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TPD4E1B06: ESD protection with very low leakage current

user5329941
Prodigy 100 points
Part Number: TPD4E1B06
Other Parts Discussed in Thread: LMP91200,

Hi,

I am designing a medical-grade pH meter that needs to pass the Level 4 ESD test. The pH electrodes have very high internal resistance, so the op amp must have a very low input bias current (the LMP91200 has an input bias current of less than 1 pA). Can you recommend any ESD protection solutions for such applications? ESD with lowest leakage current is TPD4E1B06 but still this current is an order of magnitude higher than the input bias current of the op amp

I am considering placing a large value pulse-withstand resistor (10 MΩ) in series with the input and a 100 pF capacitor to ground. Additionally, I plan to add a low leakage current TVS diode between the guard ring and ground.

I would be very grateful for any advice.

Mateusz

  • 0
    TI__Expert 5460 points

    Hi Mateusz,

    We do not have any devices with a leakage current below 1pA (nor am I aware of any solution on the market that can support this). It looks like the supply current is ~50uA, which would be an application we could support with our devices if there was an interest here.

    In addition, the LMP91200 does have some internal ESD protection (shown below). Would this internal protection be sufficient for your target protection level, or is external protection required to reach your target protection level?

    Best Regards,

    Josh Prushing