I am working on a known good customer design. They have built many of these and they work. We have tried to replicate their design and are having problems. The Input voltage is 16-24 Volts and the output is 1.8V. One of the differences that we have noticed is that the duty cycle and waveform shape of HO and LO is different from the working unit they provided us. Theirs has a duty cycle close to 40% and it varies slightly cycle to cycle. Ours is a very narrow pulse both on the LO and the HO. The oscillator frequency is 172Khz.
We have checked values of all the parts, have replaced the regulator, have built up several boards and they all behave the same way. The output voltage does match the desired voltage but HO and LO signal look wrong.
If anyone could suggest why this might be such a narrow pulse and where we could look to better understand the way the chip is behaving, it would be very much appreciated.
