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Original question:

BQ76952EVM: BQ76952EVM

BQ76952EVM: I2C and REG1 activation

Vadim Lebedev
Prodigy 160 points
Part Number: BQ76952EVM

Tool/software:

Hello,

I'm using BQ76952EVM,  and interfacing to it using EXTI2C connector on J17.
When i have USB cable attached to the board - I2C works fine 
But when i deconnect the USB port - I2C does not work or initialiy works but fail later. 


I'v tried to to activate REG1.

The activation is done in two phases:
 1. i enter UPDATE mode, write 0C into REG12 Config  register to configure REG1 to 3.3 V, and exit UPDATE MODE
 2. Enter UPDATE mode, write 0D into REG12 Config  to enable REG1 and exit UPDATE Mode.

I've tried to measure with and without USB cable bteween my PC and the EVM -  same result: No 3.3 V  to REG1 pin.


When i measure voltage on between REG1 pin on J2  and VSS   i  do not see 3.3  but something around 4 mv.

Any advice?

  • 0
    TI__Expert 3425 points

    Hi Vadim,

    We have received your request and will work to answer it as soon as possible. 

    Our normal support team is OOO and will be returning 12/10 to help with your inquiry. 

    We appreciate your patience and understanding.

    Best, 

    -Luis Torres (PME

  • 0 in reply to Luis Torres
    TI__Genius 17755 points

    Hello Vadim,

    Thank you for your patience. 

    Have you enabled REG0 (internal voltage preregulator) by chance? REG1 and REG2 LDOs take their input from the REGIN pin. The REGIN pin voltage can be supplied externally or internally (through REG0). The preregulator is enabled through Settings:Configuration:REG0 Config.

    More information regarding this can be found in Section 6.3.1 Preregulator Control and Section 6.3.2 REG1 and REG2 LDO Controls of the BQ76952 Technical Reference Manual.

    Best Regards,
    Alexis

  • 0 in reply to Alexis_H
    Prodigy 160 points

    Hi Alexis,

    Thank you for your response.
    This solved the problem of missing REG1 voltage.

    However the problem of unstable I2C persist...
    Any advice?

  • 0 in reply to Vadim Lebedev
    TI__Genius 17755 points

    Hello Vadim,

    I'm glad we solved the issue of the REG1 voltage.

    Can you please provide an image of your setup? A logic analyzer file of the communication may also be useful to see what’s happening.

    Best Regards,
    Alexis