Other Parts Discussed in Thread: REF5025, REF2125, ADS1294
First the fundamental problem: I run a battery-driven system (very compact) with the ADS1294R for respiration detection at effectively 10Hz. In order to reduce the power consumption I turn the ADS on when a measurement has to be done and then off again. This only works with an external reference because the internal one requires at least 150ms startup time.
The external reference shall also not draw too much power but shall provide a noise level low enough for a sufficient measurement - the critical part is the 1/f-noise at freq. <1Hz. ADS129xR datasheet tables 1 and 2 provide noise information for at least 1k samples - but for 32ksps this means only 31ms and for 500Hz a 2sec measurement period. Hence, this information is not suitable if I want to go into respiration detection.
Of course, before carrying out first tests with an external reference I also used the internal one which - surprise, surprise - did lead to good results.
What I'd like to have is a simple information regarding the noise level for 0.1-10Hz and e.g. 10Hz-10kHz for the internal reference to have a data basis for a proper external reference circuit design.
Thank's in advance.