With household appliances, audio-visual products, popular, widely used in office automation and networking continues to evolve, more and more products with a standby function, such as battery bike charging, remote control, digital display, time, touch and heat functions and so on, and ready to meet user requirements. These new products, new technologies greatly facilitate our lives, but also caused a lot of energy waste. For example, the standby power consumption in digital TV l ~ 5W or so, set-top box standby power consumption 20 ~ 40W or so, personal computer and the monitor is about 5 ~ 10W standby power consumption, mobile phone charger is about 0.5 ~ 1W standby power consumption. According to the International Economic Cooperation Organization, said a survey, national energy consumption due to standby and about 3% of the total energy consumption to 13%. Statistical data: about l2% Australia, South Korea 1l% or so, about 10% in Germany, the UK 8%, 7% in Japan, the United States about 5%, 5% in Finland. China's urban households, the average standby power consumption has accounted for 10% of total household energy consumption, equivalent to each family to use with a 15 ~ 30W of the "long light." Standby power consumption as an invisible blood-sucking insects, while at the wasted energy of formation of a huge environmental pressures.

International Energy Agency (IEA) in 2000, production and sales of electrical products to the global energy company launched the initiative "1 Watt Plan", now has been the European Union, the United States to respond positively to 2010, all exports to these areas of its standby power consumption of electrical products must be reduced to 1 watt, which will become all have entered and tried to enter the European market of electronic products manufacturers of new non-tariff barriers.

2. Investigation of electrical and electronic standby power consumption

 "Standby power" refers to a function of the Electric Bikes equipment on standby when not in use, do not disconnect the power consumption of power occurred. With standby power consumption of electrical equipment are air conditioning, computer and communication systems (including the host computer, display, computer audio, printers, scanners, chargers, routers, etc.), home video and audio systems (including TV, DVD, VCD, audio, amplifier, set-top boxes, satellite receivers, etc.). In order to avoid the trouble of frequent mating electrical plugs, or appliance used to save the state of the setting, many users are accustomed to using the power and just keep the remote control to open the closed convenience appliances, electrical appliances to make long-term standby. Standby function to facilitate for residential customers, but also caused a lot of energy waste.

According to the Shanghai Power Company organized a recent survey, the city's air-conditioning, home video and audio systems, computer and communication systems of these three major home appliances, standby power total about 7 billion kWh, if the average power 1 kWh, needs to consume 468 grams of coal, it will waste more than 30 million tons of coal. Standby power consumption 700 million kwh per year, a direct result of consumers spending $ 300 million waste of electricity [1].

According to European Commission statistics, in 2005, EU-25 have installed 3.7 billion standby / off mode of the product, they will cause 47 trillion watt-hours of standby / off electricity consumption, which is equivalent to € 6.4 billion in electricity bills. By 2010, in electronic and electrical products within the European Union each year standby / off electricity consumption will rise to 62 trillion watts. If the EU Member States to take appropriate measures to reduce standby power consumption, l999 to 2010 years between the time-saving 39 trillion watts.

3. Domestic and international standards for standby power consumption

Since 2000, the International Energy Agency raised the standby power consumption of electronic appliances "1-watt plan" since the standby power consumption of electronic appliances increasing attention. Standby energy consumption enterprises voluntary agreement, the U.S. "Energy Star" certification, mandatory government regulations have been introduced. China is a major exporter of electronic products, must be familiar with and understand these agreements and regulations, reduce standby energy consumption of the product across the standby power consumption of the technical barriers.

In 1992, the U.S. Environmental Protection Agency (EPA) and Department of Energy launched the "Energy Star" project, this program is not mandatory. Spontaneously with the vendor of this program, once its products to meet the "Energy Star" energy efficiency requirements, you can pass on their products labeled "Energy Star" logo. With the first products of this program is a computer and other appliances, then gradually extended to the motors, office equipment, lighting, appliances and so on. "Energy Star" program has become an international standard. Now, the world's 28,000 different types of terminal energy-consuming products have been Energy Star certified, annual sales of Energy Star products more than 1 billion. From November 2008, the "Energy Star" second edition started requiring standby power adapter or power must be less than 0.3W 0.5W, according to the adapter output power may be.

In December 2007 the U.S. issued the "2007 U.S. Energy Independence and Security Act" for the electrical and lighting products established the first mandatory federal energy efficiency standards. The content and the California Energy Commission (CEC) issued the "2007 California Energy Commission appliance efficiency regulations" requires the same. South Korea announced in 2010 the implementation of product standby power consumption is less than lW coercive measures, is the first country to implement mandatory measures. Australia announced to 20l2 years ago, all of its standby energy consumption of electrical and electronic products in the lW below. July 8, 2008, the European Commission released the first environmental design Directive No. 2005/32/EC implementing legislation motion, all designed to reduce electrical and electronic household and office equipment shutdown and standby power consumption [2].

In November 2008, the world's leading mobile phone supplier, Nokia, Samsung, LG, Motorola and Sony Ericsson, jointly announced the launch of a new, more stringent grading system standby mobile phone charger, any organization in today's world beyond the current or proposed in the standby power consumption specifications. According to Nokia's data, the phone in standby mode power consumption of its energy use accounted for 60% of the total. The new classification system will be zero to five stars logo to distinguish standby power consumption. For example, less than or equal to 30mW standby power consumption of mobile phone chargers are among the highest star in its five stars printed on the label. Conversely, if the standby power consumption ≤ 500mW, the charger will not label any star mark. We can do the following comparison: for the same output power charger, the new "Energy Star" EPS2.0 specification under the most stringent maximum no-load power consumption of 300mW, if carried out with the new star rating, then can only be assessed as two star. 4. Mechanism of switching power supply standby power consumption

Currently, most 100W following electronic devices such as power adapters, chargers, cordless phones, ADSL routers, LCD monitor and DVD, etc., are used off-line flyback switching circuit, the grid provides 85V ~ 275V AC converted to electronic devices need DC voltage. Normal operation, the flyback switching power losses include conduction losses and switching losses, and control circuit losses. Standby mode, the output current because the system is close to zero, conduction loss can be neglected, the switching loss and the loss of a main control circuit of the system standby power. Reduce the standby power consumption, should focus on the switching losses and reduce the loss of control circuit. Figure 1 shows the flyback switching power supply in standby mode the main type of loss, including the power tube switching losses, drive losses, transformer core loss, the output rectifier reverse recovery losses and switching losses are all losses buffers. All types of switching losses and switching frequency, reducing the switching frequency can reduce switching losses. Control circuit to initiate the loss mainly on the loss of resistance, and start directly with the loss of resistance rectified DC bus voltage and starting resistance. To ensure a wide input voltage operating conditions can reduce the starting current methods to reduce the startup resistor losses.

5. Low-power standby power solutions

As a leading manufacturer of power management IC, BCD Semiconductor Manufacturing Limited (BCDSemi) long-term commitment to efficient, low standby power consumption of green power solutions development and research.

As early as 2004 BCDSemi company pioneered an industry standard PWM controller with the 384x and is fully compatible with intermittent low-standby "green power" controller, AP384xG. AP384xG compared with the standard PWM controller 384x the most obvious difference lies in its internal addition of a controlled current source, current source charging through the comparison level to improve PinCS under light load conditions to achieve the intermittent mode to reduce standby power consumption . Meanwhile, AP384xG specially designed low starting current circuit, so that starting current of 200uA from the typical reduced to 40uA, greatly reducing wear and tear on the startup resistor.

As a special design considerations, AP384xG PWM controller with the 384x and is fully compatible with standard features, providing the so-called "Plug-and-Play" of "green power" solution. Users do not need to modify the original design of the case, replace the 384x with AP384xG while adjusting to a handful of resistors, capacitors parameters, you can greatly improve the power conversion efficiency (55% to 65%) and to reduce standby power consumption (3.25W ~ 0.5W), successfully passed the "Energy Star" energy efficiency certification [3]. Because of its significant energy savings and compatibility, AP384xG in the DVD power supply, CRT / LCD monitor power, electric bicycle charging power supply and so the field has been widely used, has so far sold more than 50 million pieces, save energy has accumulated in recent social 130 million kwh.

As the world's leading provider of mobile phone chargers, BCDSemi company in June 2009 launched a five-star meet the most stringent standards for low standby power charger solution, AP376x series, less than 30mW no-load consumption can manufacturers to easily meet the Energy Star EPSv2.0 including all of the world, including the charger / adapter, energy efficiency and load specifications.

AP3768 is BCDSemi company's second generation of the primary controller on behalf of the product, its design, in addition to the successful continuation of the first generation product architecture, eliminating the need for costly external components but low reliability, high precision output voltage / current control, to ensure production system under the conditions of ± 5% of the output voltage / current tolerance. AP3768 integrates a more accurate adjustable cable compensation function, which allows customers to adjust the value of an external resistor voltage to achieve any compensation to meet the different diameter, length of output cable applications. The patented "Sub-μAStartup" technology and low operating current is to achieve ultra-low standby power consumption of 30mW technical assurance.

Figure 2 shows a typical application of AP3768 and the main line curve.