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AMC1302: LPRF Current Sense Techniques

Zebryk
Expert 1240 points

Part Number: AMC1302
Other Parts Discussed in Thread: CC1120, AMC1301

Hello,

I am working on an isolated current amplifier application for LPRF transceivers.

(Currently looking at the AMC1302 Amplifier but am open totally to better ideas.)

What happens beyond the specified input voltage of +/-50mV?

Does it just become saturated or does it blow up catastrophically?

Is there a better part for measuring the entire current range of RF Parts like the CC1120 from deep sleep to max power?

(Deep Sleep: 0.12uA to TX Max: 45mA)

Any App Notes on dealing with this challenge?

Peace,

Jay Zebryk

  • 0
    TI__Guru 56792 points
    Hi Jay,

    Thanks for your post!

    The output will become saturated as you indicated.

    If you take a look at pg4 of the datasheet you will see the Absolute Maximum Ratings, as well as the Recommended Operating Conditions tables.

    The output will begin to clip around ~64mV and you will not see failure until the Absolute Maximum Ratings are surpassed, VDD1+0.5V or GND1-6V. Additionally, I would not expect a catastrophic failure so much as burning up the device.

    Many of our devices support +/-250mV input ranges such as the AMC1301. What kind of resolution are you looking for here?

    I do not believe that we currently have an app note covering this topic, however there is a plan to address this issue in the near future!
  • 0 in reply to Alexander Smith
    Expert 1240 points

    Alex,

    To be clear, absolute Max means the part is ruined?

    The range of interest, for example with the CC112x, is as follows:

    TX @ 434MHz : 50mA @+15dBm (50mV Across 1 Ohm)

    Power Down w/Retention: 0.12uA (0.12uV Across 1 Ohm)

    I am looking to build a general purpose current measurement device suitable for all LPRF transceivers.

    Would the AMC1302 be too sensitive to transients and subject to failures?

    Would the AMC1301 provide sufficient gain/resolution to make accurate measurement of "Sniff Mode" operation?

    FYI, this is for R&D, not for a production unit so the cost to build does not matter much.

    (Except that commercial units that do this cost $10K+!)

    Can you suggest a better solution for measuring/recording LPRF current profiles?

    Thanks,

  • 0 in reply to Zebryk
    TI__Guru 56792 points
    Jay,

    Correct.

    This depends on the magnitude and duration of transients that you expect to see. Violating the absolute maximum ratings magnitude does not mean that the device will fail instantaneously, there is the time component to consider as well.

    This depends on your resolution target. Can you clarify what you mean by "Sniff Mode"? Meaning that you check in on the channel periodically?