AMC1304M25: AINP/AINN referenced from AGND?

Hi A Gir,

For the AMC1304, the normal input range on AINN and AINP is +/-250 mV referred to AGND. The input common mode voltage can be as high as 1.2V above AGND or 32mV below AGND. So, no - the inputs cannot 'float' and they should not be allowed to exceed the Absolute Maximum voltages (relative to AGND) specified in section 7.1 of the datasheet.

By AVDD, I suspect you are actually referring to LDOIN (pin 6). Internal to the AMC1304, there is a Low Drop Out DC/DC converter. The LDO input can be as high as 18V referred to AGND. This node supplies the input amplifier section of the AMC1304 with 3.45V (the voltage on the VCAP pin).

Hello

Yes I want say LDOIN (Pin 6).

So, the AMC1304 on my board should be broken! My DCBus was about 30V while the LDOIN was 15V fixed....

So If I understand I have following solution:

- Use the floating voltage generated on the gate with a capacity to drive the Upper side Mos (Should provide 6,5mA Max to the LDOIN) : Inconvenant: At least the lower gate must be driven a short time to load the capacity and then provide the power to the  LDOIN before make a "zero offset" calibration (like done on the IDDK exemple

- Like the IDDK eval board, use a DC/DC converter to power the LDOIN -> My Zero calibration can be done even if Gate never driven, but this is an overcost and  take place on PCB

- Use the proposed solution with SN6501 but this is an over cost and take place on the PCB.

So we chosen the AMC1304 because the total cost to measure the current was less than a LEM solution, but if we need add DC/DC or SN6501 based solution, I do not know what is the advantage to keep the AMC1304 solution vs the LEM?...

Yes If you want.

But I can't find a "private message" access on this forum?

Regards