TPS62827: power ripple problem

Hi Team,

customer target ripple should less than 3% of output voltage(for output=0.8V ripple should smaller than 24mV)

But however, ripple is about 8%

We have tried

1. bigger output cap(original is 1 x 22uF,we add to 2 x 22uf)
2. install feedforward cap(280pf)
3. change different inductance(1uH).

but ripple seems no big difference compare to original setting.

Do you have any suggestion for this situation?

Thanks.