AltIMU-10 v5 Sensor Schematic Help

Hi everyone,

I have been using sensor for some time and now i need to implement it to my pcb and i have a question.

The schematic has Q1 Q2 mosfets which are for level shifitng and my mcu is working with 3.3v logic so i will get rid of them. My question is should i also remove R3 R4 resistors since i think they belong to 3.3v side of level shifter circuit or should i leave them.

Thanks

Hello.

Pullup resistors like R3 and R4 are needed for I2C communication, so you should keep those in your design.

-Jon

Thank you Jon for reply.

The mcu’s sda scl lines are pulled up, still do i have to keep R3 and R4.

The strength of the pull-up resistors you need on the SCL and SDA lines depends on a few things like the capacitance of the I2C bus and the frequency you want to use, but a common recommended value is something like 4.7k to 10k. If you already have pull-ups for those lines on your board, you do not need R3 and R4 as well. However, if you are talking about relying on the microcontroller’s internal pull-ups, you should probably still include R3 and R4 because internal pull-ups are typically significantly weaker than 10k. (If you find out later that the external pull-ups aren’t necessary, you can just not populate them on your board.)

-Jon