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Strange schematic for X-NUCLEO-53L1A1, I2C level shifter

JWill.12
Associate II

Hi,

X-NUCLEO-53L1A1 expansion board uses an IC (ST2329AQTR) to shift the 3.3V I2C bus lines of the MCU to a 2.8V I2C bus for the proximity sensor VL53l1x.

Why are there these strange connections between the 3.3V and 2.8V bus as shown on the schematic of the X-NUCLEO-53L1A1 (see attached file) ?

0690X000006CHmMQAW.png 

Thanks,

Jeremie

1 ACCEPTED SOLUTION

Accepted Solutions
Miroslav BATEK
ST Employee

I think the schematic is not correct, the 3.3V and 2.8V buses cannot be connect together (shorted).

Most probably solder bridges are missing in the schematic.

View solution in original post

4 REPLIES 4
Miroslav BATEK
ST Employee

The nominal power supply voltage for VL53I1x is 2.8 V.

I'm aware of that. My question is about the i2c level shifter, from 3.3 to 2.8V. Why are the 2 bus connected? What's the point of the level shifter in that case?

Miroslav BATEK
ST Employee

I think the schematic is not correct, the 3.3V and 2.8V buses cannot be connect together (shorted).

Most probably solder bridges are missing in the schematic.

Ok, we agree on that.

Thanks