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How Flash Drives Work

Ryan Stutzman - Saturday, May 18, 2013

Parts of a flash drive

You plug it in, grab an important file, and yank it out. It all seems so simple. But have you ever wondered what is going on inside your flash drive as your files are moving to and fro?

Perhaps you’re like most people: perfectly content to enjoy the usefulness of your flash drive without ever considering the mysterious flow of electrons between the myriad tiny components that make it up. And that’s okay. But sometimes, even for the blissfully ignorant, curiosity can be peeked when a device stops doing the thing it's supposed to do, like when a flash drive breaks or stops being recognized by your computer.

For the electronics lay person who wants a general idea of how flash drives work, the following info is for you.

Flash Drives vs. Hard Drives

NAND memory chips

A key difference between flash drives and other types of memory devices is the lack of moving parts. Flash drives are solid state, which means they store data on a piece of silicon with zillions of tiny transistors, as opposed to traditional hard drives which use magnetic spinning disks.

Each transistor on the silicon chip holds a single bit of binary digital information: either 1 or 0. In flash drives, the transistor is set to 1 by default. To change one of these transistors' states to 0, an electric charge resulting in a crazy little process called Fowler-Nordheim tunneling is required.

One cool thing about flash memory is that it doesn't require a power source to remember what is on it. In fact, if you bury your flash drive in your back yard and dig it up a thousand years from now, the data will still be on the memory chip just as you left it.

The Brain of a Flash Drive

Flash drive microcontroller

Basically, the data on a memory chip is nothing more than a bunch of tiny ones and zeros. Making sense of those ones and zeros-telling them where to go and keeping track of where they are-is accomplished by the flash drive’s microcontroller. A flash drive’s microcontroller is roughly analogous to a computer’s CPU, or a human’s brain, but somewhat simpler, in most cases.

There is a vast array of brands and varieties of microcontrollers used by flash drive manufacturers. Some are better than others in terms of speed and durability. Second only to broken connectors, bad microcontrollers are the leading cause of flash drive failure.

How Flash Drives Communicate with Computers

USB flash drive connectors

USB flash drives talk with computers by means of either a standard USB 2.0 or USB 3.0 interface. At present, flash drives using the USB 3.0 interface are backwards compatible with the USB 2.0 plug.

USB 2.0 interfaces have four connections: a +5VDC power source, one positive and one negative data line, and a ground. USB 3.0 connectors have four additional data lines and a drain, creating a 10X increase in theoretical transfer speed.

In addition to the essential parts mentioned above, flash drive circuit boards are covered in lots of little surface mounted components like resistors, capacitors, diodes, oscillators, LEDs, and other parts, the primary purpose of which is to divide and direct electricity to the right places.

I hope that helps unravel a little bit of the mystery behind the flash drive. Don’t forget to back up your flash drive and let us know if we can help you recover lost photos or other data.

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