Hi
I have a board using the LM27761 and I followed the recommendation for a flying capacitor of between 470nF and 1uF and placed a 1uF but this does not charge the capacitor up properly on my board. I found that I have to use a flying capacitor of 100nF or less to get it to work.
My potential divider circuit is 261K and 100K which is set to give me approx. -4.4V for an input of 5V. I loaded the output with 10uF and 1K to give it some load.
Maybe I am doing something wrong but there isnt much to do wrong with so few components for this device? With a 1uF flying capacitor the device just does not drive the flying capacitor well at all. But with 100nF it comes to life perfectly.
Any thoughts on why this is?
Trev