PWM signal conversion circuit and method, and LED dimming system

A PWM signal conversion circuit, comprising at least:

• a PWM signal detection module configured to receive a PWM signal, detect a low-level time and a high-level time of the PWM signal, and output a first voltage corresponding to the low-level time and a second voltage corresponding to the high-level time;
• an addition module connected to an output end of the PWM signal detection module, configured to sum the first voltage and the second voltage to obtain a third voltage;
• a switch signal generation module connected to an output end of the addition module, configured to generate a switch signal based on the third voltage, wherein a frequency of the switch signal is higher than a frequency of the PWM signal;
• a duty cycle ratio generation module connected to an output end of the switch signal generation module, configured to start counting the switch signal at a rising edge of the PWM signal, end the counting at a falling edge of the PWM signal, and obtain a duty cycle ratio of the PWM signal;
• and
• an output voltage generation module connected to an output end of the duty cycle ratio generation module, configured to obtain an output voltage related to a duty cycle of the PWM signal based on the duty cycle ratio of the PWM signal.