• State TI Thinks Resolved
  • Locked Locked
  • Replies 3 replies
  • Answers 2 answers
  • Subscribers 51 subscribers
  • Views 220 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

OPA192: e-trim offset removal circuit

Joey Christ
Intellectual 2260 points
Part Number: OPA192
Other Parts Discussed in Thread: OPA4192,

OPA4192 Op Amps have an "e-trim" offset removal circuit. 

  1. How permanent is this circuit (does its effectiveness age)? 
  2. What is the impact if this "e-trim" circuit fails?
  3. OPA4192 Op Amps have protection diodes on the inputs, which normally would be a problem for a buffer driven by a mux, although the datasheet says this part overcomes the normal limitations with a "unique" feature.  Is this "unique" feature understood and are there any potential undesirable impacts? 
    1. Does Figure 56 of the datasheet indicate the settling time will be longer if the protection feature is engage (vs Figure 40/42)?
  • 0
    Guru 140200 points

    Hi Joey,

    1. https://e2e.ti.com/blogs_/archives/b/precisionhub/posts/ic-long-term-stability-the-only-constant-is-change

    2. Why should the e-trim circuit fail? The e-trimming is performed at the end of fabrication process. Only OPAmps are sold which successfully run through the e-trimming.

    3. Why not having a look into the appnotes?

    https://www.ti.com/lit/an/sbot040c/sbot040c.pdf?ts=1658279005825

    Kai

  • 0 in reply to kai klaas69
    TI__Guru 60610 points

    Adding to Kai reply, etrim package level trim is done at the final test by adjusting the input offset voltage and drift with binary-weighted trim network by blowing poly links with high current pulses - this permanently opens them up after which final fuse is blown that prevent any future inadvertent re-trims (see more detailed description below). 

    OPA4192 is MUX-Friendly input op amp, which means it does NOT have back-to-back input protection diodes between input terminals - see below.

  • 0
    TI__Guru* 93105 points

    Hi Joey,

    Kai has thoroughly addressed your questions about the OPA192 e-trim. Please do have a look at the references he provided. I've added a few additional comments to your questions:

    1. How permanent is this circuit (does its effectiveness age)? - e-trim is TI's very modern, most advanced trim technique. Instead of laser trimming a thin-film resistor which can undergo minor shifts over time due to aging, e-trim electronically programs and permanently establishes the offset null mechanism. The programming is not affected by time.
    2. What is the impact if this "e-trim" circuit fails?  - The likelihood of the e-trim circuit is on par with the remainder of the rest of the op amp's silicon failure rate and extremely low. 
    3. OPA4192 Op Amps have protection diodes on the inputs, which normally would be a problem for a buffer driven by a mux, although the datasheet says this part overcomes the normal limitations with a "unique" feature.  Is this "unique" feature understood and are there any potential undesirable impacts? - It is certainly understood by TI and was specifically developed to overcome the issues associated with conventional input clamping discussed in the OPA192 datasheet Section 8.3.1 Input Protection Circuitry.
      1. Does Figure 56 of the datasheet indicate the settling time will be longer if the protection feature is engage (vs Figure 40/42)? - The OPA192 performance is the green line in the graph. The result is apparent.

    Regards, Thomas

    Precision Amplifiers Applications Engineering