USB Battery Charger
A USB battery charger can be the perfect solution to charging your mobile phone, earbuds, and other portable devices. They provide convenient access to a wide variety of power sources and can charge most portable batteries in about 30 minutes and 2.5 hours, depending on the device’s power draw.
But charging a battery requires more than the five-volt power provided by the Universal Serial Bus (USB) specification. A new USB specification called BC1.1 recognizes battery charging and allows up to 1.5A from a dedicated charging port (DCP) or charging downstream port (CDP).
Product Description
The usb battery charger, as the name implies, is a small but mighty USB powered device capable of charging up to two smartphones or tablets at the same time. The product features a USB 3.0 hub that supplies a whopping 900mA (or more) of juice to your devices. This is a significant amount of power, and the resulting charge times are among the best in class. The product also includes a clever circuit that keeps the gizmo from leaking all the power, and it’s a cinch to remove from your laptop for charging on the go. It’s a well made design that will please any power user on the hunt for a new gadget to keep the kids happy and occupied. This little beast also comes with a comprehensive warranty and a money back guarantee. The company’s website includes a wealth of information about its products, as well as a plethora of product reviews and customer feedback. The product is a worthy addition to any technology buff’s collection and comes with an industry leading three year warranty.
Specifications
USB is a popular standard for connecting power to portable devices. Over the years, it has evolved to include not only serial communication but also battery charging and AC adapter connections. This has resulted in a wide variety of plugs and adapters being available for most portable consumer devices.
There are a few key aspects to designing a USB battery charger that must be considered to ensure safe and effective operation. First, the voltage drop between the USB bus supply and the charge circuit must be high enough to support optimal battery charging times. This is important because it will determine whether a battery can reach full charging capacity or not, as well as how long the battery will last after it has been charged.
Another important design consideration is the input voltage of the USB supply. Generally speaking, the lower the supply voltage, the slower the charging process will be, usb battery charger and the shorter the battery charge time. To optimize charge times, the input voltage must be 4.2V or higher.
To minimize this voltage drop, the charging circuit was designed to use an LM3525 transistor and diode with low-dropout properties. These components allow the circuit to deliver a steady current to the battery until it reaches its full-charge voltage.
The charging IC also performs other functions necessary to support battery charging, such as D+ and D- short detection and a CDP identification function. It also monitors the battery’s weak-battery voltage, which allows it to recognize the presence of a dead battery and reduce charge current accordingly.
Finally, the IC also provides charging logic that supports USB BC1.1 power sources such as wall warts and auto adapters. These port types do not enumerate, which means that they don’t require system software to manage their charging.
The IC is compliant with the USB Battery Charging Specification, Rev 1.1 (BC1.1), which allows power sources to supply up to 1.5A. This is a departure from the initial USB 2.0 specifications, which only allowed up to 500mA. The IC can also impose restrictions on charging while the device is suspended, as specified in USB 2.0. This feature, a key element in the BC1.1 standard, can help reduce wake-up time and improve battery life.
Bottom Line
A well-designed USB battery charger enables portable consumer devices to use the most power for the least cost. In some cases, it even maximizes usb battery charger battery life while lowering customer returns and warranty repairs.
As a universal serial bus, USB can be used to connect many different types of devices with the same connectors and cables. It is a great way to get power to devices and allow them to communicate with each other without the need for a separate battery charger. However, the power limitations of USB and the size and cost barriers that are often present in portable consumer device designs mean that battery charging needs to be carefully designed to optimize safety and user experience.
The original USB 1.0 and 2.0 specifications limit the current that can be drawn from a standard USB port to 500mA. This is sufficient to charge small single-cell Li-ion batteries quickly, but it is not enough for larger, multiple cell packs.
To address this problem, USB-IF published the USB Battery Charging Specification in 2007 and a later version in 2010. This specification raises the maximum unit load from 500mA to 900mA on USB 3.0. This increase is critical for delivering the highest available speed to power-hungry USB devices, but it also creates a new set of challenges for device makers who have to design charging solutions to meet these higher requirements.
One solution is to design a self-enumerating charger IC that is aware of which USB ports are connected to it and selects the appropriate power load current limits. This allows for the creation of dedicated USB power sources like wall warts that don’t require system software to enumerate and select USB ports.
