A charger is marked: input 220V 200mA, output 5V 1000mA. Input power 220*0.2=44W, output power 5*1=5W. Some people will ask: So where did the remaining 39W go? Even the conversion process loss is not so exaggerated, right? Let's look at the answers to the questions:

The input is AC220V, the output is DC5V, the AC power unit is VA, the DC power unit is W, the two are not equal, the AC power includes, active power/reactive power/apparent power. DC Power only includes active power.

1. The input current of 200mA refers to the maximum input current (generally marked as 200-300mA), not the input current during actual operation. It represents the input current at full load operation under the minimum input voltage (rounded off with a little margin). Ps: The working voltage range of the power supply is generally nominally 100-240V, and is actually designed according to 90-265V.

2. AC, 220V and 200mA all refer to the effective value, and because the ac input is a rectifier bridge, the current is non-linear, the direct multiplication of the voltage and current effective value is not equal to the active power (multiply by the power factor, for those without PFC) Low-power power supply, generally measured about 0.3 to 0.5), the most convenient way to measure the input power is to use a power meter.

3. The energy efficiency of mobile phone chargers is generally 70-80%, and the specific indicators are related to the output power. For details, please refer to the calculation formula of the EPA or CoC fifth edition standard.

Simple calculation:

5V1A power supply, the efficiency is greater than 73.623% according to the US level VI energy efficiency requirements, and the efficiency is greater than 73.773% according to the EU CoC fifth edition.

5V2A power supply, the efficiency according to the US level VI energy efficiency requirements is greater than 78.704%, and the efficiency according to the fifth edition of the EU CoC is greater than 79.004%.

Then, for 5V1A power supply: output power: 5V*1A=5W efficiency is calculated as 74% (from the above calculation), then the active power of AC input: 5W÷0.74=6.757W The power factor is taken as 0.4 according to experience, then When the AC input apparent power is 6.757W÷0.4=16.892VA at the minimum input voltage, the effective value of the input current is: 16.892VA/100V=168.92mA, take 20% margin to get 200mA. That is to say, the problem of the subject, the difference between the input and output power is so much, mainly because the input power is wrongly calculated (it should be calculated as 100V), and the conversion ratio of power factor * efficiency is omitted.

SaiYue Technology Co., Ltd. is a mobile phone accessory solution provider that integrates design, research and development, production, sales and service with mobile phone chargers as its core. SaiYue Technology supports two cooperation modes of ODM/OEM for electronic products such as chargers. The products are of good quality and complete models. It has developed into a long-term strategic partnership with some regional distributors and agents.