ADS1298 Isolation of SPI I/F for Medical Instrumentation

Sadanori Kato

Other Parts Discussed in Thread: ADS1298

Hi,

Is it possible to use ISO7141 to isolate the medical instrumentation(ECG, EMG and EEG) with the SPI interface if ADS1298 is used ?

Best regards,

Kato

over 9 years ago

0 Brian Pisani over 9 years ago

TI__Mastermind 38745 points

Hey Kato,

I don't see any reason why not. Be careful with timing on the interface, though. This isolator looks like it could delay signals up to 35 ns which means that you will have to have at least that much time in between the hold time of output of the master and the setup time on the input of the master for each half SCLK cycle. This will allow for MISO signals to propagate all the way back to the master before the master's hold time begins.

Regards,
Brian Pisani

0 Sadanori Kato over 9 years ago in reply to Brian Pisani

Guru 36540 points

Hi Brian-san,

Thank you for explaining so politely.
I have an additional question.
Could you please tell me the value of HBM, CDM and other parameters which is needed to isolate the medical instrumentation(ECG, EMG and EEG) if you know ?

Best regards,
Kato

0 Brian Pisani over 9 years ago in reply to Sadanori Kato

TI__Mastermind 38745 points

Hello Kato-san,

This device is qualified with an ESD rating for both HBM and CDM, but I am not aware of what specifications are needed for medical devices. You can find the ratings on page 12 of the datasheet for reference.

Regards,
Brian

0 Sadanori Kato over 9 years ago in reply to Brian Pisani

Guru 36540 points

Hi Brian-san,

Thank you for your quick reply.
I will consult it to our colleagues and your local office FAE.

Best regards,
Kato

0 Kevin Kreger over 8 years ago in reply to Sadanori Kato

Expert 1020 points

Hi Kato-san,

Were you able to use the ISO7141 or did you go to a faster part?

Thanks for your help,

Kevin

0 Sadanori Kato over 8 years ago in reply to Kevin Kreger

Guru 36540 points

Hi Kevin-san,

I have suggested ISO7141 to our customer as below.
ISO7141 is able to be used as the isolation of the SPI I/F for ADS1298.
However, please design the timing of SPI I/F considering the propagation delay and the output skew and etc between channels.

Best regards,
Kato

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ADS1298 Isolation of SPI I/F for Medical Instrumentation