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AMC1302-Q1: High side current sensing confusion

Gary Jiang
Intellectual 980 points
Part Number: AMC1302-Q1
Other Parts Discussed in Thread: AMC1302,

Hi,

As the datasheet of AMC1302-Q1 describes, the AMC1302 can be used for high-side current measurement. So the common-mode voltage of AMC1302 should be up to the high-side line voltage at least, right?

But the Vcm range of AMC1302 is from -0.032V to (VDD1-2.2)V, why it can be used for high-side current measurement? 

  • 0
    TI__Guru**** 174620 points

    Hi Taoran,

    The common mode input voltage to the AMC1302 cannot exceed the supply voltage.  You would need to create a floating supply source to use the AMC1302 in a high side measurement application.

  • 0 in reply to Tom Hendrick
    TI__Intellectual 980 points

    Hi Tom,

    What is a floating supply source? Does that means the ISO_GND is physical isolated from the high voltage GND? If then, how can the amplifier determain the input common-mode voltage?

    Does the high side voltage will create a common mode voltage on all the pins of the AMC1302, so the common mode voltage will be insignificant?

    Thanks.

  • 0 in reply to Gary Jiang
    TI__Guru**** 174620 points

    Hi Taoran,

    If you take a look at the first page of the AMC1302 datasheet, there is a schema showing the 'floating power supply' which is not included in Figure 52.  The assumption here is that you have gate drive voltages that could be tapped for creating the VDD1 supply.