second NMOS transistor M2 outputs the first control voltage VDIM _ H; when VDIM _ H > DIM, the gate of the second NMOS transistor M2 is turned on by the first control voltage VDIM _ H with a forward bias, and the common terminal of the first NMOS transistor M1 and the second NMOS transistor M2 outputs the second control voltage DIM.

Further, the voltage output control circuit comprises a first voltage comparator U2, a third NMOS transistor M3, a PMOS transistor M5, a first resistor R1 and a second resistor R2; the non-inverting input end of the first voltage comparator U2 is electrically connected with a junction point of a source electrode of the first NMOS tube M1 and a source electrode of the second NMOS tube M2, the inverting input end of the first voltage comparator U2 is electrically connected with a source electrode of the third NMOS tube M3, the output end of the first voltage comparator U2 is electrically connected with a junction point of a source electrode and a grid electrode of the third NMOS tube M3, the source electrode of the PMOS tube M5 is connected with an internal power supply VCC, the grid electrode of the PMOS tube M5 and the drain electrode of the PMOS tube M5 are both electrically connected with a drain electrode of the third NMOS tube M3, the first resistor R1 is electrically connected with a source electrode of the third NMOS tube M3 through a second resistor R2, the other end of the first resistor R2 is grounded, and the junction point of the first resistor R1 and the second resistor R2 is electrically connected with the switch control module and outputs a reference voltage ref. Specifically, the first voltage comparator U2 and the third NMOS transistor M3 form a voltage follower, the gate of the third NMOS transistor M3 is turned on by the output terminal of the first voltage comparator U2 providing a forward bias, the output of the voltage follower is the output voltage of the voltage selection circuit, the output voltage is divided by the first resistor R1 and the second resistor R2, and finally the reference voltage ref is output at the junction point of the first resistor R1 and the second resistor R2. In the present embodiment, the resistances of the first resistor R1 and the second resistor R2 have the following relationship: R2/R1 is (N-1)/1, where N is a proportionality coefficient, and according to ohm's law, the final reference voltage ref is min { DIM, VDIM _ H } × R1/(R1+ R2) ═ min { DIM, VDIM _ H }/N, and the proportionality coefficient N therein can be flexibly adjusted according to actual needs, and as one of the preferred solutions, when the set first control voltage VDIM _ H is 3V, it is preferable that N is 15 so that the ref maximum value is 0.2V.

Further, the switch control module includes a second voltage comparator U3, an oscillator OSC, a first nand gate U4, a second nand gate U5; the non-inverting input terminal of the second voltage comparator U3 is electrically connected to the junction of the first resistor R1 and the second resistor R2, the inverting input terminal of the second voltage comparator U3 is connected to the CS pin of the driver IC chip U1, the output terminal of the second voltage comparator U3 is electrically connected to one of the input terminals of the second nand gate U5, the other input terminal of the second nand gate U5 is electrically connected to the output terminal of the first nand gate U4, one input terminal of the first nand gate U4 is electrically connected to the oscillator OSC, the other input terminal of the first nand gate U4 is electrically connected to the output terminal of the second nand gate U5, and the output terminal of the second nand gate U5 is also electrically connected to the driver IC chip. Specifically, the first nand gate U4 and the second nand gate U5 constitute an RS flip-flop, the oscillator OSC generates a pulse clock, and at the same time, at the input terminal of the second voltage comparator U3, the current detection pin CS of the driving IC chip U1 is compared with a reference voltage ref, the output terminal of the second voltage comparator U3 and the oscillator OSC together provide a control signal for the driving IC chip U1 through the RS flip-flop, specifically, when the CS pin voltage is greater than the reference voltage ref, the driving IC chip U1 is controlled to pull down the control voltage in the LED control module, so that the LED control module is turned off and off, then when the next pulse signal of the oscillator ref arrives, the driving IC chip U1 is controlled to drive the control voltage in the LED control module, so that the LED control module is turned on, and after the LED control module is turned on, the CS pin voltage linearly rises to the reference voltage OSC, so that the operation is periodic.

Further, the LED control module includes a third resistor R3, a fourth resistor R4, a first capacitor C1, a diode D1, a first light emitting diode LED1, a second light emitting diode LED2, an inductor L1, and a fourth NMOS transistor M4; one end of the third resistor R3 and one end of the first capacitor C1 are both electrically connected to the VDD pin of the driver IC chip U1, the other end of the third resistor R3 is electrically connected to the input power supply positive electrode Vin +, the other end of the first capacitor C1 is electrically connected to the GND pin of the driver IC chip U1 and then grounded, the GATE pin of the driver IC chip U1 is electrically connected to the GATE of the fourth NMOS transistor M4, the anode of the diode D1 and one end of the inductor L1 are both electrically connected to the drain of the fourth NMOS transistor M4, the cathode of the diode D1 is electrically connected to the input power supply positive electrode Vin +, the other end of the inductor L1 is electrically connected to the cathode of the second light emitting diode LED2, the anode of the second light emitting diode LED2 is electrically connected to the cathode of the first light emitting diode LED1, the anode of the first light emitting diode LED1 is electrically connected to the input power supply positive electrode Vin +, the CS pin of the driver IC chip U1 and the source of the fourth NMOS transistor M4 are both electrically connected to one end of the fourth resistor R. In this embodiment, the GATE pin of the driving IC chip U1 is electrically connected to the GATE of the fourth NMOS transistor M4, when the voltage at the CS pin is greater than the reference voltage ref in each switching period, the voltage at the GATE pin of the driving IC chip U1 rises to forward bias the GATE of the fourth NMOS transistor M4 to be on, the first LED1 and the second LED2 are both turned on by the external power source, when the voltage at the GATE pin of the driving IC chip U1 is pulled down, the fourth NMOS transistor M4 is turned off to be in an off state, and the first LED1 and the second LED2 are turned off to wait for the next control signal.

Furthermore, the LED control module further includes a second capacitor C2, one end of the second capacitor C2 is electrically connected to the positive electrode Vin + of the input power, and the other end of the second capacitor C2 is electrically connected to the negative electrode Vin-of the input power and then grounded, so that noise and ac components of the input power can be filtered out, the input dc voltage is more stable, and accordingly, smoother operating currents are provided for the first light emitting diode LED1 and the second light emitting diode LED 2.

The embodiments described above are merely illustrative, and may or may not be physically separate, if referring to units illustrated as separate components; if reference is made to a component displayed as a unit, it may or may not be a physical unit, and may be located in one place or distributed over a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment. One of ordinary skill in the art can understand and implement it without inventive effort.

The above embodiments are only used to illustrate the technical solution of the present invention, and not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it should be understood by those skilled in the art that: modifications of the technical solutions described in the embodiments or equivalent replacements of some technical features may still be made. Such modifications and substitutions do not depart from the spirit and scope of the present invention in its corresponding aspects.

The present invention is not limited to the above-mentioned alternative embodiments, and various other products can be obtained by anyone under the teaching of the present invention. The above detailed description should not be taken as limiting the scope of the invention, which is defined in the following claims, and which can be used to interpret the claims.

Claims

1. An analog dimming circuit for an LED driver chip, comprising: the LED driving circuit comprises a dimming control module, a switch control module, a driving IC chip (U1) and an LED control module;

the input end of the dimming control module is respectively externally connected with a first control voltage (VDIM _ H) and a second control voltage (DIM), the output end of the dimming control module is electrically connected with one end of the switch control module, the other end of the switch control module is electrically connected with one end of a driving IC chip (U1), and the other end of the driving IC chip (U1) is electrically connected with the LED control module;

the dimming control module selects a lower voltage of the first control voltage (VDIM _ H) and the second control voltage (DIM) and converts it to a reference voltage (ref); the switch control module provides a driving signal for a driving IC chip (U1) according to a reference voltage (ref), and the driving IC chip (U1) provides a control voltage for the LED control module.

2. The analog dimming circuit for an LED driving chip according to claim 1, wherein: the dimming control module comprises a voltage selection circuit and a voltage output control circuit, wherein the input end of the voltage selection circuit is respectively used for being externally connected with a first control voltage (VDIM _ H) and a second control voltage (DIM), the output end of the voltage selection circuit is electrically connected with one end of the voltage output control circuit, and the other end of the voltage output control circuit is electrically connected with the switch control module and outputs a reference voltage (ref).

3. An analog dimming circuit for an LED driving chip according to claim 2, wherein: the voltage selection circuit comprises a first NMOS tube (M1) and a second NMOS tube (M2), wherein the drain electrode of the first NMOS tube (M1) and the gate electrode of the second NMOS tube (M2) are both externally connected with a first control voltage (VDIM _ H), the gate electrode of the first NMOS tube (M1) and the drain electrode of the second NMOS tube (M2) are both externally connected with a second control voltage (DIM), the source electrode of the first NMOS tube (M1) is electrically connected with the source electrode of the second NMOS tube (M2), and the junction point of the source electrode of the first NMOS tube (M1) and the source electrode of the second NMOS tube (M2) is electrically connected with the voltage output control circuit.

4. An analog dimming circuit for an LED driving chip according to claim 2, wherein: the voltage output control circuit comprises a first voltage comparator (U2), a third NMOS transistor (M3), a PMOS transistor (M5), a first resistor (R1) and a second resistor (R2); the non-inverting input end of the first voltage comparator (U2) is electrically connected with the combination point of the source electrode of the first NMOS tube (M1) and the source electrode of the second NMOS tube (M2), the inverting input end of the first voltage comparator (U2) is electrically connected with the source electrode of the third NMOS tube (M3), the output end of the first voltage comparator (U2) is electrically connected with the grid electrode of the third NMOS tube (M3), the source electrode of the PMOS tube (M5) is electrically connected with an internal power supply (VCC), the grid electrode of the PMOS tube (M5) and the drain electrode of the PMOS tube (M5) are both electrically connected with the drain electrode of the third NMOS tube (M3), one end of the first resistor (R1) is electrically connected with the source electrode of the third NMOS transistor (M3) through a second resistor (R2), the other end of the first resistor (R1) is grounded, and the joint point of the first resistor (R1) and the second resistor (R2) is electrically connected with the switch control module and outputs a reference voltage (ref).

5. The analog dimming circuit for an LED driving chip according to claim 4, wherein: the switch control module comprises a second voltage comparator (U3), an Oscillator (OSC), a first NAND gate (U4) and a second NAND gate (U5); the non-inverting input end of the second voltage comparator (U3) is electrically connected with the joint of the first resistor (R1) and the second resistor (R2), the inverting input end of the second voltage comparator (U3) is electrically connected with the CS pin of the driving IC chip (U1), the output end of the second voltage comparator (U3) is electrically connected with one input end of a second NAND gate (U5), the other input end of the second NAND gate (U5) is electrically connected with the output end of a first NAND gate (U4), one input end of the first NAND gate (U4) is electrically connected with the Oscillator (OSC), the other input end of the first NAND gate (U4) is electrically connected with the output end of a second NAND gate (U5), and the output end of the second NAND gate (U5) is also electrically connected with the driving IC chip (U1).

6. The analog dimming circuit for an LED driving chip according to claim 1, wherein: the LED control module comprises a third resistor (R3), a fourth resistor (R4), a first capacitor (C1), a diode (D1), a first light-emitting diode (LED1), a second light-emitting diode (LED2), an inductor (L1) and a fourth NMOS tube (M4); one end of the third resistor (R3) and one end of the first capacitor (C1) are both electrically connected with the VDD pin of the driver IC chip (U1), the other end of the third resistor (R3) is connected with the input power positive electrode (Vin +), the other end of the first capacitor (C1) is electrically connected with the GND pin of the driver IC chip (U1) and then grounded, the GATE pin of the driver IC chip (U1) is electrically connected with the GATE of the fourth NMOS tube (M4), the anode of the diode (D1) and one end of the inductor (L1) are both electrically connected with the drain of the fourth NMOS tube (M4 +), the cathode of the diode (D1) is connected with the input power positive electrode (Vin +), the other end of the inductor (L1) is electrically connected with the cathode of the second light emitting diode (LED2), the anode of the second light emitting diode (LED2) is connected with the cathode of the first light emitting diode (LED1), the anode of the first light emitting diode (1) is connected with the input power positive electrode (Vin +), the CS pin of the driving IC chip (U1) and the source electrode of the fourth NMOS tube (M4) are electrically connected with one end of a fourth resistor (R4), and the other end of the fourth resistor (R4) is grounded.

7. The analog dimming circuit for an LED driving chip according to claim 6, wherein: the LED control module further comprises a second capacitor (C2), one end of the second capacitor (C2) is electrically connected with the positive electrode (Vin +) of the input power supply, and the other end of the second capacitor (C2) is electrically connected with the negative electrode (Vin-) of the input power supply and then grounded.