Hello,
I'm trying to build a reflectance-based oxygen saturation probe using your AFE4490 device.
Unfortunately, I'm having a bit of trouble using the datasheet (May 2013) as it doesn't match up with your evaluation module schematic (Feb 2013).
Page 11 of the datasheet labels pin 9 as 'TX_REF' and says simply 'TX Reference Voltage', without giving any details as to how it should be connected etc.
However, in the schematic on page 46 of the evaluation module's manual, this pin is named RSVD and is connected to ground via a 2.2uF capacitor, just as the bandgap reference pin 7.
How should this pin be connected for reliable function?
Also, if I have no intention of ever resetting the analog front end of the device independently, should I tie the RESET pin (number 29) high (digital supply), or can I leave it floating?
May I also ask why you decided to name the SPI chip select pin 'SPISTE' (without a bar indicating active low) rather than CS?
Many thanks,
-Rob Learney.
