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TPS2121: Question about PR1 and CP2 setting.

Kazuya Nakai59
Guru 21545 points
Part Number: TPS2121

 Hello guys,

 One of my customers is considering using TPS2121 for their new products.

 They want TPS2121 to function as the follows.

 1. When IN2 voltage is valid only (IN1 is not valid), OUT voltage is IN2 any time.

 2. When both IN1 and IN2 voltage are valid, OUT voltage is IN1 any time.

 Q1. Is it possible to function as the above?

 Q2. What are PR1 and CP2 setting for the functin above?

       Are the correct settings PR1=H and CP2=L then?

 Your reply would be much appreciated.

 Best regards,

 Kazuya.

   

  • 0
    TI__Mastermind 32650 points

    Hi Kazuya,

    Please reference Table 9-3 on Page 18 on the datasheet to get a quick summary on the working modes of TPS2121.

    1. Yes this is possible. Whenever the input 1 voltage is over the set OV limit or under the internal set UV limit, the device will automatically select IN2 and pass it to the output. When both inputs are valid, it is possible to set a priority structure which selects IN1 over IN2.

    2. Your understanding is correct but please make sure this is the actual performance you are looking for. By setting PR1 high (over Vref) and CP2 low (0V), you will ALWAYS prioritize IN1 over IN2 whenever IN1 is valid. This means that IN1 will be prioritized from 2.6V to OV. It is also possible to set a resistor divider network and the user is able to define when IN1 gets prioritized (eg: over a specific voltage).