TESEO LIV3F IO Supply Voltage

[ABouk.1]

Hello,

I would like to connect a TESEO LIV3F to an STM32 MCU that is powered using a 2.4v supply.

Im wondering if I can drive TESEO's Vcc_io with a 2.4v supply or if I should use a 3.3v according to the datasheet and put a level shifter between them both.

The first option is far the best for me ...

Thanks,

[RhSilicon]

In fact, in the recommendations there is a different power range for the VCC_IO.

Manufacturers usually inform the values of VIH, VIL and VOH, VOL so that the user can confirm whether it will be possible to meet the parameters, but I did not find this, really weird. For example a datasheet of SN74HC04:

 

 

 

[ABouk.1]

Thanks for your reply,

Since it's the same technology than the STM32, I assume that, for the TESEO LIV3F, the minimum voltage for HIGH level is 3.3 * 0.7 = 2.31V.

The STM32 that communicates with it outputs a voltage for HIGH lvl between 1.95v and 2.4v so It may not work sometimes.

I need to figure out if it's possible to connect it directly to 2.4v and operate the I/O pins correctly.

[RhSilicon]

Really having to use only the IO bus with a higher voltage is not very interesting, but it seems to be the recommended option. What are your power supplies?

[ABouk.1]

I have 3 power supplies : 2.4v, 3.3v and 5v

I can use the 3.3v for the vcc_io but I need to use a level shifter after that.

My goal is to avoid adding this level shifter, it brings extra cost, extra power consumption ...

[RhSilicon]

What type of data bus are you using? UART or I2C? It might be possible to implement the shift level using discrete components.

[RhSilicon]

Image sources: https://www.okdo.com/project/level-shifting/

AO3400 Gate Threshold Voltage: 1.45V and AO3401 Gate Threshold Voltage: 1.3V

[RhSilicon]

BSS138 VGS: 1.5V

https://learn.sparkfun.com/tutorials/bi-directional-logic-level-converter-hookup-guide/all