■ FIGURE 3. Here is the flowchart of the
application. Most of the time, the Green
Standby is in a deep sleep mode, helping
to consume only around 50 m W when idle.
recognizes normal operation, the relay
remains activated. If the current drops
below a preset threshold level, the
relay is deactivated after a few seconds
and the mains outlet is powered
down. See Figure 2 for a detailed
Good for the
Standby mode of operation refers
to the lowest power consumption
mode which cannot be switched off
by the user and that may persist for an
indefinite time when an appliance is
connected to the main electricity
supply and used in accordance with
the manufacturer’s instructions.
Standby power is a relatively new
phenomenon. An ever-growing number
of consumer goods and appliances are
now designed in a way that they draw
power 24 hours a day, seven days a
week, every week of the year.
Standby is often necessary to
power certain core functions or to
sense communication for those
products that are waiting to provide
full services. This power is consumed
not while the appliance is being fully
utilized, but while it awaits instruction.
However, in many cases, standby power
serves no useful function or operates at
Some studies estimate that the
amount of energy wasted by running
dormant devices left plugged in on
standby power could light up, heat, and cool the homes of
two-thirds of the planet. In the latest big study to track
household energy use, the Australian government last
year found that households squander 10 percent of their
electrical bill on electronics that invisibly suck power.
As an example, other studies appraise that the annual
collective standby power draw from households in the
USA is around 8 Gigawatts — equivalent to the electricity
production of eight large power plants. Globally, standby
power consumption is estimated to be responsible for
about 1% of the world’s carbon dioxide emissions.
Relay & LED
Wake up event: RTC interrupt every half a second
Wake up event: Infrared Remote Control Key Pressed
Relay & LED
■ FIGURE 4. Close-up view of the Green Standby’s internal
circuitry. The hardware is so simple because the number of
active components has been reduced in order to lower the
total system power consumption.
October 2009 41