Crm Icbg (wuxi) Co. Ltd.

Quanqing Wu

Guocheng Li

Jun Liu

A PWM signal conversion circuit and method, and an LED dimming system. The circuit includes: a PWM signal detection module, which outputs a first voltage corresponding to a low-level time of the PWM signal and a second voltage corresponding to a high-level time of the PWM signal; an addition module, which sums the first and second voltages to obtain a third voltage; a switch signal generation module, which generates a switch signal based on the third voltage; a duty cycle ratio generation module, which obtains a duty cycle ratio of the PWM signal based on a counting to the high level of the PWM signal by the switch signal; and an output voltage generation module, which obtains an output voltage related to a duty cycle of the PWM signal based on the duty cycle ratio.

PWM signal conversion circuit and method, and LED dimming system

A LED dimming circuit, including a low-level-voltage generation module, a high-level-voltage generation module, a base-voltage generation module, and a dimming-signal generation module. By counting the high and low levels of a low-frequency PWM signal, high and low-level voltages with respect to time are obtained; a constant current source and a capacitor are used to convert high-frequency switching signals to a DC base voltage that is only related to the duty cycle of the low-frequency PWM signal. When the base voltage is greater than a predetermined voltage, the base voltage is output as the dimming signal; when the base voltage is less than the predetermined voltage, a new PWM signal is output as the dimming signal, whose magnitude is the same of that of the predetermined voltage, wherein the average values of the new PWM signal and the base voltage are the same.

LED dimming circuit

An LED driving system and a closed-loop control method for LED driving are provided; the LED driving system includes an LED load, a constant-current control module, an electrolytic capacitor, a discharging-voltage measuring module, a bus-voltage measuring module and a charging-current control module, wherein the charging-current control module is connected to an output of the discharging-voltage measuring module, the bus-voltage measuring module and a lower plate of the electrolytic capacitor; the charging current of the electrolytic capacitor is adjusted based on the control signal of the discharging-voltage measuring module and the measured voltage of the bus-voltage measuring module, wherein the charging current of the electrolytic capacitor is reduced by an subtraction operation performed by the addition and subtraction counter, and the charging current of the electrolytic capacitor is increased by an addition operation performed by the addition and subtraction counter.

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Jiangsu, China

Quanqing Wu