ADuM1250 connection @UG-304, Side1 or Side2?

ADM1075 input high level is 1.1V min and low level  is 0.8V max.

it is a little different from normal I2C, so Side 1 connection might be no problem.

but please tell us which is better.

moto

Hello Moto,

Side 1 of the ADuM1250 uses non standard levels as part of its flow of control scheme.  The ADM1075 also has non standard levels on its SCL and data lines.  So in this configuration I would recommend using Side 2 facing the ADM1075, since side 2 has standard CMOS output levels, there will be no issue detecting a low output.  Whether you can do this really depends on the details of what is connected to the isolated I2C bus and what its I/O levels are.

However, since you have a split data line, you have other options in the iCoupler line.  For example you could use the ADuM144x ultra low power device.  It will allow you to power from the 48V bus without squandering a lot of power.  The data line is split on one side, and the Data in and out can be combined on the isolated side with a tri state buffer to allow I2C bidirectional capability as shown in the diagram below.  This is for a POE controller, but the principle is the same.  This type of arrangement will work with a wide variety of our standard digital isolators.

I hope this gives you some help and options.

Best regards,

MSCantrell

Dear Mr. MSCantrell

Thank you very much for good idea and good answer.

And sorry for slow reply.

Main problem is only 01V difference of output/Input spec, I think.

How to work "Input/Output Logic Low Level Difference" of ADuM1250.

Is it a key to understand this device?

Regards

moto