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Daisy Chaining ADS1299 Eval Boards

Carson Hammoser1
Prodigy 90 points
Other Parts Discussed in Thread: ADS1299

Daisy Chaining ADS1299 Eval Boards

Hi,

We'd like to get a better idea of the noise levels when 2 or more converters are cascased (single GND ref.), as there are no specs for this mode (only differential), and the ground lead to ADC input lead capacitance will increase with more channels.

I was reviewing the documentation for the ADS1299 EVM and what is required to daisy chain 2 boards with the one control board (MMB0). If this is possible we'd order a 2nd board. Beside using the DAISY_IN pin, there may be more changes required. I noticed is that there is an EEPROM (U10) mounted on the ADS1299EVM which connects to MMB0 board. Would I need to change the address of this EEPROM on the 2nd board (via R71, R72, R73). Or can I simply leave it disconnected on the 2nd board? Also, what changes to I need to make on the GUI control interface?

Thank you,

Carson

  • 0
    TI__Guru**** 181641 points

    Hi Carson,

    You can potentially daisy-chain two (or more) of the ADS1298ECG-FE boards together, but you'd have to do it through J5 and JP-5 on the eval board (schematic is in the Users Guide).  Our GUI/Software does not support daisy-chain mode, so you would need to write something up on your own host processor.

    The EEPROM contains assembly data - as in when our board shop made/tested the EVM.  If you were to write your own code, you could program it as you like or simply ignore it all together - the I2C address on your two boards would be the same, so you'd have to change address to use both.

    Noise wise, your original question, there should be no additional 'noise' as you add more devices to the mix.  Taking any layout oddities into account, the two or more devices on your board should meet all data sheet specifications as if they were stand alone devices.