This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

LM555 PWM circuit, capacitor charges twice during one clock cycle?

Other Parts Discussed in Thread: LM555, NE555

Hello,

I am using a LM555 to build a PWM circuit. I configured the chip as per the PWM application circuit in NE555 datasheet (fig 18, circuit for pulse width modulation).

 input frequency = 72KHz

C5 = 0.01u F

RA = 4.7K ohm

The circuit works OK between 50-90% duty cycle, but at lower duty cycle the capacitor charges up more than once per clock cycle.I tried different conbinations of clk freu and RA, but it doesn't seem to be able to solve problem

What is the reason for this? Is there a combination of the above parameters that can provide a stable PWM between 10-90%


Thank you for the help