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DP83822IF: Why is the function of strap not described?

Rain Wang
Expert 1370 points
Part Number: DP83822IF

Hi TI

1. The customer selects the chip DP83822IFRHBR, and the manual mentions LED_1 is the strap PIN. Why does it not describe the function of the strap? Is there any description of the strap function?

2. Can you send an email to help check the design schematic of this chip??

  • 0 in reply to Rain Wang
    TI__Genius 17780 points

    Hi Rain,

    The LED_1 pin is considered a strap since the LED pins automatically configure polarity on power up or reset. It does not affect any setting other than it's own polarity. From section 8.5.2 of the datasheet:

    "LED pins are automatically configured for the proper polarity based on the bootstrap configuration at power up or hardware reset. If an LED pin is resistively pulled low, the corresponding output will be configured as an active high driver. Conversely, if a given bootstrap input is resistively pulled high, the corresponding output will be configured as an active low driver."

    You can leave LED_1 pin floating if it is unused, otherwise a pullup/pulldown and current limiting resistor is required.

    I have sent you an email.

    Thanks,

    David