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TPS65986 : PP_HV is mandatory to provide 5V

Franck-D
Prodigy 165 points
Other Parts Discussed in Thread: TPS65982, TPS65982-EVM, TPS54335A

Hello

I would like to know if i can use the TPD65986 with only 2 PDO.

The first PDO is  5V/3A  connected to the  PP_5V0

and the second PDO with just only 15V/3A connected to the PP_HV. 

Precisly i would like to know if on the PP_HV it is mandatory to provide a variable DC-DC with 5V and 15V

Thanks

Babtoo

  • 0
    TI__Mastermind 30310 points
    Babtoo,

    According to the USB PD "Power Rules", you must be able to provide 9V if you want to provide 15V.

    To be spec compliant, you would need to deliver 5V through PP_5V0 and 9V/15V through PP_HV. In this case, you would need a Variable DC-DC converter controlled by 1 or 2 GPIOs of the TPS65986.

    If you want to provide 5V & 15V without testing for USB PD certification, this design can be completed without the "Variable DC-DC" circuit.
  • 0 in reply to Brian Berner
    Prodigy 165 points

    Brian

    Hum i going to discuss wih my MKT to see if we need to be compliant or not.

    i suppose "yes"

    Thank you 

    Babtoo

  • 0 in reply to Franck-D
    TI__Mastermind 30310 points

    Babtoo,

    If the answer from your MKTing team is "yes", you may be interested in reading an Application Report () I wrote as an introduction to this topic or one of the 3 e2e posts () I wrote on the topic that each discuss a separate circuit with a schematic attached.

    Another option would be to use the TPS65982 with 3 stable voltage rails from fixed-output DC-DC buck converters. 5V would be connected to PP_5V0, 9V to PP_HV, and 15V to PP_EXT.

    If 15 Volts is the DC input to your system, your Power Path circuit would be identical to the TPS65982-EVM except for re-calculating the value of R104 to deliver 9V to PP_HV (instead of 12 Volts). The equation for R104 would be different depending on the DC-DC buck converter you use, but the TPS65982-EVM uses the TPS54335A (upgraded to -A version after the EVM was released).

    If 20 Volts is the DC input to your system and you still want to use the TPS65982, you will need to add a copy of the circuit and re-calculate for another resistor value to deliver 15 Volts to PP_EXT. This process of adding DC-DC buck converters as needed increases the BOM count, which is why we started writing technical papers on the "Variable DC-DC" design in the first place.