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TPS65381A-Q1: Output resistance of DIAG_OUT

Jinqi Zhu
Prodigy 40 points
Part Number: TPS65381A-Q1
Other Parts Discussed in Thread: TPS65381EVM

In the data sheet of tps65381a-q1, page 35, Note:

"In the application, a series resistance of at least 100 kΩ is required on the input capacitor

filter of the ADC input of the MCU. "

what  is the reason that a 100k resisor should be put here?

In other document, TPS65381EVM User's Guide , SLVU847A , page 4, in this schematic , only a 100Ω resistor is add here.


100k or 100, which one is correct?

  • 0
    TI__Genius 9380 points

    Actually both are correct. When you read a little bit more you will discover that DIAG_OUT can feed both a digital I/O and an ADC.

    When DIAG_OUT is used for digital I/O a 100 Ohm series resistor is recommended to prevent a possible short from damaging the DIAG_OUT buffer.

    When DIAG_OUT is used with an ADC a 100K Ohm series resistor along with a capacitor will create a very clean analog signal for the ADC.

    I hope this answers your question.