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UCC28951-Q1: Configuration of ADEL pin.

John11513
Expert 5720 points
Part Number: UCC28951-Q1

Hi team,

A question about UCC28951-Q1 datasheet:

For adaptive delays, pins ADEL/ADELEF are configured as:

My question is about the equation for RA/RAHI calculating:

Where is the '5V' in equation from? the voltage of CS pin is 5V?

Thank you,

John

  • 0
    TI__Mastermind 25570 points
    Hi John
    The reason for the 5V is that the circuit being designed is the one in the slua560C application report where the adaptive delays are tied to the 5V VREF pin rather than the 2V (max) CS pin. Tying these pins to VREF of course defeats the adaptive function as noted at the top of Page 50 of the DS.

    The application schematic in Fig 48 shows the normal way to use ADEL and ADELEF, that is connected to CS.

    The EVM uses a fixed delay and tying ADEL and ADELEF to a fixed voltage allows you to achieve shorter delays than tying them to GND.

    The best approach is to use the schematic in Fig 48, initially set ADEL and ADELEF to zero and then iterate to the best solution for your particular application.

    Please let me know if this isn't clear

    Regards
    Colin