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TRF7970A: External pull-down resistor requirement

Natalie
Prodigy 40 points
Part Number: TRF7970A

According to SLOA205A, there are pull-down resistors on IRQ, DATA_CLK, and I/O1-7 when TRF79xxA is in PDM (although this post says the DATA_CLK pulldown is not active for EN = 0 and EN2 = 1). However, for standard operation (EN = 1), does TI recommend pulldowns on IRQ, DATA_CLK, and I/O pins (used for SPI bus -- MOSI, MISO, and SS)? These will be driven by an FPGA, but its internal resistors are weak. 

As stated by this post, could you confirm whether ASK/OOK and MOD require pulldown resistors?

Finally, does SYS_CLK have or require any pulldown resistance?

  • 0
    TI__Mastermind 18265 points

    Hi Natalie,

    to select the interface you use, the pins IO_0 to IO_2 have to be set according to Table 6-10 in the datasheet. The pins used for the SPI communication do not require external resistors. IRQ and SYS_CLK are active driven signals and do not require pullups.

    The pins ASK/OOK and MOD should be connected to GND with 1k.

    Best Regards,

    Helfried