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SN74AXC4T774: SPI Interface using SN74AXC4T774PWR

SHYAMKUMAR MURALEEDHARAN
Prodigy 250 points

Part Number: SN74AXC4T774
Other Parts Discussed in Thread: TXU0304

Dear TI team,

I am using SN74AXC4T774PWR for my SPI interface between MCU and my SoC.

Whether pullup resistors are required at the CS, CLK, MISO, MOSI signals? I refered the below image from the datasheet and there are no pull up resistors used here.

image.png

Regards
Shyam

  • 0
    Guru 323390 points

    You need pull-up or -down resistors on all lines that could be disabled by the driving device. In general, /CS is always driven. I do not know what your SPI master does with the CLK/SDO signals; if they are disabled while the SPI bus is inactive, you need PU/PD resistors on A1 and A2. The SPI slave's SDO output is typically disabled when /CS is high, so you would then need a resistor on B3.

    Note that the TXU0304 is simpler and cheaper. (It would also need resistors.)