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Using STM32F723 I2C with multiple slaves at different voltages

Rookie38
Associate III

Dear ST Microelectronics Team,

I want to connect a STM32F723IE with I2C as master, which is powered with 3.0V, to a bus with one slave with 3.0V and to another slave with 3.8V. From the datasheet I can see that the GPIOs are 5V compliant, but can the I2C peripherals still work correctly. While researching (I am still learning the electrotechnical conditions for the correct use of I2C) I come across the use of so-called bidirectional voltage level converters.

- Is the use of a level converter necessary?

- Where can I find out from the STM32 datasheets, which voltage range is tolerated by the I2C periphery?

Thanks a lot

1 ACCEPTED SOLUTION

Accepted Solutions
Uwe Bonnes
Principal II

See chapter 6.2 Absolute maximum ratings, 6.3 Operating conditions and Table 9/10 in chapter 4. Probably the 3.8 Volt slave is totally happy with a Vhigh of 3.0 Volt, so check if pull up to 3.0 v is sufficient. Even pull to 3.8 Volt shoyld work on FT pins. But power on the 3.8 Volt and no power on 3.0 Volt will be need to the absolute maximum Vdd-Vss of 4 Volt.

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2 REPLIES 2
Uwe Bonnes
Principal II

See chapter 6.2 Absolute maximum ratings, 6.3 Operating conditions and Table 9/10 in chapter 4. Probably the 3.8 Volt slave is totally happy with a Vhigh of 3.0 Volt, so check if pull up to 3.0 v is sufficient. Even pull to 3.8 Volt shoyld work on FT pins. But power on the 3.8 Volt and no power on 3.0 Volt will be need to the absolute maximum Vdd-Vss of 4 Volt.

CYANG.1
ST Employee

Hi

To be safety, I would advise you to add level shift parts to avoid current leakage for you application tools.