LMZ31520: about out put maximum capacitance

Hi,

Could you tell me about LMZ31520/LMZ31530 out put maximum capacitance?
Customers want to increase output capacitors to reduce ripple.
Please tell me the maximum capacitance you recommend.

I have one more question.
Customer want to increase the operating frequency for the purpose of reducing the ripple.
The data sheet has the following description.

・Frequency Select (kHz)   ・Vout RANGE(V)
・650kHz                             ・1.0V(min) 3.6V(max)

Is the settable frequency up to 650kHz in Vout=0.9V condition?
If so, please tell me the reason.

Customer target spec is:
Vin=8V
Vout=0.9V
Iout=16A
target out put ripple=±20mV

Could you give me your advice?

Best Regards,
Yusuke/Japan Disty