A grounded voltage protection circuit for a linear drive circuit includes an AC-DC power supply module, a first voltage protection module, an LED module, a drive IC and a linear current adjustment module. Through the cooperation of the first voltage protection module, the drive IC and the linear current adjustment module, when a DC voltage signal output by the AC-DC power supply module exceeds a first preset voltage value, the first voltage protection module outputs the first preset voltage signal to prevent the drive IC and the LED module from being damaged due to the overvoltage output by the AC-DC module, and avoid the transient impulse voltage in the entire voltage protection circuit, thereby enabling the voltage protection circuit to pass the CEC certification.

A charge voltage calibration system comprises a power supply, a light string, a driver, and a calibration circuit. The driver comprises a capacitor, a switch, and a sense resistor. The switch, sense resistor, and light string are coupled in series to form a discharge path coupled in parallel with the capacitor. The calibration circuit comprises a controller, a DAC, a comparator, a memory device. The controller is configured to control the DAC to provide a reference voltage to the comparator, cause the power converter to supply a first charge voltage to the driver, cause the switch to transition from an off state to an on state to discharge stored energy in the capacitor through the discharge path, and store a value of the first charge voltage in the memory device in response to detection of voltage generated across the sense resistor being greater than or equal to the reference voltage.

A light-emitting element driving semiconductor integrated circuit that constitutes at least a portion of a light-emitting element driving device configured to drive a plurality of light-emitting elements connected in series includes: a controller configured to have a first mode in which switching control is performed on a transistor connected in series to the plurality of light-emitting elements and a second mode in which linear control is performed on the transistor; and a first detector configured to detect that a current flowing through a sense resistor connected in series to the plurality of light-emitting elements and the transistor reaches a threshold value, wherein the controller switches from the switching control to the linear control based on an output of the first detector.

A light-emitting element driving semiconductor integrated circuit that constitutes at least a portion of a light-emitting element driving device configured to drive a plurality of light-emitting elements connected in series includes: a controller configured to have a first mode in which switching control is performed on a transistor connected in series to the plurality of light-emitting elements and a second mode in which linear control is performed on the transistor; and a first detector configured to detect that a current flowing through a sense resistor connected in series to the plurality of light-emitting elements and the transistor reaches a threshold value, wherein the controller switches from the switching control to the linear control based on an output of the first detector.

A light-emitting diode (LED) backlight driving circuit is provided. The LED backlight driving circuit includes M LED light-emitting unit groups connected in series and each of the LED light-emitting unit groups includes N LED light-emitting units connected in parallel, where both N and M are an integer greater than 1, wherein each of the LED light-emitting units is connected in series with at least a variable resistor with variable resistance for balancing a voltage difference. The present application further provides a backlight module and a liquid crystal display device manufactured using the LED backlight driving circuit.

A light-emitting diode (LED) backlight driving circuit is provided. The LED backlight driving circuit includes M LED light-emitting unit groups connected in series and each of the LED light-emitting unit groups includes N LED light-emitting units connected in parallel, where both N and M are an integer greater than 1, wherein each of the LED light-emitting units is connected in series with at least a variable resistor with variable resistance for balancing a voltage difference. The present application further provides a backlight module and a liquid crystal display device manufactured using the LED backlight driving circuit.

There is provided a rear sign lamp capable of enhancing safety. An LED string (502) includes four LEDs (504_1 to 504_4) connected in series. An LED driver circuit (610) receives a battery voltage (V.sub.IN) and supplies a drive current (I.sub.LED) stabilized at a target current (I.sub.REF) to the LED string (502). A bypass circuit (620) is provided in parallel with a bypassed portion (503) including two adjacent LEDs (504_3 and 504_4) of the LED string (502), and sinks a bypass current (I.sub.BYPASS) according to a battery voltage (V.sub.IN).

There is provided a rear sign lamp capable of enhancing safety. An LED string (502) includes four LEDs (504_1 to 504_4) connected in series. An LED driver circuit (610) receives a battery voltage (V.sub.IN) and supplies a drive current (I.sub.LED) stabilized at a target current (I.sub.REF) to the LED string (502). A bypass circuit (620) is provided in parallel with a bypassed portion (503) including two adjacent LEDs (504_3 and 504_4) of the LED string (502), and sinks a bypass current (I.sub.BYPASS) according to a battery voltage (V.sub.IN).

A system and method to determine a health status of a LED light string. The system (100) includes a circuit that includes a LED light string (110) and a pulsed current driver (115) of the LED light string. The circuit is connected to a power source (105). The system includes a current sensor (120) measuring a current through the circuit. The system includes a detecting device (130) determining a state of the circuit. The detecting device determines an expected current expected to be passing through the circuit where the expected current is associated with the state. The detecting device receives a current measurement from the current sensor during a time when the circuit is in the state. The detecting device determines a comparison between the current measurement and the expected current. The detecting device generates an output indicative of a health status of the circuit based on the comparison.

A system and method to determine a health status of a LED light string. The system (100) includes a circuit that includes a LED light string (110) and a pulsed current driver (115) of the LED light string. The circuit is connected to a power source (105). The system includes a current sensor (120) measuring a current through the circuit. The system includes a detecting device (130) determining a state of the circuit. The detecting device determines an expected current expected to be passing through the circuit where the expected current is associated with the state. The detecting device receives a current measurement from the current sensor during a time when the circuit is in the state. The detecting device determines a comparison between the current measurement and the expected current. The detecting device generates an output indicative of a health status of the circuit based on the comparison.