Finding a power supply for the Raspberry Pi

Update 2012/06/13: My multimeter measures 5.11V across the two test points, so the HP TouchPad supply seems fine, and is not delivering too many volts.
Update 2013/01/21: I ordered two more Raspberry Pis, and then wanted to have an identical power supply for each. Because the HP TouchPad power supply is now impossible to find at a decent price, I ordered three 5V USB (1A) wall chargers, part TOL-11456 from SparkFun for $3.95 each. As the Rpi was booting, the voltage across the test points measured, on average, 4.99V for two of the units, with the third unit measuring, on average, 5.05V. So, they seem to be functional but not perfectly identical. However, the USB connection at the charger was very loose, and I tried a few different USB cables that make firm connections with lots of other power supplies and computers, so I’m confident that the problem is with the port on the charger.

My Raspberry Pi was shipped today by element14, but I started researching power supplies last week. A page on www.soronlin.org.uk titled Raspberry Pi Power Supplies indicates that any cell phone charger capable of providing 0.7A (or 700mA) of current should suffice, but the author recommends choosing a name-brand unit, and preferably one that provides 1A (1000mA). A post on www.raspberrypi.org titled “The Boreatton Scouts meet a Raspberry Pi” describes a setup using an “old BlackBerry 700mA charger”, which the Raspberry Pi was fine with until a few USB peripherals were added.

I tend to over-provision, so based on the recommendation to use a 2 amp adapter in this forum thread at www.raspberrypi.org titled “Adequate Power Supply Critical to Pi Stability”, I picked up an HP TouchPad Power Charger for $4.99 with free shipping from the HP Home & Home Office Store. (That’s an awesome price, by the way.)

HP TouchPad Power Charger

The HP TouchPad Power Charger

It’s reportedly the same charger that originally shipped with the TouchPad, and it’s a 2.0 amp charger, so it should charge just about anything with a USB port, short of a notebook PC. It comes with a one-year warranty from HP, too. A good number of the reviews on Amazon.com complain that the included USB cable is lousy, but I have a number of short, 24AWG USB cables with ferrite cores from monoprice.com laying around, so no worries there.

The specs

Specs taken from the side of the PSU:

Input: 100-240V~50-60Hz 0.4A
Output: 5.3V-2.0A

Specs taken from the page at HP:

Maximum Output Power: 10 W

My only concern is that the 5.3 Volts exceeds the 5.0 Volts that the Raspberry Pi is designed for, but I’m reasonably assured this won’t be a problem. I have a multimeter, so I’ll be testing the voltage across the test points.

Alternatives

There is a good list of verified peripherals, including a number of known-good power adapters, at the RPi VerifiedPeripherals page at elinux.org. The HP Touchpad supply is listed among the known-good adapters, but it’s referred to as a “5V 2A Charger for HP Touchpad”.

Of course, monoprice has some USB chargers, too, and I’d probably pick up a 2.1A, 4 Port USB Wall Charger as a second choice (assuming it’s not still on backorder).

One thought on “Finding a power supply for the Raspberry Pi”

  1. Matt

    Hi, have you had any issues with the touchpad charger? Just curious since I ordered the model b board today and have a touchpad charger. Thanks

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