Effects of negative peak input current in charge pump

[asorab123]

Our study is about switched capacitor dc-dc converters and we are having problems with the peak input current. Our first design has 2.4A peak input current with input voltage of 1.5V (from battery) and the battery is only 200mAh (the output is 2.2V with 97.1mA output current which meet our specifications). We modified the circuit and then we get a 700mA peak input current but the negative peak is -2.4A (output is still the same). What does this mean? Is it good or bad for our converter? Thanks for any response...

 

[FvM]

In a usual design, the DC/DC converter provided an input filter capacitor which isolates at least part of the peak current from the battery. The peak current is unlikely to harm the battery, but will cause unwanted losses.

 

[BradtheRad]

700mA peak input current but the negative peak is
-2.4A

This implies that current is travelling mostly out of the power supply, but at times backward into it. Is this really what you observe?

 

[BradtheRad]

Besides installing the input capacitor, by adding a choke inductor in the supply line you effectively draw constant current (more or less) from the supply.

 

[FvM]

I think that a negative current peak isn't expectable for a correctly designed switched capacitor converter.