The consumer electronics industry suffers from a gigantic electronic waste problem. The latest Global E-waste Monitor report suggests that some 1 million tons of power adapters are produced every year. These chargers are shipped with portable consumer devices such as laptop PCs, tablets, mobile phones, cameras, smart speakers, power tools and many other product types.
Functionally, these adapters are remarkably similar. They are capable of operating across a mains input-voltage range of 85 V to 264 Vac for use anywhere in the world. In addition, for most devices their rated power output is less than 100 W. Yet it is rare for manufacturers today to make it possible to use one device’s adapter to power a different product. In fact, the industry has succeeded in creating an astonishing array of cosmetically similar but functionally incompatible versions of the basic barrel power connector (see Figure 1).
Figure 1: A wide array of barrel connectors is in use in power adapters and battery chargers. (Source: Cypress)
This creates confusion for the consumer, who finds it difficult to distinguish one type of barrel connector from another. When a device’s power adapter is lost or becomes damaged, the purchase of a replacement requires a meticulous check that the replacement part is compatible with the device for which it is needed. And every time the user needs or wants to replace an electronic device, the charger will be disposed of, adding to the world’s accumulation of electronic waste.
Ideally, consumers would be able to use the same power adapter and connector across multiple devices. Such a universal connector would improve the user experience as well as save manufacturers the costs they currently incur to produce and ship adapters with every product they make.
There is no need for a new industry consortium to work out a co-ordinated response since such a connector already exists, is easy to implement, and is readily available: the USB Type-C connector. This interface is supported by the latest USB Power Delivery (PD) protocol, an industry standard for providing a maximum 100 W (up to 20 V at up to 5 A) to a power-consuming device.
Consumer-friendly features of USB Type-C
USB – the Universal Serial Bus – is an interface technology which provides protocols for data communication and power delivery. The USB standard-setting organization – the USB Implementers Forum (USB-IF) – outlines rigorous testing specifications used to validate the conformance of USB devices to the standard. It also strictly enforces interoperability requirements for devices labelled as USB-certified.
The result is that, through experience, consumers understand that the presence of a USB logo on a connector or cable indicates that it is compatible with any other unit carrying a USB logo. Furthermore, the USB Type-C connector and cable itself could not be more consumer-friendly as it is reversible and directionally agnostic.
For consumers, no new learning or habits need to be acquired before adopting the USB Type-C charger as the universal power supply for battery-powered devices. This includes laptop computers and smartphones as well as devices that send and receive no data, such as smart speakers, shavers and power tools, etc. USB Type-C chargers are already easily procured today: more than 500 third-party USB Type-C adapters, chargers, and power banks from multiple manufacturers are readily available to buy online or in stores worldwide.
By using USB Type-C as the universal power connector instead of a proprietary barrel connector, a device manufacturer reduces its contribution to the e-waste problem. OEMs can also choose to save the production and shipping costs incurred when bundling a power adaptor with its product. Manufacturers of Bluetooth headsets, action cameras, and other similar devices have already taken the step of not shipping a charger by default with their new products.
Today, hundreds of models of laptop computers and mobile phones from brands such as HP, Dell Apple, Lenovo, Acer, Asus, Huawei and Samsung feature a USB Type-C power-supply interface and charger. The penetration of USB Type-C power supplies in laptop computers and mobile phones will reach 100% in the near future.
The quickest way to implement a new USB Type-C power sink design
The USB technology underpinning a universal battery charger is ready for deployment today. The USB standard achieves interoperability through communication between the ‘host’ – such as a charger – and the ‘powered device’.
Communication under the USB-PD protocol enables a powered device to:
- detect a charger when connected via a USB Type-C cable
- discover the power profiles – which specify parameters including maximum voltage and current supplied to the powered device – that the charger supports
- specify the profile that the device requires from the charger’s supported power profiles
Because USB technology incorporates data communications as well as a power delivery protocol, product marketers and developers might be concerned that the design implementation is more difficult, complex, and lengthy than a barrel connector’s simple, non-configurable, non-signalling power-supply circuit. In fact, a proof-of-concept design for a USB PD 3.0 power input system via a USB Type-C receptacle can be completed in a matter of minutes. Implementing a production design is also remarkably simple, requiring few components and no firmware development.
The quickest route to a proof-of-concept design for a USB Type-C power input is to use a development kit which has a built-in USB PD 3.0 controller, transceiver and protocol firmware. For example, the Cypress Semiconductor CY4533 EZ-PD Barrel Connector Replacement (BCR) Kit based on the EZ-PD CYPD3177 BCR chip is a small, credit card-sized board which includes a USB Type-C receptacle, the EZ-PD BCR chip, a small number of simple components required for configuring the input current and voltage. The kit enables a product developer to quickly prototype a USB Type-C power input to their design, replacing the barrel connector.
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Figure 2: Creating a universal USB Type-C power input to a smart speaker using the EZ-PD BCR Kit from Cypress Semiconductor. (Source: Cypress)
Figure 2 shows how the kit might be used to design a prototype for a USB Type-C power input to replace the existing barrel connector power input to a smart speaker. First, the developer starts by selecting any USB Type-C charger that supports the required power profile. The USB PD 3.0 standard specifies output voltage options of 5 V, 9 V, 12 V, 15 V, and 20 V and output current of up to 5 A. A smart speaker requires an input of 15 V at 2 A.
Second, supply the speaker with the correct power input by selecting a pre-configured power profile. With a development kit, this is done by turning a rotary switch. Finally, fix the leads from the speaker’s barrel connector to the kit’s terminal block, plug the barrel connector into the speaker, and switch it on to test for proper operation.
In this prototype system, the USB controller performs all the USB power delivery functions. This includes managing communication between the power sink and the charger as well as turning the load switch on and off to initiate/stop the supply to the power sink. The controller also protects the power sink against damage caused by short circuit, over-voltage, or under-voltage conditions and provides system-level ESD protection up to 15 kV. As USB controllers come complete with USB PD 3.0 protocol firmware, there is no software development requirement to make the barrel connector replacement.
Once testing of the prototype has verified the proper operation of the USB Type-C barrel connector replacement, developers must convert the prototype to a production design. As today’s USB controllers are highly integrated devices, this is a relatively straightforward process. Figure 3 shows a complete circuit for USB Type-C power delivery that requires fewer than ten external components.
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Figure 3: A typical application circuit for a USB Type-C barrel connector replacement based on the CYPD3177 power delivery controller. (Source: Cypress)
These components are:
- The USB Type-C receptacle. As this is a standard part, the receptacle’s cost is low. It will continue to fall in price thanks to the economies of scale created by the adoption of the USB Type-C interface in high-volume products such as laptop computers and mobile phones.
- The USB controller, which connects to the device’s host controller (if desired, but not required) via I2C interface.
- Resistor divider networks to select the desired output voltage and current values.
Values for the resistors are provided in tables in the USB controller’s datasheet. Because of the small dimensions of the USB Type-C receptacle – just 2.4mm high – the space occupied by the complete power circuit is comparable to that of the barrel connector power supply that it replaces.
Green and convenient
The environmental, commercial, and consumer benefits of replacing the plethora of barrel connector types with a universal charger for <100 W battery-powered devices are huge:
- Reduced e-waste
- Reduced use of the materials for manufacturing single-use chargers
- Reduced numbers of charger stock-keeping units for OEMs which ship a different charger with each product
- A single charger for all the devices a consumer owns
- Easy replacement of faulty or misplaced chargers
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Mark Fu is a Senior Marketing Director of Wired Connectivity Division at Cypress Semiconductor Corp. Mark is currently responsible for product marketing and business development for Cypress’s USB solutions, focusing on USB-C and Super Speed USB. Mark has 25 years of experience in the semiconductor industry across multiple disciplines, including ASIC design, hardware engineering, design verification, application engineering, product marketing, and business development. Mark holds BSEE and MSEE degrees, and he is an author of two patents.
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