PCA9306 without low reference voltage in the board

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PCA9306 without low reference voltage in the board

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hcontigiani
Contributor II

Hi,

 First of all thanks for your support. I have two differents boards connected by I2C, a single board computer (SBC) connected to a driver led in another board. The SBC board has a 3.3V I2C and the driver led a 5V I2C, so I am planning to use the PCA9306.
  The problem is that the SBC is already design and I cant take 3.3V from there. The connector only have I2C_SCK, I2C_SDA and GND lines to connect with the driver led board. My only chance is to include the PCA9306 in the driver led board but I dont have 3.3V reference for VREF1. The SBC already has pull-up 4.7K inside the board.
  I understand that VREF1 is only a voltage reference that may be closer to the voltage supply of the SBC, so I think that I could connect VREF1 to 5V via a voltage divider to reach the 3.3V (LDO is too expensive for this purpose)
  Based on your experience, could you be so kind to take a look to the following schematic? Is there any issue to use VREF1 based on VREF2?
PCA9306.jpg
Thanks a lot, Hernan
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hcontigiani
Contributor II

Only for record, I have tested this circuit on my final board and it works perfectly.

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