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ADUM2250 problems

Question asked by hhachem on Feb 1, 2013
Latest reply on Jul 17, 2017 by DStracke

Hello,

 

I'm an intern at Philips in Aachen Germany. I received a PCB a month ago to troubleshoot/repair. The PCB has major design errors, I was able to repair most of them so far. 8 ADUM2250 are on board. By reading the datasheet, I noticed that the sides of the ADUM2250 differ from one another, i.e. side 1 is I2C compatible while side 2 is I2C compliant. The ADUMs on board are connected in such way that side 2 is the input and side 1 the output. How critical is this?

I managed to connect one of Isolators as described in the datasheet and cut the I2C from the rest, butthe I2C signals coming from a microcontroller seem to get distorted once I connect the I2C bus to the ADUM. The following images should explain what I mean:

 

I2C SDA when MCU not connected to ADUM

 

IMG_20130201_160706.jpg

 

I2C SDA when MCU is connected to ADUM:

 

IMG_20130201_115806.jpg

 

ADUM's output SDA looks even worse than the input! Any idea why this is happening?

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