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unused MMCSD0 pins, float or pull up?

Mohammad Ali Koteich
Intellectual 365 points
Other Parts Discussed in Thread: OMAP-L138

Hi,

If I'm using a 4-bit mode configuration, ports MMCSD0_D4-7 are unused. Should these just be left floating? or should they be pulled up?

Also, the shcematic checklist recommends 51K pullups on the MMCSD lines, but nothing of that nature is mentioned in neither the datasheet or the technical reference manual. Can the pull-ups be omitted? (I need all the space I can have)

Regards

Koteich

  • 0
    TI__Guru 64500 points

    Mohammad Ali Koteich said:

    If I'm using a 4-bit mode configuration, ports MMCSD0_D4-7 are unused. Should these just be left floating? or should they be pulled up?

    You can leave these pins floating provided that you do not route any traces from the balls of the associated signals.  There are internal pulls on these pins which can be enabled and configured as a pull up or pull down as described in some detail in the OMAP-L138 datasheet in Table 2-23.

    However, if you route these signals to test points, then the internal pulls are not strong enough to address any noise that may be picked up by these traces.  At that point, you should have an external pull resistor.