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AMC3301: Schematic review

Jonathan Navor
Expert 7845 points
Part Number: AMC3301
Other Parts Discussed in Thread: AMC3330

Hi Team,

Good day! We need you help to check the customer's schematic. 

They are using AMC3301. Please check if the connections missed anything. OPAMP and reference IC are powered from the HLDO of the Isolator. 

Thank you in advance for the support. 

Best regards,

Jonathan

  • 0
    TI__Mastermind 47625 points

    Hi Jonathan,

    What type of application is this circuit going into? 

    I see that they are using an ADI opamp with extended temperature range, AD8479TRZ-EP, that operates from a minimum of 5V.

    Do we have an alternative TI opamp that we can offer here? 

    Our HLDO_OUT voltage is typically 3.2V, so this specification will not be met and is specified to supply up to 1mA over temperature. 

    The resistor on the negative input, R245 is not necessary in this configuration, but will not affect performance negatively either. 

  • 0
    Prodigy 65 points

    Hi Jonathan,

    Please suggest the part with higher common mode voltage, as our application need higher VCM

  • 0 in reply to Alexander Smith
    Prodigy 65 points

    Hi Alexander,

    I was using AD8479 before AMC3301 because that don't have higher VCM. As I can't use AD8479 now, please suggest some other OPAMP with higher VCM or any other isolation amplifier with higher VCM (common mode voltage).

    Alexander Smith said:
    extended
  • 0 in reply to Gokul Raj
    TI__Mastermind 47625 points

    Hi Gokul,

    Can you please share some information about the application? 

    Is this for a current or voltage measurement? 

    What are the expected isolation requirements? 

    Why is a high common-mode voltage required?

  • 0 in reply to Alexander Smith
    Prodigy 65 points

    Hi Alexander,

    This is for a voltage measurement

    Expected isolation requirement - Galvanic Isolation

    The voltage which we are measuring is coming from a battery, for protection we require op amp with high common mode voltage.

  • 0 in reply to Gokul Raj
    TI__Mastermind 47625 points

    Hi Gokul,

    I recommend using the AMC3330 with a resistor divider then. An additional amplifier with a high common-mode voltage should not be necessary.

    The AMC3330 is ideal for voltage measurements with high impedance resistor divider circuits and has with a larger input voltage range and higher input impedance compared to the AMC3301, which is primarily used for current measurements across low impedance shunt resistors. 

    The AMC devices themselves do not have high common-mode input ranges in the traditional sense. However the device has two grounds, high (HGND, pin 8) and low (GND, pin 9) side.

    The INP/N input common-mode input voltage rating is the inputs (pin 6/7) with respect to HGND (pin 8).

    The working voltage rating, is the maximum steady-state voltage difference between HGND and GND, 1.7kV_DC for the AMC3300. 

    Here is some collateral that may help: https://www.ti.com/lit/an/sbaa321/sbaa321.pdf

    https://www.ti.com/lit/an/sbaa553/sbaa553.pdf

    Please let me know if you have additional questions or would like a schematic review.