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DS90UB933-Q1: Is it required to pull up the I2C to the 933 VDDIO?

Ted Zhang
Intellectual 2280 points
Part Number: DS90UB933-Q1

HI Team,

In datasheet mentioned that I2C should be pull up through a resistor to the VDDIO, however my customer is pulling up to an external voltage rail which is same voltage level as the VDDIO, however the voltage rail will power up 30ms later than the VDDIO.

Their I2C commands begin 5s after power up.

Is it ok or any risk?

Thanks

  • 0
    TI__Expert 3390 points

    Hi Ted,

    There is a power-up sequencing diagram in the datasheet (Figure 28) where it shows the timing of VDDIO rail. Since the VDDIO rail should be tied to i2c, it would mean that you want i2c bus to be pulled up at the same time as VDDIO. 30ms would violate that condition and therefore it is not recommended. You may still be able to communicate but it is difficult to state what can happen because the device is not tested under the condition that your customer has set-up. I recommend tying it to VDDIO and avoid any future issues.

    Regards,
    Mandeep Singh