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TI Home » TI E2E Community » Support Forums » Power Management » PMU » PMU Forum » LP3972 I2C pulled up
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LP3972 I2C pulled up

LP3972 I2C pulled up

This question is not answered
Chee Wooi Cheok
Posted by Chee Wooi Cheok
on Aug 02 2012 04:18 AM
Prodigy80 points

On LP3972 application note (literature Number: SNVA235):

The two I2C lines are pulled-up to 3.3V in reference design board. 

On LP3972 data sheet (literature Number: SNVS468J):

It is stated in page 4/62 that the two I2C lines are pulled-up to 3.3V via IO source.

But on page 18/62 of data sheet, it is stated that the VIH of I2C lines are spec at VRTC max (which is 2.8V)

In this case, even the reference board design is violating the IC specification of VIH (max) = VRTC (2.8V).

Is there an update to the I2C maximum VIH voltage?
The maximum VIH voltage should be 3.3V or the reference design is just not designed according to spec?

Kindly enlighten

PMIC solutions
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  • Sheng Jin
    Posted by Sheng Jin
    on Aug 03 2012 18:32 PM
    Prodigy320 points

    Hi,

    since the eval board were designed and tested using 3.3V, then the max VIH voltage should be 3.3V, datasheet need to be updated according to refrence design...

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  • Chee Wooi Cheok
    Posted by Chee Wooi Cheok
    on Aug 05 2012 01:10 AM
    Prodigy80 points

    Hi Sheng Jin. Thanks for your fast reponse.

    I think it depends on which power domain the I2C signals are tied to. If they're tied to Vin, then the VIH voltage should be VIN instead of VRTC. What do you think?

    Will I be informed when data sheet is updated?

    Thanks & regards

       

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  • Sheng Jin
    Posted by Sheng Jin
    on Aug 07 2012 12:26 PM
    Prodigy320 points

    Yes, I think so. I will contact the right person to update the ds later..

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  • Chee Wooi Cheok
    Posted by Chee Wooi Cheok
    on Aug 07 2012 22:18 PM
    Prodigy80 points

    Noted with thanks.

    Regards

     

    PMIC solutions
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