charge pump LM2662 impact the input

Hi

This post belongs on the non-isolated dc/dc forum, I will move it for you.

Regards

Peter

Hello,

At what load current are the waveforms being taken at?  The output ripple does look high and the input appears to me moving a bit.  What is the resistance of L101?  If this is high and the load current is high, you will see larger ripple.

If you power the LM2662 by itself using an external supply on the right hand side of the L101, does the ripple decrease?

Greg

hello，

1、the load current is about 80mA;

2、L101 is a bead, the resistance is 471Ω @ 100MHz; will the ripple smaller if the bead be removed?

3、power the LM2662 by itself using an external supply on the right hand side of the L101, the ripple at the input is lager , about 200mV, like below:

What does the PCB layout look like for the input and output cap grounds with respect to the LM2662 ground? Also, if you increase the input capacitor (C1102) to a 47uF value, does the output quiet down?