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Data converter and instrumentation amplifier

ArTzy
Mastermind 20020 points

Other Parts Discussed in Thread: INA828

Hi Experts,

Good day. I have two questions from client as follows:

1. TI e-book "Analog Engineer's Circuit Cookbook: Data Converters", on page 24, there is a LINK to a calculator on TI's website, which is broken. Is this has an updated link? The tool is for verifying common-mode input range for some TI amps like INA828.

2. Beyond the common mode input range, client is looking at using it an an application where its power supplies could be either at 0V, or floating, but interfaced with some external voltage. From the datasheet section 7.3.4, this part has input protection FETS (PFET?) that can limit input current to 8mA. It seems like the input diodes can safely handle the 8mA and will shunt to +Vs and -Vs. Section 7.3.4 talks about if +Vs and -Vs are not able to sink current, then to use an external zener diode. Assuming  this is to protect the super beta input stage transistors - the question is what voltage can they handle before being damaged? This will help him select appropriate zener diode the right diode, or we might recommend one.

Any thoughts on these?

Hoping for your guidance.

Thank you!


Regards,
Archie A.

  • 0
    TI__Guru* 77501 points

    Hi Archie,

    Q: ... on page 24, there is a LINK to a calculator on TI's website, which is broken

    This part has been consolidated into Analog Engineer's Calculator now, see the link below. 

    https://www.ti.com/tool/ANALOG-ENGINEER-CALC?keyMatch=ANALOG%20ENGINEERS%20CALCULATOR

    Q: the question is what voltage can they handle before being damaged? This will help him select appropriate zener diode the right diode, or we might recommend one.

    If input overvoltage is able to clamp by zener (if ps is unable to sink current) up to +/-40V per the datasheet's absolute max. rating, the INA828's inputs will be safe. The important part of input protection is to limit the input current up to approx. 8mA, if the overvoltage conditions are occurred. 

    If you have additional questions, please let me know. 

    Best,

    Raymond