Multi port Charger circuit principle

December 26, 2022

Multiple Usb Charging Station / Usb Power Strip / Multi-Port Charger Usb

In addition to direct power supply USB devices, a more useful feature of USB is to charge the battery with USB power. Because many portable devices (such as MP3 playback machines, PDA) and PC exchange information, battery charging and data exchange at the same time will greatly enhance the installation convenience on a cable. Combining USB and battery power supply functions to expand the work scope of the "non -restricted" device (such as a mobile web camera connect to PC or non -connected PC work). In many cases, there is no need to carry inconvenient AC adapters.

USB power supply

All host USB devices (such as PC and laptop) can provide at least 500mA current or each USB socket provides 5 "unit loads". In USB's words, "a unit load" is 100mA. Self -supply USB jack can also provide 5 unit loads. The bus supply USB jack guarantees a unit load (100mA). According to the USB specification and Figure 1, at the peripheral end of the cable, the minimum effective voltage from the USB host or the power supply jack is 4.5V, and the minimum voltage from the USB bus power supply jack is 4.35V. These voltages are charged (generally needed 4.2V) when charging lithium ion batteries, and the rest is small.

All devices inserted into the USB port must not be more than 100mA. After communicating with the host, the device can determine whether it can occupy the entire 500mA.

The USB peripheral contains one of the two jacks. Both jacks are smaller than the sockets in PC and other USB hosts. "Seriesb" and smaller "Series Mini-B" jack are shown in Figure 2. From the pin 1 (+5V) and 4 (places) and the Series Mini-B pin 1 (+5V) and 5 (places) of Series MINI-B, get the power supply.

Once connected, all USB devices need the host to identify it. This is called "enumeration". During the identification process, the host determines the power supply of the USB device and whether it is powered by it. For the approved device, the load current can increase the load current from 100mA to 500mA.

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