I am working on a medical device design that ideally would use the ADAS-1010, but for reasons related to size and power, and trying to provide mostly the same measurement set using 2 ADAS-1000s.
So I will need to add circuitry to buffer and sample 3 invasive blood pressure channels and two YSI thermister compatible temperature sensors. I would like to use one device if possible to buffer and amplify (even better if there was a solution to buffer/amplify and ADC the (5) inputs which have very low sampling rate requirements (~150hz).
My question is whether the AD7124-8 would fit the bill or is there another device that someone could recommend. I found a similar invasive blood pressure acquisition schematic but haven't found many examples as most people think non-invasive blood pressure when they think BP, and I need invasive blood pressure (and temperature) interface circuit.
Any thoughts would be most appreciated!
the AD7124-8 would suit the application. I recommend the AD7124-8B as its internal reference has a tempco of 10 pppm/'C max. The part can support 8 differential inputs so can accommodate the 3 pressure sensors and the 2 temperature sensors. An FS value of 5 in full power mode, sinc4 filter gives a throughput of 183 sps. The part provides gains from 1 to 128.A ratiometric configuration can be used for the pressure sensors as per the diagram you included in your post. This will give optimum performance. For the thermistors, the excitation currents can be used to supply the thermistor. Just ensure that the max thermistor resistance for your design x exc current still meets the compliance spec of the exc current. Another option is to use the internal reference to supply the thermistor. A precision resistor in series with the thermistor can be used to measure the current through the thermistor. The AD7124 current will be about 1mA - is this sufficiently low? The package is 5 x 5 mm and the package height is 0.95mm. Is this sufficiently small?
Thanks much! Yes, 5x5 mm would be adequate, especially if this one device could supply basically everything that the '1010 would offer with the exception of non-invasive cardiac output, which I dod not currently need.
Hi All,Moving this thread to Precision ADCs, so that people with the same question can easily see this thread.Regards,Goz