What is the output impedance of the Vref pin on the AD9208?
Refer to the "Diode Based Temperature measurements" section in this document:
If you are measuring the voltage from the temp diode you don't want to load that diode or the current can change and your measurement won't be accurate. You will need to sample that voltage with a high impedance so the current draw from the diode is minimal.
It is a high impedance input. We recommend using the ADR130 as an external reference to drive the VREF pin. That part can drive 4mA to -2mA.
I'm more interested in thisfrom the viewpoint of using the Vref pin to measure temperatures and whether or not I need to buffer it. What current can this pin supply?
No, if you are measuring the temperature of the device you won't need to buffer it. Refer to the Temprature diode section of the datasheet.
There is no mention of drive capability in that section or in the Specifications section, hence the question. Do you have a figure for the load that the temperature diode output can drive? This issue is holding up my design..
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