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AMC1300: Design Support Request

Kazuki Itoh
Genius 9165 points
Part Number: AMC1300
Other Parts Discussed in Thread: AMC1311

Hello,

Could you please support my customer?

1. He didn't observe expected output voltage when INN and GND1 is isolated. When he connected it with resistor, it worked. Is this connection necessary?

2. He is going to divide the max. 50V signal to 250mV with 20kOhm and 100Ohm resistor divider. Could you please comment if it is good?

Regards,

Itoh

  • 0
    TI__Guru**** 168435 points

    Hi Itoh-san,

    Without seeing the connections or having details on what the input voltage was or how the outputs behaved, I suspect you might have been facing common mode input voltage issues.  The AMC1300 does not absolutely have to have AINn (or AINp for that matter) tied to GND1, but you do have to have both nodes properly referenced to GND1 in order to maintain the specified input common mode voltage levels.

    The AMC1300 is designed for use with low value shunt resistors (i.e. sub ohm), so while the 20K and 100 ohm resistors will give you 248mV at 50V input, you will still see some offset and gain error caused by the 100 ohm resistor.  I would rather see you use the AMC1311 with perhaps 24K and 1K