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AMC1400-Q1: AMC1400-Q1:

Bheemashankar Y
Prodigy 10 points
Part Number: AMC1400-Q1
Other Parts Discussed in Thread: AMC1400

Tool/software:

Dear TI Support Team,

I hope this message finds you well.

 

I am currently working with the AMC1400-Q1 and have attached a reference schematic featuring three different configuration schemes (Scheme 01, Scheme 02, and Scheme 03). I would appreciate your guidance on the following points:

             Scheme Comparison:

  • Scheme 01: This configuration follows the recommendations from the datasheet, kindly confirm if this is the preferred or officially recommended setup by TI?
  • Scheme 02: This is the configuration I am currently using in my design, Is Scheme 02 endorsed by TI? Are there any known issues or potential drawbacks with this approach?

              Input Adjustment for 100 mV:

  •  I am aiming to configure the input for a 100-mV differential signal, With the current resistor values (R14 and R15), I’m observing a voltage slightly above 100 mV,

              Is it possible to fine-tune the input to achieve exactly 100 mV by placing a resistor in parallel with R14 and/or R15?

  • Could this be done with a single resistor, or would a resistor divider network be more appropriate?,

             Your guidance on the best method to precisely set the input voltage would be highly appreciated.

              Scheme 03 Evaluation:

  •   Scheme 03 represents an alternative layout. Could you please advise if this configuration is acceptable from TI’s perspective?
  •  Additionally, how does Scheme 03 compare to Scheme 01 and Scheme 02 in terms of performance, accuracy, and safety?

              Capacitor Value Change:

  •  The current design utilizes a 10 nF capacitor. Would it be acceptable to replace this with either a 22 nF or 47 nF capacitor?
    Could you please explain the impact this change would have on bandwidth and filtering characteristics? 

                I would be grateful for your expert advice and recommendations on these points to ensure the reliability and performance of the design.

 

             Thank You!

  • 0
    TI__Intellectual 2541 points

    Hello,

    it seems that you're doing voltage measurement with the AMC1400. This device is by default a current sensing device with the input of +/- 250mV. I suggest better using a voltage sensing device, if possible.

    Does your system need the AMC1400 package?

    Voltage sensing devices have very high input impedance (1G) due to the buffering of the input. Current sensing devices have rather low input impedance, in the range of 10s of kilo ohms (but they work with way lower signal amplitudes). This means the input impedance loads the high voltage resistor divider. This is what you need to consider when working with the part.

    10 ohm resistors in series with INP and INN pins improve the AC performance of the IC. The combination of 10 ohm / 10 ohm /10 nF is something we generally start with when working with this device. The improvement is typically visible in the frequency domain (FFT).

    In principal, all three configuration will work as long as you don't violate the common mode voltage VCM .

    You could fine-tune the resistor divider using a parallel resistor. I would work with a calculator such as: https://www.qsl.net/in3otd/parallr.html

    that gives you a combination of resistors (series or parallel) based on the desired value.

    Regarding the capacitor - 22nF will be likely fine. Our component proposals typically come from the test setups we used for evaluation and validation of the part, as we are not able to test that many various combinations. I personally do not expect any performance change with 22nF.

    Kind regards,

    Jiri