>> Which strategies are common when it comes to interfacing
>> 3.3V SD Cards to a 5V PIC? I need to interface both 5V
>> devices and an SD card over SPI. Are there any level shifters that
>> are meant for this purpose? The 16-bit M-chip seminar suggested
>> that there will be an application note on the subject. Has anyone
>> seen that app note yet?
>
> I haven't seen a Microchip app note, but the way a lot of people do it for
> just a few lines is with a mosfet for each line. Page 43 of this Philips
> document gives an example:
>
> http://www.semiconductors.philips.com/acrobat/literature/9398/39340011.pdf
>
> Cheerful regards,
>
> Bob

The mosfet approach is used mostly where you have a bidirectional data
line, but SPI lines are all unidirectional. While the mosfet approach will
definitely work, it has quite a few parts when compared with a single
level translator chip from Maxim or others. Maxim also has bidirectional
level translators that use the mosfet trick plus a speed up monostable
trick.

Harold
(the ideal design has zero parts)

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