Part Number: ADS1298
Hi,
Currently we're designing a device that has 3x the ADS1298 to measure 24 electrodes.The absolute accuracy of the reference isn't that critical so potentially the internal reference with 0.2% typ. accuracy can be used. However, the typ. 0.2% reference tolerance between the 3 devices is too high. Ideally all references would be the same for a maximum gain error of 0.5%FS.
Since board space is at a premium my preferred solution would be to connect the 3 VCAP1 pins together (via internal 10k5 resistor for 4V) resulting in the average of the 3 references as common reference. Is this a good idea? Is there data available for the offset and gain error of the internal reference opamp (fig. 31 of datasheet)? Possibly these errors dominate the internal bandgap so this option can't be used.
If the option above can't be used I've got the following questions:
- Is the internal bandgap still powered when PD_REFBUF=0?
- Is there data available on the dynamic current draw on VREFP for high-resolution mode?
Thanks,
Koen
