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TPS7B69-Q1: some questions

Jiawei Hu1
Expert 5385 points
Part Number: TPS7B69-Q1

Tool/software:

Hi team,

From datasheet, the min value of input is 3.65V when ramp Vin up until the output turns on, but from BYD test, we can see there will be output when VIN ramp up to 1.6V, could you kindly check this at EVM? Thanks!

Ramp VI up until the output turns on

  • 0
    TI__Expert 5385 points

    Hi team,

    Pls help reply this question, thanks!

    What is the meaning of 3.65V? From the datasheet, seems we can make sure there is no output when we ramp up Vi, which is contradicts below another statement, also from datasheet.

    BR

    Jiawei

  • 0 in reply to Jiawei Hu1
    TI__Intellectual 790 points

    Hello there,

    I just had a couple questions regarding your concern. 

    1) It shows that you start at 1V and then ramp up 1.65V for there to be an output. Why are you starting the input at 1V?

    I ask since I think that allowing the device to "soft start" at 1V could be a reason for the difference in ramp values.

    Typically we tend to start out our test at 0V and consistently ramp up the input voltage.

    2) Why are ramping up the input after some time has passed at 1V?

    Regards,

    Jorge

  • 0 in reply to Jorge Del Rio
    TI__Expert 5385 points

    Hi Jorge,

    Thanks for your reply.

    Jorge Del Rio said:
    Typically we tend to start out our test at 0V and consistently ramp up the input voltage.

    Pls see attached figure, BYD also did the test from 0V and found that there will be output when input reach to 1.6V, not 3.65V. Could you kindly feedback by today? BYD are pushing us, thanks!

    • Pls help test EVM and check what is the min input voltage when you get output.
    • Pls check what is the specify test condition of 3.65V? Ramping up from 0V? What is the Vi ramping speed?
    • Per datasheet, we don't have specific min UVLO, only have maximum UVLO 3V, is that right?

    BR

    Jiawei

  • 0 in reply to Jiawei Hu1
    TI__Expert 5385 points

    Hello Jorge.

    Could you kindly help feedback? BYD IS PUSHING US. Thanks.

    BR

    Jiawei

  • 0 in reply to Jiawei Hu1
    TI__Intellectual 790 points

    Hello there,

    So per the datasheet, the measurement listed there is a guarantee of the device working. For instance, the 3.65V measurement is saying that once the input reaches 3.65V, the device will remain on and function as intended. The 3V measurement refers to when the device is already on and you decide to power it off, it will remain on up until 3V. 

    The ripple at 1.65V is simply the LDO powering up but won't output the desired output until V_IN is 3.65V. 

    Regards,

    Jorge