Abstract: A noise reduction circuit for a matrix LED driver includes a pseudo random number generator, an up counter, a clock module, and a plurality of matrix switch controllers. The matrix switch controllers and the up counter randomly change a power-on sequence applied across matrix switches in the matrix LED driver according to working random numbers generated by the pseudo random number generator. The circuit prevents jitter-induced noise from periodically reoccurring at the power source of the matrix LED driver, thereby reducing noise energy.

Abstract: A power transistor overcurrent protection circuit includes an overcurrent detection circuit, a timing control circuit, and an enable control circuit. The overcurrent detection circuit is configured to detect whether there is an overcurrent flowing in the controlled power transistor. The timing control circuit and the enable control circuit jointly control the controlled power transistor. The power transistor overcurrent protection circuit can turn off the controlled power transistor so as to protect the controlled power transistor when there is an overcurrent flowing in the controlled power transistor for controlling a load to work or not to work.

Abstract: A spread spectrum clock generating system is provided. The digital frequency detecting unit is configured for receiving a reference signal and a feedback signal and for comparing the reference signal and the feedback signal to generate a frequency difference signal. The digital loop filtering unit is signally connected to the digital frequency detecting unit and outputs a clock controlling signal based on the frequency difference signal. The digital spread spectrum controlling unit is configured for receiving the reference signal to output a spread spectrum signal. The digital-analog converting unit is configured for converting the clock controlling signal to a first controlling signal and for converting the spread spectrum signal to a second controlling signal. The analog controlled oscillating unit is configured for receiving the first controlling signal and the second controlling signal to output a spread spectrum clock signal.

Abstract: A low power consumption LED constant current drive circuit includes a power source input circuit, a constant current source circuit, an output voltage detection circuit, and a reference current control circuit, having the advantage of lower power consumption.

Abstract: A PWM signal generation and error calibration circuit includes an amplifier OP1, an amplifier OP2, a comparator CMP1, a comparator CMP2, PMOS field-effect transistors M1-M16, a resistor R14, a resistor R_FRE, variable resistors R15-R16, a resistor R17, a capacitor C1, a matched resistance module circuit, a current drain IDC, and a 14-bit counter. The PWM signal generation and error calibration circuit saves chip costs and supports a wide PWM signal frequency range, while being able to calibrate all duty cycle errors of PWM signals in the range between 0% and 100% with improved accuracy.

Abstract: A power tube driver of a class-D audio amplifier includes high-side and low-side fixed charge/discharge gate driving circuits, high-side and low-side power tubes, a dead time generation circuit based on gate voltage detection, high-side and low-side gate charge/discharge accelerating circuits, and high-side and low-side gate voltage detection circuits. The class-D audio amplifier with the features of low radiation interference, and high efficiency, linearity and robustness can be balanced easily.

Abstract: An LED dimming load sudden change suppression circuit is applied to an LED dimming circuit. The LED dimming load sudden change suppression circuit includes a MOS transistor Q1, a sampling resistor R1, an error amplifier U1, and a DC-DC module U2, which can ensure that the total current of the LED dimming circuit is constant and avoid damage to LEDs.

Abstract: A PWM control circuit for a driving chip and an LED driving chip for an automotive reading lamp are compatible to existing car interior lighting solutions, that is, PWM signals output by MCUs are used to turn on and off LEDs. Also provided is a PWM signal automatically generated within a driving chip and used to control the lighting status of an LED. By using PWM signals generated internally in chips to control LEDs, MCUs can be unburdened from complicated operation, and thereby can operate with improved efficiency.

Abstract: An LED driver chip for a car reading light and a state control method thereof are provided. The LED driver chip includes a state machine control circuit module, a state machine output logic module, a current on/off control logic circuit module, and a current source module. An OUT pin of the LED driver chip is connected with an LED. The LED driver chip determines the next state of LED current according to a driver chip PWM input signal, an EN pin low lever pulse input signal, and a present LED state, enabling the LED to switch among nine different states.

Abstract: A current clamp circuit based on BCD technology includes a current-outputting circuit, an output-current-sensing circuit, and a current clamp circuit. The current-outputting circuit outputs a current to the output-current-sensing circuit. The output-current-sensing circuit senses the output current. When the current actually output by the current-outputting circuit is greater than a clamp current, the current clamp circuit outputs a current clamp feedback control signal to the current-outputting circuit, so as to clamp the output current clamp at a set value.

Abstract: An LED scanning array driver chip and a regulation method capable of self-regulating brightness linear change are provided. The LED scanning array driver chip is provided with LED current non-linear automatic control circuits to automatically regulate the average current of LEDs for the brightness of the LEDs to become bright or dark linearly, enabling each LED of the LED array to control the current non-linear change individually. This greatly reduces the time resource for a MCU to write registers inside the driver chip.

Abstract: The present application provides a control device for controlling a switching converting module to generate an output signal of constant output current from a rectified AC power supply signal. The switching converting module comprises a primary winding for receiving the rectified AC power supply signal and a power switch coupled in series with the primary winding.

Abstract: The present application provides a control device for controlling a switching converting module to generate an output signal of constant output current from a rectified AC power supply signal. The switching converting module comprises a primary winding for receiving the rectified AC power supply signal and a power switch coupled in series with the primary winding.