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TPS65132: When can TPS65132 starting communicate by I2C

Shaquille Chen
Intellectual 1770 points
Part Number: TPS65132

Dear team,

When can TPS65132 starting communicate by I2C?

My customer test result shown that only when Vin higher than UVLO and EN be pull high, TPS65132 can communicate with outside.

Is because this device need enable by this two factor?

Thanks 

Shaq.

  • 0
    TI__Expert 8010 points
    Hello Shaquille,

    The internal oscillator for the I2C interface will be activated if UVLO has been exceeded independently of the state of the EN pins. This means you do have access to the I2C communication if EN is set low.

    Best Regards.
    Ilona
  • 0 in reply to Ilona
    TI__Intellectual 1770 points
    Hi Ilona,

    Thanks for your reply.
    I just test this on TPS65132LEVM. Only when one of EN been pull high, the device output will change.
    Below is the sequence I tried:

    1. Power on -> write 0x00 = 0Ah -> EN pull high : Vpos output still 5.4V
    2. Power on -> write 0x00 = 0A h-> write 0xFF= 43h-> EN pull high : Vpos output still 5.4V
    3. Power on -> write 0x00 = 0A h-> write 0xFF= 42h-> EN pull high : Vpos output still 5.4V
    4. Power on -> EN pull high-> write 0x00 = 0Ah : Vpos output become 5V
    5. Power on -> EN pull high-> write 0x00 = 0Ah-> write 0xFF= 43h -> power off -> power on -> EN pull high : Vpos output become 5V

    The result shown that the register only can change when EN been pull high.
    For the sequence #5, is there any risk to set the default value different from original design?

    The default value of TPS65132W are +-5.4V but customer needed +-5.7V .

    Thanks
    Shaq.
  • 0 in reply to Shaquille Chen
    TI__Expert 8010 points
    Hello Shaquille,

    What I was trying to say is that you have access to the I2C interface when VI>UVLO, meaning you can read and write to the register.
    Of course the output stages can only react on the programming if they are enabled.
    If you want to change the default setting of the device you will need to write the required setting from DAC into EEPROM by setting WED=1. This is what you are doing in step #5.
    It is a normal requirement that customers do have other default output voltages which is covered by featuring an EEPROM in the device. I do not see any risk doing so.

    Best Regards.
    ilona