• State TI Thinks Resolved
  • Locked Locked
  • Replies 6 replies
  • Answers 4 answers
  • Subscribers 62 subscribers
  • Views 277 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

LP87332B-Q1: LP87332B-Q1

Shlomi Yehezkia
Mastermind 6150 points
Part Number: LP87332B-Q1
Other Parts Discussed in Thread: LP8733-Q1, LP873222-Q1

Hi Team,

I plan to use LP87332B-Q1:

Output voltages  :  LDO0 = 2.5v,  LDO1 = 3.3v

But problem  :  at startup the LDO0 turns-ON at 3.3v  =>  risk to the load chip

Questions  :

-       Is there similar part without this startup state?

-       Can this be solved on this part?

-       Can I use SDA/SCL control for separately enable specific outputs?

 

Thanks,

Shlomi

 

  • 0
    TI__Expert 4155 points
    Shlomi,

    There are a couple different options you have here. The first would be to use the LP87332B-Q1, but keep the enable pin low, until you are able to modify the LDO0 output voltage through I2C. The second option would be to use the LP8733-Q1, which is designed to be configured through I2C at startup. This device by default has all of the regulators disabled, and no sequencing, so there isn't any risk of the regulator outputting 3.3V when you don't want it to, even if the EN pin accidentally goes high. The LP8733-Q1 is the safer option; it would just take more I2C commands since you would have to set all of the device settings, not just the one voltage that you want to change.
  • 0 in reply to Nick Jakse49
    Mastermind 6150 points

    Hi Nick,

    Thank you for your reply.  A followup question -

    In case I feeding the controlling MCU through one of the LDO outputs of the PMIC (using the default 3.3V) - I will need this LDO to turn ON when EN-pin goes high but I will still want the second LDO to remain off upon EN (to be controlled by the MCU through the I2C after it boots).

    Are there other device versions with different default settings for the regulators?

    Specifically - only one turns ON upon EN-->high., or different default voltage settings.

    Thanks,

    Shlomi

    LP87332.docx

  • 0 in reply to Shlomi Yehezkia
    TI__Expert 4155 points
    Shlomi,

    Sorry for the delay in response, I was out for the holidays.

    The LP873222-Q1 has LDO0 set to 3.3V and enabled by the EN pin, while LDO1 is set to be enabled by I2C. However, this is the lower current version of this device, so the BUCKs are limited to 2A instead of 3A. If the lower current is ok then this would be a good option, and would actually be cheaper.

    This is the only option I see without having to do a custom OTP, which would require a business case review, and would have a longer lead time. If you would like to go forward with this option you should contact your local TI sales representative.
  • 0 in reply to Nick Jakse49
    TI__Expert 4155 points
    Shlomi,

    I would also like to note that with this version of the device BUCK0 and BUCK1 would also turn on with the enable pin at 3.36V and 1.54V respectively.
  • 0 in reply to Nick Jakse49
    Mastermind 6150 points

    Hi Nick,

    It can be relevant for me. 

    Just making sure - LP873222-Q1 can support 2A at both DC2DC outputs simultaneously, am I correct? (+ 2 x 300mA at both regulators) 

    Thanks and happy new-year,

    Shlomi

     

  • 0 in reply to Shlomi Yehezkia
    TI__Expert 4155 points
    Shlomi,

    You are correct. BUCK0 and BUCK1 can simultaneously output a constant 2A, while LDO0 and LDO1 can output a constant 300mA.