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Question asked by samisivic on Oct 7, 2016
Latest reply on Oct 20, 2016 by MSCantrell

I am implementing an application with PIC32 as I2C Master and PIC16F18325 as slave. The supply for PIC32 is 3.3V and for PIC16 is 5V. In PIC32 master side I am using PCA9515 i2c buffer from Texas Instruments and at the pic16 slave side ADuM1251 from Analog Devices as shown in the figure below.



I am facing an issue while receiving data at the master side. While receiving data from PIC16, there is an offset of about 0.9V on sda line at the input side of PCA9515 i2c buffer. The same signal is also measured at the output side of PCA9515 i2c buffer and it is logic high (i.e. 3.3V). But the signal must be logic low level. The screenshot of the oscilloscope is also given.


As a solution to the issue, I removed ADuM1251 from the circuit and the issue is solved. But I don’t have any idea why it does not work with ADuM1251. I have read the data sheet of both ADuM1251 and PCA9515 and didn’t find any reason.


Could anyone help me solving this issue.