Dear Harry,
Thanks for your reply.
What confuses me is that, REF pin can ALSO be used as an output in the "external reference internal buffer mode". It is not mentioned explicitly that REF pin can be used as an output in the "internal reference mode".
That is to say, I could not conclude that REF pin can be used as a source simply from the spec table, since it can also be used as an output in another mode.
Thank you very much.
Regards,
Richie