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SN65LVDS93A: No internal Pull up/down ?

user5163865
Genius 3980 points
Part Number: SN65LVDS93A

Hi,

The SYSBOOT 0 to 18 terminals of the CPU (AM437x) are connected to the D0 to 15, D24, D25, and D26 terminals.

In order to maintain the desired level during power-up, the SYSBOOT pin is connected with a 10k ohm pull-up or pull-down resistor.

Q.
Does D0-D26 of this device have an internal pull-up / down during SHTDN=Low?
Customers are concerned that the internal pull-up will prevent the BOOT sequence from being selected correctly.


Best regards,
Hiroshi

  • 0
    Guru 316690 points

    All these inputs have integrated pull-downs; see Rpdn in section 7.5 of the datasheet.

    Section 9.4.2 does not mentions the inputs, so the pull-downs appear to be active even when /SHTDN is low.

  • 0 in reply to Clemens Ladisch
    Genius 3980 points

    Thank you for your answer.
    Do you know the minimum pull-down resistance value?

    Customers consider it the information they need to determine pull-up resistance.
    Now they are using a 10kΩ pullup.
    However, the recommended circuit in the data sheet is 4.7 kΩ.
    Should we change it to 4.7k considering the variation in resistance value?

    This is just a weak pull-down, so I think this question is too cautious, but please let me know if you know the minimum resistance.

    Best regards,
    Hiroshi

  • +1 in reply to user5163865
    Guru 316690 points

    What supply voltage are you using? Anyway, 10 kΩ appears to be enough to reach VIH.