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AMC1100 max Differential input voltage

Idan Ozana
Intellectual 480 points
Other Parts Discussed in Thread: AMC1100

Hi,

In my application I need to measurement the load current from 300V/4A isolated power supply. For that purpose, I'm wanted to use the AMC1100 Fully-Differential Isolation Amplifier in a High-Side measurement configuration (with floating5V power supply, VCC1). Before I'm implementing the circuit in my custom board, I need you to answer the following questions (which probably related to the same subject):  

    1. According to the datasheet, the maximum input voltage before clipping is 320mV. Assuming that I have a 50mΩ shunt resistor, the max load current allow, even the momentary at startup of the 300V power supply, is 320mV/50mΩ=6.4A. My question is that: what is the maximum VINP – VINN voltage before damaging the devise? How can I see that from the datasheet?
    1. Again, Assuming that I have a 50mΩ shunt resistor, since the common-mode operating range is from –0.16V to VDD1 (5V), the device will not damage up until the 5V/50mΩ=100A (VINP – VINN will be 5V) Am I right?

Thanks a lot,

Idan

  • 0
    TI__Guru**** 181001 points

    Hi Idan,

    Thank you for your interest in the AMC1100!  

    For your first question (s), you can look at the Absolute Maximum Ratings table on page 3 of the AMC1100 datasheet.  The analog input voltage at VINP or VINN can be as low as -0.5V or as high as VDD1 +0.5 V.  Since the supply voltages can be as high as 6.0V, the extreme limits would be 6.5V - (-0.5V) or 7.0V max differential.

    As you already noted, the outputs of the AMC1100 will clip with voltage on the input above 320 mV.  If you were to have 100A across your 50 mΩ shunt, the resulting 5V input would not damage the AMC1100 but the outputs will be saturated.