An AC square wave dimming circuit

Abstract

The present invention provides an AC square wave dimming circuit, comprising: a central processing unit (CPU), an SPI to DAC circuit, a transistor-controlled switch circuit, an operational inverse phase circuit, a switch chip circuit, a power supply circuit, and a power operational amplifier. The CPU is connected to the SPI to DAC circuit via its SPI port, the transistor-controlled switch circuit is connected to the CPU via its PWM interface, the operational inverse phase circuit is connected to the SPI to DAC circuit and the switch chip circuit, respectively, the switch chip circuit is connected to the power operational amplifier, and the transistor-controlled switch circuit, the switch chip circuit, and the power operational amplifier are all connected to the power supply circuit. The CPU is configured to change the duty cycle of the power supply, and the SPI to DAC circuit is configured to provide the CPU with four dimming outputs. By using the AC square wave dimming circuit, the transmittance of industrial dimming glass can be controlled.

Description

Technical Field

[0001] The present invention relates to the technical field of dimming circuits, and in particular to an AC square wave dimming circuit. Background Art

[0002] As demand for energy-efficient and intelligent lighting solutions continues to grow, AC square-wave dimming technology is expected to continue to expand its market share, particularly in industrial dimming glass projects. This technology will become more advanced, offering additional features such as dynamic dimming and integration with other systems. The reduced hardware cost, smaller size, and stable performance of this solution make this technology more accessible and affordable.

[0003] However, the existing AC square wave dimming is not suitable for industrial dimming glass projects. Summary of the Invention

[0004] In view of this, the embodiments of this specification provide an AC square wave dimming circuit to achieve the purpose of regulating the transmittance of industrial dimming glass.

[0005] The embodiments of this specification provide the following technical solutions:

[0006] An AC square wave dimming circuit, comprising:

[0007] Central processing unit, SPI to DAC circuit, transistor control switch circuit, operational inverse phase circuit, switch chip circuit, power supply circuit, power operational amplifier;

[0008] The central processing unit is connected to the SPI to DAC circuit via the SPI port of the central processing unit, the transistor control switch circuit is connected to the central processing unit via the PWM interface of the central processing unit, the operational inverse phase circuit is connected to the SPI to DAC circuit and the switch chip circuit respectively, the switch chip circuit is connected to the power operational amplifier, and the transistor control switch circuit, the switch chip circuit and the power operational amplifier are all connected to the power supply circuit;

[0009] The central processing unit is used to change the duty cycle of the power supply, the SPI to DAC circuit is used to provide 4-channel dimming outputs for the central processing unit, the transistor control switch circuit is used to increase the voltage range to 0-5V, the switch chip circuit is used to output a square wave signal to the power operational amplifier, the power operational amplifier is used to adjust the output voltage and output current and output them through the external interface, and the power supply circuit is used to provide power for the transistor control switch circuit, the switch chip circuit and the power operational amplifier.

[0010] Further, the SPI to DAC circuit includes a digital to analog converter;

[0011] The digital-to-analog converter includes VDD pin, VREFL pin, VREFH pin, VSS pin, CS pin, CLK pin, SDI pin, register reset pin RESETSEL, chip reset pin RESET, and chip latch status pin LOADDACS;

[0012] The VDD pin is connected to the 5V reference voltage, the VSS pin is connected to the -5V reference voltage, the CS pin, CLK pin, and SDI pin are respectively connected in series with the first resistor R577, the second resistor R578, and the third resistor R579, and then connected to the SPI1_CS pin, SPI1_CLK pin, and SPI1_DSI pin of the central processing unit. The VREFL pin is connected to the 2.5V reference voltage, the VREFH pin is connected to the -2.5V reference voltage, the register reset pin RESETSEL, the chip reset pin RESET, and the chip latch status pin LOADDACS are respectively connected to the GPIO pins of the central processing unit.

[0013] Furthermore, the operational in-phase opposite-phase circuit includes:

[0014] DAC chip reference voltage circuit, first operational amplifier and second operational amplifier;

[0015] The output voltage of the DAC chip reference voltage circuit is connected to the +IN pin of the first operational amplifier through a fourth resistor R504 connected in series. The -IN pin of the first operational amplifier is connected to the fifth resistor R500 and then to ground. It is connected to the OUT pin of the first operational amplifier after connecting to the sixth resistor R501 and the first capacitor C501. The OUT pin of the first operational amplifier is connected to the seventh resistor R503 and then to the output control switch SA1. The voltage of the output control switch SA1 is connected in series with the eighth resistor R516 and then to the -IN pin of the second operational amplifier and is connected to the OUT pin of the second operational amplifier after connecting to the ninth resistor R512 and the second capacitor C505. The +IN pin of the second operational amplifier is connected to the tenth resistor R514 and to ground. The OUT pin of the second operational amplifier is connected to the eleventh resistor R513 and the third capacitor C519. The V-0 pin, V-1 pin, and V-2 pin of the first operational amplifier and the second operational amplifier are all connected to a -24V voltage. The V+ pins of the first operational amplifier and the second operational amplifier are connected to a +24V voltage. The FLAG pins of the first operational amplifier and the second operational amplifier are grounded.

[0016] Furthermore, the switch chip circuit includes:

[0017] S1A pin, S1B pin, D1 pin, D2 pin, VDD pin, VSS pin, PAD pin;

[0018] Connect the VDD pin to +15V, and the VSS and PAD pins to -15V.

[0019] Pins S1A, S1B, and D1 form a 1-way switch;

[0020] The output voltage of the D1 and D2 pins is a square wave signal with a ±10V voltage, a 60HZ frequency, and a 50% duty cycle.

[0021] Furthermore, the power operational amplifier includes:

[0022] Output connector J5_A2, VIN- pin, VO pin and +IN pin;

[0023] The switch chip is connected to the VIN- pin through the twelfth resistor R634, and is connected to the VO pin through the thirteenth resistor R635 and the fourth capacitor C667. The +IN pin is grounded through the fourteenth resistor R706, and the VO pin is connected to the 1PIN pin of the output connector J5_A2 through the fifteenth resistor R640, and the VO pin is grounded through the fifth capacitor C600.

[0024] Furthermore, the power supply circuit includes:

[0025] a first voltage conversion circuit, a second voltage conversion circuit, and a third voltage conversion circuit;

[0026] The first voltage conversion circuit is used to convert 12V to 5V;

[0027] The second voltage conversion circuit is used to convert 5V into ±15V;

[0028] The third voltage conversion circuit is used to convert 12V to ±24V.

[0029] Furthermore, the transistor control switch circuit includes:

[0030] triode;

[0031] The base of the transistor is connected to the PWM port of the central processing unit through the sixteenth resistor R627;

[0032] The collector of the transistor is connected to the IN1 port of the switch chip circuit;

[0033] The emitter of the transistor is grounded after passing through the seventeenth resistor R626 and the eighteenth resistor R649.

[0034] Compared with the prior art, the at least one technical solution adopted in the embodiments of this specification can achieve the following beneficial effects:

[0035] The purpose of regulating the transmittance of industrial dimming glass is achieved through the AC square wave dimming circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0037] Figure 1 1 is an overall structural diagram of an AC square wave dimming circuit according to an embodiment of the present invention;

[0038] Figure 2 1 is a structural diagram of an SPI to DAC circuit according to an embodiment of the present invention;

[0039] Figure 3 is a structural diagram of a DAC chip reference voltage circuit according to an embodiment of the present invention;

[0040] Figure 4 2 is a structural diagram of an operational in-phase and in-phase circuit according to an embodiment of the present invention;

[0041] Figure 5 is a structural diagram of a transistor controlled switch circuit according to an embodiment of the present invention;

[0042] Figure 6 is a structural diagram of a switch chip circuit according to an embodiment of the present invention;

[0043] Figure 7 is a structural diagram of an operational amplifier according to an embodiment of the present invention;

[0044] Figure 8 is a structural diagram of a first voltage conversion circuit in a power supply circuit according to an embodiment of the present invention;

[0045] Figure 9 is a structural diagram of a second voltage conversion circuit in a power supply circuit according to an embodiment of the present invention;

[0046] Figure 10 FIG. 4 is a structural diagram of a third voltage conversion circuit in a power supply circuit according to an embodiment of the present invention. DETAILED DESCRIPTION

[0047] The embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0048] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this application can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0049] like Figure 1As shown, the AC square wave dimming circuit includes: a central processing unit, an SPI to DAC circuit, a transistor control switch circuit, an operational inverse phase circuit, a switch chip circuit, a power supply circuit, and a power operational amplifier.

[0050] The central processing unit is connected to the SPI to DAC circuit through the SPI port of the central processing unit, the transistor control switch circuit is connected to the central processing unit through the PWM interface of the central processing unit, the operational inverse phase circuit is connected to the SPI to DAC circuit and the switch chip circuit respectively, the switch chip circuit is connected to the power operational amplifier, and the transistor control switch circuit, the switch chip circuit and the power operational amplifier are all connected to the power supply circuit.

[0051] The central processing unit is used to change the duty cycle of the power supply, the SPI to DAC circuit is used to provide 4-way dimming output for the central processing unit, the transistor control switch circuit is used to increase the voltage range to 0-5V, the switch chip circuit is used to output a square wave signal to the power operational amplifier, the operational amplifier is used to adjust the output voltage and output current and output them through the external interface, and the power supply circuit is used to provide power for the transistor control switch circuit, the switch chip circuit and the power operational amplifier.

[0052] In one embodiment of the present invention, the dimming control board can use the RK339K platform. The RK3399K is a 64-bit six-core processor with an ARM Cortex-A72 dual-core 1.8GHz and a Cortex-A53 quad-core 1.4GHz. It is equipped with 4GB of memory as standard and 8GB of EMMC storage space as standard. 3-way RS485 uses an isolation solution chip; 2-way RS232 also uses an isolation solution; 2-way USB power supply uses an isolated power supply; 1 100M network port; 5-way GPIO detection; 2-way 12V output; an analog circuit solution is used to output 4-way voltage of ±24V, power of 10W, frequency of 60HZ, and duty cycle of 50% dimming interface.

[0053] The hardware dimming component consists of digital-to-analog conversion (SPI interface to DAC), operational amplifiers for both inverting and non-inverting amplification, switch rectification, a power operational amplifier for inverting amplification, and a power supply. The hardware operates as follows: the PC communicates with the dimming board via a USB-to-RS485 interface. Commands are sent to the RK3399K via the PC serial port, which receives them and converts the analog voltage via the SPI interface. The analog voltage then undergoes inverting and non-inverting amplification in the first-stage operational amplifier, generating an AC square wave for the switch chip. This is then amplified by the second-stage power operational amplifier for inverting amplification, resulting in a ±24V output with 10W power, a 60Hz frequency, and a 50% duty cycle.

[0054] Because the RK3399K of the dimming board lacks analog DAC pin output, it is necessary to connect the chip DAC7614U_1K through the SPI interface of RK3399K to realize the SPI interface to DAC. The DAC pin outputs an analog voltage of 0-2.5V; the analog voltage 0-2.5V is amplified in the same phase and inverting phase by the operational amplifier; the positive and negative voltages are given to a switch chip respectively, and the PWM pin of RK3399K outputs a square wave with a frequency of 60HZ, a duty cycle of 50%, and a voltage of 0-1.8V. After the transistor, the 0-1.8V is converted into a range of 0-5V to control the switch chip to achieve a frequency of 60HZ, a duty cycle of 50%, and a voltage of ±10V; the frequency of 60HZ, the duty cycle of 50%, and the voltage of ±10V are output through the power operational amplifier with a frequency of 60HZ, a duty cycle of 50%, and a voltage of ±24V.

[0055] Because the CPU's dimming board requires four dimming outputs, an SPI-to-DAC circuit (such as the DAC7614U_1K chip) is used to implement these four DAC outputs. These four DACs offer two outputs: a -2.5V to 2.5V output and a 0V to 2.5V output. To achieve a -2.5V to 2.5V output, the SPI-to-DAC circuit's VDD pin must be connected to 5V, VSS to -5V, and VREFH to a 2.5V reference voltage. To achieve a 0-2.5V output, the SPI-to-DAC circuit's VDD pin must be connected to 5V, VSS to ground, and VREFH to a 2.5V reference voltage. To achieve a 0-2.5V output, the SPI-to-DAC circuit's VDD pin must be connected to 5V, VSS to ground, and VREFH to a 2.5V reference voltage. The CS, CLK, and SDI of the DAC7614U_1K are connected to the SPI1_CS, SPI1_CLK, and SPI1_DSI pins of the central processing unit, respectively, to implement communication between the central processing unit's SPI interface and the DAC7614U_1K, and a 22Ω resistor is connected in series for SPI impedance matching. The register reset pin RESETSEL, chip reset pin RESET, and chip latch status pin LOADDACS of the SPI-to-DAC circuit are connected to the CPU's GPIO port pins, respectively. After power-on, wait for the RK3399K to complete startup before pulling the RESETSEL, RESET, and LOADDACS pins high. This solution uses a 0-2.5V output, so a voltage reference chip REF3025AIDBZR is required to convert 3.3V to 2.5V and connect it to the VREFH pin with two capacitors for filtering. The VREFHL pin is connected to ground, VDD needs to be connected to 5V and two capacitors for filtering, and VSS is grounded. The central processing unit controls the DAC of the SPI to DAC circuit to output 0-2.5V.

[0056] like Figure 2As shown, the SPI to DAC circuit includes a digital-to-analog converter.

[0057] The digital-to-analog converter includes a VDD pin, a VDD pin, a VREFL pin, a VREFH pin, a VSS pin, a CS pin, a CLK pin, an SDI pin, a register reset pin RESETSEL, a chip reset pin RESET, and a chip latch status pin LOADDACS. The VDD pin is connected to a 5V reference voltage, the VSS pin is connected to a -5V reference voltage, the CS pin, the CLK pin, and the SDI pin are connected in series with a first resistor R577, a second resistor R578, and a third resistor R579, respectively, and then connected to the SPI1_CS pin, SPI1_CLK pin, and SPI1_DSI pin of the central processing unit. The VREFL pin is connected to a 2.5V reference voltage, the VREFH pin is connected to a -2.5V reference voltage, and the register reset pin RESETSEL, chip reset pin RESET, and chip latch status pin LOADDACS are each connected to a GPIO pin of the central processing unit.

[0058] The embodiment of the present invention uses an operational amplifier for in-phase and inverting amplification. The 0-2.5V output of the DAC chip reference voltage circuit requires 4 times in-phase amplification and 1 time in inverting amplification, and the output voltage supports -10V to 10V.

[0059] like Figure 3 and Figure 4 As shown, the operational in-phase and out-phase circuit includes: a DAC chip reference voltage circuit, a first operational amplifier and a second operational amplifier. The output voltage of the DAC chip reference voltage circuit is connected to the +IN pin of the first operational amplifier through a fourth resistor R504 connected in series. The -IN pin of the first operational amplifier is connected to the fifth resistor R500 and then to ground. It is connected to the OUT pin of the first operational amplifier after connecting to the sixth resistor R501 and the first capacitor C501. The OUT pin of the first operational amplifier is connected to the seventh resistor R503 and then to the output control switch SA1. The voltage of the output control switch SA1 is connected in series with the eighth resistor R516 and then to the -IN pin of the second operational amplifier and is connected to the OUT pin of the second operational amplifier after connecting to the ninth resistor R512 and the second capacitor C505. The +IN pin of the second operational amplifier is connected to the tenth resistor R514 and to ground. The OUT pin of the second operational amplifier is connected to the eleventh resistor R513 and the third capacitor C519. The V-0 pin, V-1 pin, and V-2 pin of the first operational amplifier and the second operational amplifier are all connected to a -24V voltage. The V+ pins of the first operational amplifier and the second operational amplifier are connected to a +24V voltage. The FLAG pins of the first operational amplifier and the second operational amplifier are grounded.

[0060] The embodiment of the present invention uses a switch chip to output a square wave signal with a voltage of ±10V, a frequency of 60HZ, and a duty cycle of 50%.

[0061] like Figure 5 As shown, the transistor control switch circuit includes a transistor. In order to increase the driving capability and avoid the critical point of the control voltage, the voltage range is increased to 0-5V through the transistor.

[0062] The base of the transistor is connected to the PWM port of the CPU via the sixteenth resistor R627. The collector of the transistor is connected to the IN1 port of the switch chip circuit. The emitter of the transistor is connected to ground via the seventeenth resistor R626 and the eighteenth resistor R649.

[0063] like Figure 6 As shown, the switch chip circuit includes: S1A pin, S1B pin, D1 pin, D2 pin, VDD pin, VSS pin, and PAD pin.

[0064] Connect the VDD pin to +15V, and the VSS and PAD pins to -15V. The S1A, S1B, and D1 pins form a single-way switch. The D1 and D2 pins output a ±10V square wave signal with a 60Hz frequency and a 50% duty cycle.

[0065] The embodiment of the present invention uses a power operational amplifier to convert ±10V to ±24V voltage output, and produces a square wave signal with a frequency of 60 Hz and a duty cycle of 50%. In one embodiment of the present invention, the power operational amplifier uses OPA544FKTTT.

[0066] like Figure 7 As shown, the power operational amplifier includes: output connector J5_A2, VIN- pin, VO pin, and VIN+ pin. The switch chip is connected to the VIN- pin via a twelfth resistor R634, and to the VO pin via a thirteenth resistor R635 and a fourth capacitor C667. The VIN+ pin is grounded via a fourteenth resistor R706, and the VO pin is connected to the 1-pin pin of the output connector J5_A2 via a fifteenth resistor R640. The VO pin is also grounded via a fifth capacitor C600.

[0067] The D pin of the switch chip outputs a ±10V square wave signal with a frequency of 60Hz and a duty cycle of 50%. However, the switch chip does not support high power and cannot meet the required 10W output of the four-way dimming output. The output voltage is ±24V. Therefore, a power operational amplifier chip is required with an output voltage range of ±35V and an output current of 2A. The D pin of the switch chip is connected to the VIN- pin of the power operational amplifier by resistor R634, and resistors R635 and C667 are connected to the VO pin of the operational amplifier. VIN+ is connected to resistor R706 to ground. The inverting gain is achieved through resistor -(R635 / 634) = -2.4. The VO pin of the operational amplifier is connected to resistor R640 and pin 1 of the output connector J5_A2 and stabilized by capacitor C600. The output voltage is -2.4X±10V = ±24V. Pin 2 of J5_A2 is connected to R708 to ground.

[0068] To improve integration and miniaturization, this power module is designed for use on a dimming board. The relevant circuits in the 24V AC square wave solution require 12V, 5V, ±15V, and ±24V power supplies. In one embodiment, the power supply circuit utilizes the TPS54A24RTW (5V input, 10A output), the ADP1613ARMZ-R7 (±15V input, 2A output), and the ADP5070AREZ (±24V input, 2A output). The input voltage of the power supply circuit is 12V. The 5V voltage is used to boost and negatively convert the voltage in the ADP1613ARMZ-R7 chip and power the PWM switching function; the 12V voltage is used to boost and negatively convert the voltage in the ADP5070ARE chip.

[0069] like Figures 8 to 10 As shown, the power supply circuit includes: a first voltage conversion circuit, a second voltage conversion circuit and a third voltage conversion circuit.

[0070] like Figure 8 As shown, the first voltage conversion circuit is used to convert 12V to 5V.

[0071] like Figure 9 As shown, the second voltage conversion circuit is used to convert 5V into ±15V.

[0072] like Figure 10 As shown, the third voltage conversion circuit is used to convert 12V into ±24V.

[0073] Beneficial effects of the embodiments of the present invention:

[0074] The AC square wave dimming control circuit of the present invention is primarily used to provide an AC square wave signal for adjusting the transmittance of dimming glass. It utilizes a DC12V power supply and features two RS232, three RS485, two controllable 5V outputs, one Ethernet communication interface, two USB ports, five IO ports, two controllable 12V outputs, and four ±24V dimming interfaces with 10W power, 60Hz frequency, and a 50% duty cycle. The dimming board can communicate with a capacitive touch panel via the RS485 interface to collect dimming control signals provided by the panel. It can also receive dimming control touch signals from the capacitive touch panel via USB, generating a corresponding AC square wave signal for adjusting the transmittance of the dimming glass. The board also includes an onboard CPU debugging interface and a programming interface for an external capacitive touch panel to facilitate board maintenance. The transmittance of industrial dimming glass can be adjusted using the present invention.

[0075] The above description is merely a specific embodiment of the present invention and should not be construed as limiting the scope of the invention. Therefore, substitutions of equivalent components, or equivalent changes and modifications made within the scope of patent protection, should still fall within the scope of this patent. Furthermore, the technical features of the present invention may be freely combined with one another, with other technical solutions, and with other technical solutions.

Claims

1. An AC square wave dimming circuit, characterized in that: include: Central processing unit, SPI to DAC circuit, transistor control switch circuit, operational inverse phase circuit, switch chip circuit, power supply circuit, power operational amplifier; The central processing unit is connected to the SPI to DAC circuit via the SPI port of the central processing unit, the transistor control switch circuit is connected to the central processing unit via the PWM interface of the central processing unit, the operational inverse phase circuit is connected to the SPI to DAC circuit and the switch chip circuit respectively, the switch chip circuit is connected to the power operational amplifier, and the transistor control switch circuit, the switch chip circuit and the power operational amplifier are all connected to the power supply circuit; The central processing unit is used to change the duty cycle of the power supply, the SPI to DAC circuit is used to provide four dimming outputs for the central processing unit, the transistor control switch circuit is used to increase the voltage range to 0-5V, the switch chip circuit is used to output a square wave signal to the power operational amplifier, the power operational amplifier is used to adjust the output voltage and output current and output them through an external interface, and the power supply circuit is used to provide power for the transistor control switch circuit, the switch chip circuit and the power operational amplifier; The power supply circuit comprises: a first voltage conversion circuit, a second voltage conversion circuit, and a third voltage conversion circuit; The first voltage conversion circuit is used to convert 12V to 5V; The second voltage conversion circuit is used to convert 5V to ±15V; The third voltage conversion circuit is used to convert 12V into ±24V; The transistor control switch circuit comprises: triode; The base of the transistor is connected to the PWM port of the central processing unit through a sixteenth resistor R627; The collector of the transistor is connected to the IN1 port of the switch chip circuit; The emitter of the transistor is grounded after passing through the seventeenth resistor R626 and the eighteenth resistor R649.

2. The AC square wave dimming circuit according to claim 1, characterized in that: The SPI to DAC circuit includes a digital-to-analog converter; The digital-to-analog converter includes a VDD pin, a VREFL pin, a VREFH pin, a VSS pin, a CS pin, a CLK pin, an SDI pin, a register reset pin RESETSEL, a chip reset pin RESET, and a chip latch status pin LOADDACS; The VDD pin is connected to a 5V reference voltage, the VSS pin is grounded, the CS pin, the CLK pin, and the SDI pin are respectively connected in series with a first resistor R577, a second resistor R578, and a third resistor R579, and then connected to the SPI1_CS pin, SPI1_CLK pin, and SPI1_DSI pin of the central processing unit. The VREFL pin is connected to a 2.5V reference voltage, the VREFH pin is connected to a -2.5V reference voltage, the register reset pin RESETSEL, the chip reset pin RESET, and the chip latch status pin LOADDACS are respectively connected to the GPIO pins of the central processing unit.

3. The AC square wave dimming circuit according to claim 1, characterized in that: The operational in-phase and out-phase circuit comprises: DAC chip reference voltage circuit, first operational amplifier and second operational amplifier; The output voltage of the DAC chip reference voltage circuit is connected to the +IN pin of the first operational amplifier through a fourth resistor R504 in series, the -IN pin of the first operational amplifier is connected to the fifth resistor R500 and then to ground, and is connected to the OUT pin of the first operational amplifier after connecting the sixth resistor R501 and the first capacitor C501, the OUT pin of the first operational amplifier is connected to the seventh resistor R503 and then to the output control switch SA1, the voltage of the output control switch SA1 is connected in series with the eighth resistor R516 and then to the -IN pin of the second operational amplifier and connected to the ninth resistor R512 and the second capacitor C505 are connected to the OUT pin of the second operational amplifier, the +IN pin of the second operational amplifier is connected to the tenth resistor R514 and grounded, the OUT pin of the second operational amplifier is connected to the eleventh resistor R513 and the third capacitor C519, the V-0 pin, V-1 pin, and V-2 pin of the first operational amplifier and the second operational amplifier are all connected to a -24V voltage, the V+ pin of the first operational amplifier and the second operational amplifier is connected to a +24V voltage, and the FLAG pins of the first operational amplifier and the second operational amplifier are grounded.

4. The AC square wave dimming circuit according to claim 1, characterized in that: The switch chip circuit includes: S1A pin, S1B pin, D1 pin, D2 pin, VDD pin, VSS pin, PAD pin; The VDD pin is connected to a +15V voltage, and the VSS pin and the PAD pin are connected to a -15V voltage; The S1A pin, the S1B pin, and the D1 pin constitute a 1-way switch; The D1 and D2 pins output a square wave signal with a voltage of ±10V, a frequency of 60HZ, and a duty cycle of 50%.

5. The AC square wave dimming circuit according to claim 1, characterized in that: Power operational amplifiers include: Output connector J5_A2, VIN- pin, VO pin and VIN+ pin; The switch chip is connected to the VIN- pin through the twelfth resistor R634, and is connected to the VO pin through the thirteenth resistor R635 and the fourth capacitor C667. The VIN+ pin is grounded through the fourteenth resistor R706. The VO pin is connected to the 1PIN pin of the output connector J5_A2 through the fifteenth resistor R640, and the VO pin is grounded through the fifth capacitor C600.

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