Other Parts Discussed in Thread: REF5025, ADS1282, LM27762, ADS1261EVM, ADS1278, ADS1281, REF5050, OPA725, OPA837, TIDA-01055, OPA625
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Are you using the REF5025 and the OPA735 to power the AVDD and AVSS supplies of the ADS1282?
You might be able to use to this circuit as a supply voltage, but I'd be concerned that the REF5025 may not be able to supply enough current to the ADC, as it really is only able capable of sourcing about 10mA of current. I would recommend looking into using the LM27762 to generate the +/-2.5V supplies. I've used this circuit on the ADS1261EVM for just this purpose:
In your current configuration, the 2kOhm resistor on the AVSS supply might be causing problems. I know it may be necessary to stabilize the opamp for any capacitive loads on AVSS; however, this resistance may be too much for the AVSS supply.
thanks for your reply.
Frist， the +2.5VREF and -2.5VREF just for the reference voltage of ads1281，i used another chip to get + 2.5V and -2.5V for AVDD and AVSS.
Second，i had replaced the R06 with 0Ω，but the problem still exist.
I can't find the current information about reference on datasheet of ads1281/1282，i think the current is very low......
Thanks for your reply.
I agree with you about the voltage ripple is caused by the ADC perform conversion. thanks for your explanation for this.
I had replaced the R06 with 0Ω，but the problem still exist.
if i used the REF5025+OPA735 to get +2.5V and -2.5V , the voltage very stablely and high precision，2.5000xxV and -2.4999xxV. I am not sure the figure 65 on page41 of http://www.ti.com/lit/ds/symlink/ads1282.pdf will get same effective .The VREFN connect to the AVSS, but the -2.5V of the AVSS maybe this will generate another problem(noise or ...) for high resolution data acquisition system. just my opinion, didn't test.
In my design，I used differential voltage input.
if your have another reference circuit ，please send my emai：email@example.com