• State Resolved
  • Locked Locked
  • Replies 1 reply
  • Subscribers 63 subscribers
  • Views 464 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TPS23754EVM - Overriding UVLO via PPD

Fernando Lopez
Expert 8230 points
Other Parts Discussed in Thread: TPS23754, TPS23754EVM-383, TPS23754EVM-420

Hello,

We are using the TPS23754EVM for evaluating a 24V over PoE application. The input UVLO is 30V, and I read in the datasheet that the TPS23754 has the PPD pin that allows to override the normal UVLO using a 24V external adapter.  From the EVM user guide I see that the jumpers involve in getting this functionality to work would be J6 and J7. 

The datasheet mentions that the 24V needs to be connected from VDD to VSS. What are the jumpers configurations for this? Is the 24V applied in J1(EVM user guide specifies 33-57V on J1), if not where? Do we need to remove/change any resistor on the EVM to get this to work?

Let me know if you need any more information. Thanks.

  • 0
    TI__Mastermind 42795 points

    Just to confirm, are you referring to TPS23754EVM-383? Because there is also TPS23754EVM-420 also. The TPS23754EVM-383 operating range is 33V-57V and as such is not suitable to use with the reduced UVLO application (TPS23754EVM-383 can only work with a 36V or 48V DC adapter).

    If you have TPS23754EVM-420, then you can test the reduced UVLO function as follows:

    1. Remove the shunt on J9 (not to use the APD function)
    2. Put a shunt on J10 between pins 2 and 3 (VSS position)
    3. Put a shunt on J4 between pins 2 and 3 (VDD position)
    4. Put a shunt on J8 (to use the PPD function.
    5. For a 24V adapter, we program the turn on for ~20V. Change R1 from 100k to ~46.4k.
    6. Now a 24V adapter can be connected to the J3 connector to power the DC/DC converter through the TPS23754 hotswap. Note that you cannot achieve the full 5V/5A at the output of the converter without exceeding the current limit of the internal hotswap.