Hardware USB Hardmod question about electric potential

[Juiss]

I've been doing some research on hardmodding and I understand most of it, but I've read that you need a voltage of 3.3V or you'll fry your NAND and considering USB ports output 5V I'm kind of lost on what to do next.
I plan to add a micro USB port to my N3DS that will be connected to a modded SD adapter that will be put into a USB card reader, so nothing too fancy but I don't really know how one would convert the voltage.

 

[LameNobody]

I've been doing some research on hardmodding and I understand most of it, but I've read that you need a voltage of 3.3V or you'll fry your NAND and considering USB ports output 5V I'm kind of lost on what to do next.
I plan to add a micro USB port to my N3DS that will be connected to a modded SD adapter that will be put into a USB card reader, so nothing too fancy but I don't really know how one would convert the voltage.

The SD adapter does not supply 5v...
A USB port supplies 5v... So if someone accidentally plugged an actual usb cable into a 3ds.. it would fry the nand

 

[Juiss]

The SD adapter does not supply 5v...
A USB port supplies 5v... So if someone accidentally plugged an actual usb cable into a 3ds.. it would fry the nand

That's exactly what I wanted to know, thanks!

 

[The Real Jdbye]

That's exactly what I wanted to know, thanks!

Just to elaborate a bit more, SD cards use 3.3V as well so SD card readers already have voltage regulators built into them for that. Actually feeding 5V to a SD card's I/O pins should not fry it as it's such small amounts of current (I've done this in the past with my Arduino) but even though that particular SD card didn't fry when supplied with 5V that doesn't mean that it can't happen with other SD cards or with the 3DS eMMC.

The issue with plugging a USB cable into the port meant for a modded SD adapter cable is more that it feeds 500mA of current to pins which are not designed for it (the CMD, CLK, DAT0 lines which are not designed to use more than a few mA of current at most)

 

[Juiss]

Just to elaborate a bit more, SD cards use 3.3V as well so SD card readers already have voltage regulators built into them for that. Actually feeding 5V to a SD card's I/O pins should not fry it as it's such small amounts of current (I've done this in the past with my Arduino) but even though that particular SD card didn't fry when supplied with 5V that doesn't mean that it can't happen with other SD cards or with the 3DS eMMC.

Yea, I don't really have much knowledge about SD cards (can't say I've used them before I got my 3DS), I had no idea they were designed for 3.3V use so I thought I might have had to fiddle with one of my USB ports.
Thanks, I learned something new today