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ADS1298 lead-off

Kai Hsiao
Guru 12675 points
Part Number: ADS1298

Dear Sir 

I saw ADS1298 support 3 method lead-off detect measurement 

RLD / DC / AC

May I know

1. which method one is the popular in this ECG market 

2. Do you know which detect as blow discrete solution ?? RLD ??

3. If we want to convince customer to change ADS129x ,do you think lead-off is a key point ??

Thanks  

  • 0
    TI__Mastermind 38745 points

    Hello Kai,

    1. I can only tell you about what I've seen with the ADS1298 since that is the solution I am most familiar with. For that device, using the internal DC current sources to detect high impedance connections is the most popular and effective way to detect lead-off.
    2. This method seems to use pull-up/down resistors to change the voltage at the inputs. R33 or R45 will pull the input voltage up or down when the respective electrode impedance becomes too large which will create a large voltage at ECG_LEAD_OFF. Then there must be some threshold that when the voltage exceeds it either positive or negative, the processor indicates it to the user.
    3. I think the integrated lead-off detection is part of the reasons the ADS1298 is so attractive. That chip contains a lot of different functions that make it very integrated. Instead of using the 3 different amplifiers they have even on this screenshot, they could condense it down to the ADS1298. It will make the design simpler. The ADS1298 also has great performance specs on the core signal chain which make it an even more attractive solution.

    Regards,

    Brian Pisani