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TPS2116: Power subsystem validation

Michal Slomiany
Prodigy 10 points
Part Number: TPS2116
Other Parts Discussed in Thread: TPS2216,

Hi,

I'm designing a research platform and want to ensure that the parts I'm using meet project requirements.

Power MUX requirements:

  1. During normal operations (research flights) board will be powered by the battery pack. On the schematic, it's the VBAT group. 5.0V LDO stabilizes battery voltage.
  2. The board will be powered by a USB outlet during debugging and lab research. On the schematic, it's the VUSB group.
  3. The board should work both when only USB is connected and when only the battery is connected.
  4. The board should work when both sources are present. In this case, USB should take priority. 

I've chosen such resistors in the divider that 5V on VBUS gives 1.25V on the PR1 pin. Is it enough margin to avoid accidental switching? I want TPS2216 to tolerate 4.5V on the VUSB bus.

I think TPS2116 meets all requirements, but I will be grateful for confirmation. 
I also want to ensure that the STAT pin and connected LED will work as intended. 

My second issue is the TPS78433 EN pin. The datasheet suggests connecting it to an MCU pin. However, I don't have available pins on the MCU. Is it correct to connect it to the VIN via the resistor and perform a shutdown by pulling it to the GND via TACT switch? I want this feature available as it's a prototype series, and I want quick access to reset LDO to perform a power-on sensors reset.

The Schematic is attached in PDF.

Thanks,

Michał

Power_subsystem.pdf

  • +1
    TI__Genius 13300 points

    Hello Michal,

    Yes you have this setup correctly and will work as you've described for both TPS2116 and the LED setup.

    When ST goes high the Vgs of the external FET will be at ~5V causing the LED to turn on. When ST is pulled low so is the gate of the FET turning off the LED.

    Regards,

    Kalin Burnside