Question about SD card reader

[TecHNooB]

How come the output from the SD card reader is only 3.3V? Is there a reason for this? And is there an easy way for me to bump it up to 5V (with Vcc at 5V)? I need to send data from the card reader to the SPI which uses TTL voltage levels.

 

[PottedMeat]

"SD Card Reader" - are you talking about a Secure Digital/Multimedia Card socket, or some sort of custom device?

...it's a standard, well at least I think SDMMC specifications say they're ~3.3-3.6V maximum.

Use an open drain hex buffer like a http://www.fairchildsemi.com/pf/74/74LCX07.html .

Buffer each signal.

Power the chip with 3.3V
Hook the SPI MOSI pull up resistor to 3.3V
Hook the SPI MISO pull up resistor to 5V
Hook the SPI CLK pull up resistor to 3.3V
Hook the SPI CS pull up resistor to 3.3V

 

[bobsmith1492]

Most 5V inputs are compatible with 3.3V outputs and some 3.3V inputs are 5V-tolerant... check yer micro. Otherwise there are lots of level conversion ICs out there (see the above).

EDIT: Also, most micros use 3.3V or less anyway... perhaps try a different micro?