F2002 ADC Question

Hi Marcelo,

as per datasheet spec, you can run at VCC=2.8V and use the internal reference at V_REF=2.5V if you limit the current drawn from the reference to 500uA. Also, the total unadjusted error given for the ADC10 does not include the error that could be caused by the voltage reference (as you can see if you calculate the worst-case error contribution of the reference, it exceeds the total unadjusted error spec).

Regards,
Andreas

Hi Andres:

Sorry to reply again but the datasheet shows VCC = 3V for V_REF = 2.5V (even for 500uA limit).  I am looking at this page 40 of F2002 datasheet (slas491d.pdf). Thanks.

The number you are referring to is a test condition used to specify the reference behavior under maximum allowed load. If you limit your load to 500uA (the spec above) you can get away having VCC at 2.8V as per the other spec.

Regards,
Andreas

Sorry for my stupid question , but what do you mean when you say 500uA load ??

You mean that current on ADC input cannot be more than 500uA ?

Thanks

Andreas:

I do not plan on using VREF to supply anything else.  I think this is what you were concerned about regarding the 500uA limit.  Is this correct?  Thanks.