ADS8681EVM-PDK: so

Chen Alex1

Genius 3865 points

Part Number: ADS8681EVM-PDK
Other Parts Discussed in Thread: ADS8699, ADS8681, ADS8681W

Tool/software:

hi SIR

question 1:

I Got the ADS8681EVM & test the evb done, another plan is verity the ADS8699 performance.

may I exchang the ADS8699 to the ADS8681EVM?

ADS8681, ADS8699 only bit different?

question 2:

after change the ic, any firmware or hardware need modify?

question 3

I add the AC couple, that is right? as below figure

question 4:

below is the bandwidth of ADS8699, May I adjust the bandwidth?

2. how the hold the 15kHZ Maintain, no attenuation

question 5:

5. if you have any solution which bandwidth is wide than ADS8699, others is same

thanks

over 1 year ago

0 Tom Hendrick over 1 year ago

TI__Guru**** 181351 points

Hi Alex,

A1 and 2.) Yes, you can swap out ADS8681 for ADS8699, however the SW and GUI is only configured for 16-bit data. I'll check, but I don't believe we have a version of the GUI that supports 18-bits.

A3) What voltage range are you looking at? Why are you looking to do an AC coupled input?

A4 and 5) No, you cannot adjust the internal LPF frequency, it is fixed at 15kHz. There is a recently released ADS8681W which has a wider bandwidth (450 kHz) LPF, also fixed.

0 Chen Alex1 over 1 year ago in reply to Tom Hendrick

Genius 3865 points

A3) What voltage range are you looking at? Why are you looking to do an AC coupled input?

Input range：+/-10V 和 +/-2.5V,

input have the DC offset, we would like to in serial to a cap to reduce the DC value

after Add the cap, Will it cause sampling error to adc?

0 Tom Hendrick over 1 year ago in reply to Chen Alex1

TI__Guru**** 181351 points

No, it won't impact the ADC sampling. You won't need the cap on the AIN_GND side.

0 Chen Alex1 over 1 year ago in reply to Tom Hendrick

Genius 3865 points

hi Tom

when I remove the cap in the ADIN_GND, I will get the offset value,

If add the cap in ADIN_P and ADIN_GND, The offset is Zero

Did you have any AC couple guide for me?

thanks

0 Tom Hendrick over 1 year ago in reply to Chen Alex1

TI__Guru**** 181351 points

Hi Alex,

I don't have anything specific on AC coupling. If adding the cap to AIN_N gives you the result you are looking for, you can leave it in the circuit.

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ADS8681EVM-PDK: so