I need Positive and negative from a 5V input

Hi

I have built some kits with LM5160 with Fly-Buck-Boost topology but I'm not satisfied with the performance.

the drop-out voltage is around 2~3V for only 400mA. but the IC is very robust against some over-current at the output.

Vin=4.5~5.5V

Vo+ (under the load) = 5.5V

Io+ = 600mA

Vo- (under the load) =-5.5V

Io-= 200mA

now I want to design two separate kit that each one generates a positive or a negative voltage.

Do you know a proved and compact circuit? I want to put it beside my FPGA and sensor kits.

Thanks