Power supply to ST25DV-I2C for GPO output and I2C communication.

[KT_25]

I would like to use ST25DV-I2C for I2C communication and GPO output.

The datasheet states that to use GPO output, an external pull-up is required for the 8-pin package, and an external power supply (VDCG) is required for the 12-pin package.

However, I do not want to have an external power supply on the board.

Is it possible to transmit power to the ST25DV-I2C via RF, and then supply power to the pull-up or VDCG from V_EH?

Also, can power be supplied from V_EH to VCC for I2C communication?

[JL. Lebon]

Hello, 

In order for the I2C interface to work, there must be a power present on the VCC pin. 
If you don't have an external VCC source, you can connect the V_EH output to the VCC input pin and enable the energy harvesting. In this case, you will be able to power the device from its VCC pin only when an RF field is present and the I2C interface will be functional.
Keep in mind that I2C is an open drain bus and requires also pull-up resistors in order to work. Those pull-up resistors can be connected to a different power source than the ST25DV VCC, as long as this power source is in the range 1.8/5.5V.

For the GPO output, if you are using 8-pin package, it requires an external pull-up resistor as this output is open drain. You can also connect this pull-up resistor to the V_EH or to any other external power supply source that is in the 1.8/5.5V range (it can be different than the St25DV VCC voltage).
It is the same thing if you are using the 12-pin package: you can connect VDCG to V_EH or any other external power source.

Best regards.