User Guide

10
must be a special compound so that it effectively transfers heat
from the chip on the Pi to the metal of the heat sink.
Figure 2. The heat-out points on a Pi (left); and installing a heat sink on the CPU (right)
Connecting Power
The Raspberry Pi requires a power supply of 5 V that can provide
at least 700 mA of current. Before connecting the Pi and turning
it on, you should check the rating of the power supply carefully.
Many cellphone chargers will work with the Pi, but some supply
less current than the Pi needs. Using inadequate power supplies,
or even powering the Pi from the USB port of another computer,
is not recommended as the lack of current may make the Pi
unstable. You should certainly avoid doing this if you need to
connect any other devices to the Pi.
Power can be fed in to the Pi through the micro-USB socket or,
if you have a suitable connector, through the general purpose
input output (GPIO) pins. However, providing power through the
GPIO header pins bypasses the on-board protection circuitry
that is designed to prevent damage to the device. For this
reason, it should only be attempted by people who are
experienced in building electronic circuits.
It is worth noting that the Raspberry Pi does not have an on/off
switch. Some operating systems can power down the device or
put it into standby mode but when you want to turn it off, you
will often have to remove the power supply or switch it off at the
wall socket.