We are designing a system with 8 ADS1298 converters in BGA.
A few quick questions.
1. Is there a plan to release the ADS1299 in the BGA package? We prefer the lower noise of the ADS1299, but need the smaller form factor to fit 8 devices.
2. We would like to make the smallest layout of 8 ADS1298 parts as possible, with as few components as possible. Can the capacitor on the WCT output be omitted if the WCT amps are not used?
3. Can any of the other capacitors be omitted?
4. We would also like to minimize the number of external connections required to operate the system. Is the reset line required to be toggled at power up? It seems that reset through the SPI command command would be equivalent. Is this correct?
5. Can the ADS1298 generate an in-band AC excitation signal for lead-off detection? We would like to measure the electrode impedance, similar to the feature on the ADS1299.
6. What is the minimum number of external connections when using several ADS1298s? It seems that SCLK, DIN and DOUT are required. DRDY seems helpful, though if deterministic, it could be inferred. In the daisy chain mode, it seems that we could use just two CS signals, one for the master ADS1298 (which would have the RLD enabled) and another CS for all 7 other ADS1298s.
7. Can conversions be synchronized using the start pin without sharing an external clock? For example, in systems where the 2 MHz clock cannot be routed to all the ADS1298 chips?
Thank you!