LTC2000 FSADJ speed

Hi,

as mentioned in the Datasheet of the LTC2000 the FSADJ pin current can be used to adjust the full-scale output of the DAC within a certain limit (10mA-60mA). What is the speed limit of this input? 

I had the idea to use this pin to scale the output amplitude to increase the resolution in a regulator application but there cannot be too much delay i.e. the response-time must be below 10µs. Is there any information available on this subject?

Best regards,

Damian