IMX6SOLOX_I2C backdrive

[victorafanasiev]

In my board, based on the MCIMX6X2AVN08AB microprocessor, I use the real time clock PCF2129T connected to an I2C interface of the microcontroller. The real time clock PCF2129T uses a lithium battery as uninterrupted power source. The lithium battery presents while the system is powered down.  Is it needed to use some bus isolation circuit to prevent back drive from the lithium battery throw lines SDA and SLC of I2C interface to input lines of MCIMX6X2AVN08AB microprocessor or the real time clock PCF2129T ensures an absence the back drive from the lithium battery to lines of an I2C interface?

[art · Accepted solution]

Anyway, since the real-time clock IC and the processor's I2C I/O pads are powered from differend supplies with potentially different voltages, the level shifting circuit must be used on the bus. This level shifting circuit will operate as the bus isolation circuit as well in case of powering down the processor and the rest of the system except of the real-time clock IC.

Have a great day,
Artur

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