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AMC1106M05: acceptable voltage on input pins

Zahra Derafshi
Prodigy 10 points
Part Number: AMC1106M05

Hi,

I'm looking at the datasheet for AMC1106x and in the typical application section it shows that the shunt resistors can be connected to the hot lines.

Also in the datasheet mentions that the voltage that can be on input pins of the IC is couple of volts.

I was wondering if I can put the shunt resistor on the hot side with voltage of 48V or 240v bus or it has to be on the low side? 

Thanks in advance

  • 0
    TI__Mastermind 22950 points

    Hi Zahra,

    The shunt can be placed on the hot side but care needs to be taken to ensure the common mode is in the appropriate range according to the data sheet specifications. I have taken another image from the data sheet and will explain the recommended setup. 

    The attached image shows this a bit more clearly but essentially, in order to meet the common mode range spec, AVDD should be left 'floating' and be connected to the user side. Additionally, GND should be connected to the bottom of the shunt. With AVDD isolated, Vin is 3.3V to 5V relative to the bottom of the shunt resistor and this allows the input range to stay within +/- 250mV. 

    Regards,
    Aaron Estrada

  • 0 in reply to Aaron Estrada
    Prodigy 10 points

    Aaron,

    Thanks for getting back to me on this. I understand when you say AVDD should be left "floating" , but what do you mean by "and be connected to the user side"? Do I leave it floating or connect it somewhere?

  • +1 in reply to Zahra Derafshi
    TI__Mastermind 22950 points

    Hi Zahra,

    Apologies for any confusion here. AVDD should be sourced by it's own isolated power rail ie a cap-drop supply or an isolated transformer winding. If you have multiple AMC's, each AVDD supply would be isolated from each other have each AVDD would have their own isolated power rail. 

    I hope this is a little more clear!

    Regards,
    Aaron Estrada

  • 0 in reply to Aaron Estrada
    Prodigy 10 points

    Thanks so much Aaron, this helps. I appreciate your support here.

    Regards

    Zahra Derafshi