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TPS549B22: How to select Vboot setting is from internal NVM or external pin-strap

Jason Dai
Expert 3720 points
Part Number: TPS549B22

Hello E2E,

How to select Vboot (startup reference voltage) setting is from internal NVM or external pin-strap on tps549b22?

Sincerely,

Jason

  • 0
    TI__Genius 12735 points

    Hi Jason,

    Just to clarify, are you asking how to enable the device when the input or other voltage source reaches a specific level? If yes, TPS549B22 has an EN_UVLO pin that can be used as an enable signal. This pin will enable the device when its voltage is greater than the enable threshold (1.45V min, 1.6V typ, 1.75V max) and the VDD input is greater than the VDD_UVLO threshold (4.23V min, 4.25V typ, 4.34V max). You can connect the enable pin to the input and use a resistor divider to control the exact point when the device will enable by adjusting the divider. 

    Best regards,

    Layne J

  • 0
    TI__Mastermind 48160 points

     

    The TPS549B22 always boots to the voltage defined by the VSEL pin.  The voltages values listed in Table 3 on page 18 of the data sheet http://www.ti.com/lit/ds/symlink/tps548b22.pdf#page=18 for codes 0001 - 1110 are hard-coded voltages.  Codes 0000 (Short to AGND or 1.78k-Ohms) and 1111 (187k or Pull-up to BP) select voltage stored in NVM, which ships from the factory programmed to 0.975V.

  • 0 in reply to Peter James Miller
    TI__Expert 3720 points

    Peter,

    Do you mean that if user connects VSEL pin to either GND or 187k to ground, user could use NVM to set any boot up voltage, am I right? 

    Jason

  • 0 in reply to Jason Dai
    TI__Mastermind 48160 points

     

    If the user selects and of the 4 VSEL options that select a reference voltage of 0.975V (Open, Short, 187k or 1.78k) the USER can change the VBOOT voltage by setting VOUT_COMMAND and storing that value to NVM using STORE_DEFAULT_ALL.

    For ease of selection, I would recommend Either OPEN (Latch Off) or Short to AGND (Hiccup) depending on the user's preferred fault response selection.