Lighting control circuit, lighting control method, and lighting circuit

Patent metadata

Field	Value
Publication number	US-12598680-B2
Application number	US-202418590802-A
Country	US
Kind code	B2
Filing date	Feb 28, 2024
Priority date	Mar 13, 2023
Publication date	Apr 7, 2026
Grant date	Apr 7, 2026

Abstract

The present application discloses a lighting control circuit, a lighting control method, and a lighting circuit. The lighting control circuit includes at least a protocol conversion circuit, and a driving signal generation circuit. The dimming selection circuit stores an input data signal as multi-channel digital signals. The driving signal generation circuit controls an off time of a main power transistor according to a first dimming signal derived from the multi-channel digital signals in a first dimming mode, and controls an off time of the main power transistor according to a reference signal derived from the multi-channel digital signals and an output feedback signal in a second dimming mode. The lighting control circuit according to the present disclosure stores the input data signal as multi-channel digital signals, and the circuit can be configured with different dimming modes according to the protocol alone to improve the circuit flexibility.

First claim

What is claimed is:

1 . A lighting control circuit, comprising:
a main power transistor; a protocol conversion circuit that stores received input data signal as multi-channel digital signals; a dimming selection circuit that is coupled to the protocol conversion circuit, and selects a second-channel digital signal and a third-channel digital signal to be output as a first dimming signal or a third-channel digital signal to be output as a second dimming signal according to a value of a first-channel digital signal; a feedback circuit that is coupled to the dimming selection circuit and generates a reference signal according to the second dimming signal and an output feedback signal; and a driving signal generation circuit that is coupled to the dimming selection circuit, the feedback circuit, and a control terminal of the main power transistor, and generates a driving signal according to the first dimming signal to control an off time of the main power transistor to achieve a first dimming mode, and generates a driving signal according to the reference signal and the output feedback signal to control an off time of the main power transistor to achieve a second dimming mode, wherein the first dimming mode is a chopper dimming mode, the second dimming mode is an analog dimming mode, the first dimming signal is a PWM dimming signal, and the second dimming signal is an analog dimming signal.

2 . The lighting control circuit according to claim 1 , wherein the driving signal generation circuit adjusts a duty ratio of the driving signal according to the first dimming signal to adjust a value of a current flowing through the main power transistor; and the feedback circuit adjusts an off time of the main power transistor by adjusting a value of the reference signal according to the second dimming signal to adjust a peak value of a current flowing through the main power transistor.

3 . The lighting control circuit according to claim 1 , wherein the dimming selection circuit comprises:
a dimming mode selection unit that outputs a first selection signal or a second selection signal according to a value of the received first-channel digital signal for configuring a dimming mode; a first DAC unit that converts the third-channel digital signal into the analog dimming signal and a brightness regulation parameter according to the second selection signal; and a PWM generator that receives the second-channel digital signal and the brightness regulation parameter to output the PWM dimming signal according to the first selection signal.

4 . The lighting control circuit according to claim 1 , wherein the protocol conversion circuit comprises:
a decoder that decodes the input data signal for transmission in a plurality of bits; a register bank that has a plurality of registers for sequentially storing a plurality of bits and outputting them as the multi-channel digital signals; a second DAC unit that is coupled to an output of the register bank, and converts the multi-channel digital signals into a plurality of regulation parameters.

5 . The lighting control circuit according to claim 1 , wherein the feedback circuit comprises:
a first voltage source and a second voltage source that are coupled in series between a power supply terminal and a ground terminal; a compensation capacitor that is coupled between an intermediate node of the first voltage source and the second voltage source and the ground terminal; and a controlling logic unit that is coupled to the intermediate node, wherein the first voltage source and the second voltage source receive the analog dimming signal and the output feedback signal, respectively, to adjust a voltage across the compensation capacitor, the voltage being output from the controlling logic unit as the reference signal and a first timing signal.

6 . The lighting control circuit according to claim 5 , wherein the driving signal generation circuit comprises:
a comparator that is coupled to the controlling logic unit, compares the reference signal and the output feedback signal, and outputs a comparison signal; an on-time delay unit that is coupled to the control logic unit to obtain a delayed second timing signal according to the first timing signal; a zero-crossing detection unit that is coupled to an AND gate together with the on-time delay unit, the zero-crossing detection unit receiving a voltage signal representing an inductor current and outputting a zero-crossing detection signal when the voltage signal indicates that the inductor current crosses zero, the AND gate receiving the zero-crossing detection signal and outputting a third timing signal after receiving the second timing signal; a driving logic unit that generates a first control signal according to the comparison signal, the PWM dimming signal, and a maximum on-time signal, and generates a second control signal according to the third timing signal and a maximum off-time signal, and generates the driving signal according to the first control signal and the second control signal to control on and off states of the main power transistor.

7 . The lighting control circuit according to claim 6 , wherein the driving unit controls an off time of the main power transistor according to the driving signal derived from the first control signal, and controls an on time of the main power transistor according to the driving signal derived from the second control signal.

8 . The lighting control circuit according to claim 4 , further comprising:
a protection circuit that is coupled to the protocol conversion circuit and the driving signal generation circuit, and converts the regulation parameters output from the protocol conversion circuit into physical parameter thresholds, and protects the lighting control circuit when the sampled physical parameters reach the physical parameter thresholds.

9 . The lighting control circuit according to claim 8 , wherein the protocol conversion circuit converts a fourth-channel digital signal into an over-voltage protection regulation parameter and a fifth-channel digital signal into an over-temperature protection regulation parameter, wherein the protection circuit comprises:
an over-voltage protection unit that obtains at least one over-voltage protection threshold according to the over-voltage protection regulation parameter, and outputs an over-voltage protection signal to the driving signal generation circuit when an output voltage exceeds the over-voltage protection threshold; and an over-temperature protection unit that obtains at least one over-temperature protection threshold according to the over-temperature protection regulation parameter, and outputs an over-temperature protection signal to the driving signal generation circuit when the circuit temperature exceeds the over-temperature protection threshold.

10 . The lighting control circuit according to claim 1 , wherein the protocol conversion circuit converts the input data signal into the multi-channel digital signals with a single-wire communication protocol or a serial communication protocol, the single-wire communication protocol including unipolar Return-to-Zero coding, non-unipolar Return-to-Zero coding, bipolar Return-to-Zero coding and non-bipolar Return-to-Zero coding.

11 . The lighting control circuit according to claim 9 , wherein the first-channel digital signal consists of a 1 bit, the second-channel digital signal consists of a 2 bits, the third-channel digital signal consists of 8 bits, the fourth-channel digital signal consists of 2 bits, and the fifth-channel digital signal consists of 2 bits.

12 . A lighting circuit, comprising:
multi-channel LED strings; and t

Assignees

• Joulwatt Tech Co Ltd

Inventors

• Wu Minghao
• Liu Guoqiang

Classifications

• H05B45/325 Primary

  Pulse-width modulation [PWM] · CPC title

• H05B45/3725

  Switched mode power supply [SMPS] · CPC title

• H05B45/10

  Controlling the intensity of the light · CPC title

• H05B45/14 Primary

  using electrical feedback from LEDs or from LED modules · CPC title

• H05B45/50

  responsive to malfunctions or undesirable behaviour of LEDs; responsive to LED life; Protective circuits · CPC title