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LP87702-Q1: Recommended Termination of Unused Output

Mitchell
Expert 4915 points
Part Number: LP87702-Q1

Hi Team,

My customer is only using two rails on the LP87702-Q1 and plans to disable the boost via I2C at startup.

What is the recommended termination of VOUT_BST and SW_BST? Is it OK to leave them floating?

Thanks,
Mitchell

  • 0
    TI__Genius 17380 points
    Hi Mitchell,

    Generally we recommend placing components for rails that power on by default, even if they will be disabled after start-up, but I don't know for this specific device. I've assigned it to our dev expert in EU time zone, so you should have a response back in the morning.
  • 0
    TI__Intellectual 950 points
    Hi Mitchell,

    If you are using LP87702DRHBRQ1 device, recommendation is to connect all recommended parts. From the BOOST point of view parts are BST_SW input capacitor 10uF/10V, BST_SW input inductor 1uH and BOOST output capacitor 22uF/10V. If the recommended parts are not placed and some special case device boot, it will boot by default OTP settings where BOOST is enabled. Following scenarios will reset the device:

    7.3.9 Device Reset Scenarios
    There are four reset methods implemented on the LP87702-Q1:
    • Software reset with SW_RESET bit in RESET register
    • NRST input signal low
    • Undervoltage lockout (UVLO) reset from VANA supply
    • Watchdog expiration (depending on watchdog settings)

    With custom OTP BOOST can be disable by default.

    With Regards

    Tuomo