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AMC1311-Q1: Application Question

Lanxi Li
Expert 6145 points
Part Number: AMC1311-Q1
Other Parts Discussed in Thread: AMC1311,

Hello team,

My customer is using AMC1311.

During their test, the input terminal (Vin) of AMC1311 may exceed 2V, almost 2.15V. However, after testing, there was no problem at all temperature ranges.

  • So they want to know what happens when the input terminal Vin is greater than 2V.
  • The specification says that under normal voltage, it should not exceed 2V, and under overvoltage, it should not exceed 2.5V. Please help check whether this understanding is right?

Best regards,

Lanxi

  • 0
    TI__Guru 50921 points

    Hi Lanxi,

    We describe a similar situation in this application note: https://www.ti.com/lit/an/slyt810/slyt810.pdf

    I've copy/pasted the section below. Beyond 90% of the V_Clipping voltage, significant nonlinearity can be seen, but up to 90% of V_Clipping, the device will continue to output linearly, however the accuracy is not specified. 

    "Notice that the resistance value from the ideal calculation to the closest standard value increased slightly, which results in a full-scale input voltage range that is larger than the linear full-scale input range of the isolated amplifier. This means that for full-scale current magnitudes, the resulting voltage magnitude will no longer be within the linear region of the isolated amplifier’s input. Isolated amplifiers often have an additional input voltage range beyond the linear input voltage range before they begin to clip. Within this region—typically as high as ±280 mV for ±250-mV devices and ±56 mV for ±50-mV devices—the accuracy of the isolated amplifier is not specified in the data sheet; however, the isolated amplifier will continue to output a voltage with accuracy similar to the linear region. This may be acceptable for some applications if the accuracy requirement of the maximum current magnitude is relaxed compared to the nominal measurements."

    Beyond 90% of the V_Clipping voltage (2.26V for AMC1311-Q1), significant nonlinearity can be seen, but up to 90% of V_Clipping, the device will continue to output linearly, however the accuracy is not specified. If this is an issue for the application, the sensing resistance can be reduced.