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PGA309: I2C Pull-up Resistors

Clayton Kleppinger
Prodigy 60 points
Part Number: PGA309

Hi,

I am starting a new design with the PGA309 bridge conditioning IC, and I am looking into using a 3.3V I2C EEPROM.  Most of the documentation does not indicate that pull up resistors are required for the PGA309 and that you can direct connect the I2C data lines.  Does the PGA309 have internal pull-up resistors to V+?  Or can I use different voltage level EEPROMS with this device?

Thanks,
Clay

  • 0
    TI__Genius 12100 points
    Hi Clayton,
    The PGA309 has internal current source pullups which source around 100 uA on the I2C bus lines. One issue with using an EEPROM with a different voltage level would be ensuring that the PGA309 actually registers a logic high. If, for example, you use a 3.3V EEPROM with a PGA309 running at 5V, the PGA309 will only register a high at ~3.5V (0.7 * 5), and communication will not work. If your application can tolerate a reduced output range, however, you could simply run the PGA309 from the same 3.3V supply as the EEPROM.
  • 0 in reply to Alex Davis
    Prodigy 60 points

    Hi Alexander,

    Thanks for the response.  I later noticed the voltage input levels mentioned on the datasheet and realized that I'll have an issue there.  Unfortunately, I believe right now that my application will require a 5V supply, but I will start hunting around for an appropriate 5V I2C EEPROM or look into a level translator.

    Thanks,

    Clay