June 15, 2023
USB charging has become the de facto method of charging various portable devices that we use nowadays, especially smartphones, notebooks and tablets.
Interestingly, the original USB standard, introduced in the mid-1990s, had nothing to do with charging. It was only intended for data transfer between the peripheral and the host. As the technology became more widespread, USB-power delivery (USB-PD) protocols for battery charging were added to the specification in 2007.
An early example of mass adoption of USB charging was Apple’s iPod, which used a USB cable to charge the device in 2001. In 2007, the USB Implementers Forum (USB-IF) released the USB Battery specification Charging (BC) 1.0, which standardized how devices should charge and communicate simultaneously over USB. Over the years, USB Power Delivery (PD) specifications have become increasingly popular, enabling higher power output and faster charging speeds for compatible devices.
USB power levels increased from a fixed 5V, 500mA in the first version of the spec, to a maximum of 20V, 5A in the USB 3.0 spec. The most recent major change was in 2021 with the USB PD 3.1 specification, which took USB charging to a whole different level, allowing up to 48V, 5 (240W) over a cable and USB Type-C connector with full functionality. Now, multiple devices can be connected to a USB-C charger at the same time, with the ability for each device to draw relatively high levels of power.
Why do we need so much power from USB port? If you think about what is being connected, often at the same time, the answer becomes obvious pretty quickly. Our everyday devices range from notebooks, smartphones, tablets, external hard drives, game controllers and AR/VR headsets on the one hand, to a new market for USB-C charging in power tools and e-bikes on the other. .
As a leader in power electronics, Infineon offers a range of USB-PD controllers through its EZ-PD product family. The EZ-PD CCG3 is an example of a powered USB Type-C port source controller. Complies with all the latest USB PD power profiles. Thus, it can be used in a myriad of applications, including power adapters, power banks, Type-C dongles, Thunderbolt accessories, monitors, docks, and notebook computers. The device, based on a 32-bit ARM Cortex-M0 MCU, is a programmable solution and its dual 64kbyte flash memory can be used for fail-safe firmware updates at any time.
Adding a layer of complexity
Designing high-power USB ports can be more complicated than standard USB ports as some new considerations come into play, including heat dissipation, power delivery, compatibility, and regulatory compliance with all applicable standards.
Another device aimed squarely at the USB charging port is Infineon’s highly integrated EZ-PD CCG7DC dual-port USB Type-C PD solution with integrated buck-boost controllers. It complies with the latest USB Type-C and PD specifications and is intended for multi-port consumer charging applications. The programmable part is designed with a 32-bit Arm Cortex-M0 processor, 128 kbytes of flash memory, and various analog and digital peripherals such as ADC, PWM, and timers. Dynamic Load Sharing enables intelligent redistribution of power budget between ports based on load conditions.
Keep it fresh
As power increases through chargers, heat dissipation is an obvious issue. Heat flow management is essential to avoid damage to the device and the USB port itself. In terms of power delivery, it is also crucial to deliver the precise amount of power without exceeding the maximum current ratings provided by the USB-PD standard. Therefore, implementing gallium nitride (GaN) devices is a natural fit.
At a high level, the use of GaN devices in battery chargers offers higher efficiency, smaller size and faster switching frequencies. For example, Infineon’s CoolGaN Integrated Power Stage (IPS) combines the robustness of 600V GaN Hybrid Drain Integrated Gate Injection Transistor (HD-GIT) structure with integrated EiceDRIVER gate driver technology in a single QFN package .
USB has gone from a simple data transfer mechanism to an invaluable feature in portable electronics. The ability to simultaneously charge battery-powered peripherals and other end devices up to reasonably high power levels has become an expected feature on today’s host devices.
#Power #USBC #Embedded #Computing #Design