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AMC1301: AMC1301

Kunal Pathak
Intellectual 375 points
Part Number: AMC1301
Other Parts Discussed in Thread: AMC3330, AMC1311

I want to measure Line to line voltage (415V) and for that, I am using AMC1301 since it has. I have selected the Specified linear differential range (VFSR) to be -230 mV to +230 mV. However, I am unable to get the proper differential output voltage and also the input voltage to AMC1301 is not proper. So, can you help me and suggest where I am going wrong?

  • 0
    Guru 140200 points

    Hi Kunal,

    you are violating the common mode input voltage range of AMC1301:

    Kai

  • 0 in reply to kai klaas69
    Intellectual 375 points

    Hi Kai,

    Is there any solution through which I can avoid violating the common-mode input voltage range.

  • 0 in reply to Kunal Pathak
    Guru 140200 points

    Hi Kunal,

    where are VG1 and VG2 coming from? Can you give some more details on your application?

    Kai

  • 0 in reply to Kunal Pathak
    TI__Mastermind 47595 points

    Hi Kunal,

    If you see the first page of the datasheet, you will see that GND1 is tied to VINN. This ensures that the input signal is within the common-mode input range, as VINP can swing +/-250mV with respect to VINN and GND1. VINN and GND1 will track the input voltage.

    However, as Kai has pointed out, you also have to ensure that the power supply VDD1 is tracking (or floating with) the input voltage as well when wired in this configuration. This becomes a system level discussion, hence the need for additional information. 

    As always, thank you for the help Kai! 

  • 0 in reply to kai klaas69
    Intellectual 375 points

    Hi Kai,

    VG1 and VG2 are phase voltages having 325V peak voltage and they are 120 degrees apart.

    VDD1 is connected to 5V dc supply similarly VDD2 is connected to 3.3V.

    I want to measure the line to line voltage with AMC1301. So, according to you how should I do that in order to avoid common-mode input voltage violation?

  • 0 in reply to Kunal Pathak
    TI__Mastermind 47595 points

    Hi Kunal,

    Where is VDD1 derived from? Is there any flexibility in terms of where VDD1 is derived from? 

    Oftentimes, one device is used to measure each phase with a floating supply, such that the high side of the device tracks the phase voltage. Ensuring that everything is within the common-mode range for phase to phase measurements is sometimes a challenge. 

    Furthermore, I would recommend using a device with a higher input impedance for voltage measurements such as the AMC1311 (0-2V input range) or the AMC3330 (+/-1V input range, single-supply). Using a device with low input impedance such as the AMC1301 can lead to gain errors on the output depending on how large your sense resistor is.