Barrel Connector Replacement (BCR) Evaluation Kit from Cypress Semiconductor
Do you have a box at home that is full of chargers for different types of devices you own? It can be very frustrating trying to find the right charger in that mess. You can use Marie Kondo’s organization techniques to make your life easier or have less number of chargers and mysterious cables. Let’s be honest, ain’t nobody got time for "folding cables in tiny boxes and putting those boxes in larger boxes, and then coming up with categories to name them" as Marie suggests. On the other hand, hopefully, most of our devices would be able to share chargers soon.
A new standard for charging as well as data transfer, USB-C, has emerged a few years ago. Major companies, including Apple and Google, are now switching from old USB-A and USB-B to a new USB-C standard. The technology can achieve a transfer rate of 10 Gbps and power devices up to 100 Watts. If you have ever thought of buying the newest model of Macbook, you probably know that it has no other ports apart from USB-C. So, now we know that this is not another marketing strategy from Apple trying to sell expensive charging accessories.
Some of the electronic devices we use daily such as Bluetooth speakers and shavers are powered using DC barrel power adapters and the corresponding barrel connector. Barrel adapter’s plug is customized depending on the voltage and current requirement of the device. However, instead of increasing the collection of DC barrel power adapters in the “chargers” box mentioned previously, what if we could charge devices that originally were powered through barrel connectors with a USB-C power adapter? Cypress offers the EZ-PD Barrel Connector Replacement (BCR) Evaluation Kit (EVK) to convert electronic devices and power them from USB-C.
Figure 1. CY 4533 EZ-PDTM BCR Evaluation Kit
The EVK is based on Cypress’ Barrel Connector Replacement (BCR) controller (CYPD3177-24LQXQ). BCR controller negotiates for the voltage or current from USB-C power adapter dictated by the position of the switch. There are five different switch positions available which match the voltage rating of the external load. If the USB-C power adapter can provide the requested voltage, PMOSFET will allow the power to transfer to the output block terminal. The device with the barrel connector plug can be connected to the block terminal and be powered with the USB-C power adapter.
I performed a few experiments with the BCR EVK. The first one was quite easy, and I might have cheated a little bit. Surprisingly, I could not find that many devices powered with DC barrel around the house (I also did not want to ruin genuine chargers for those devices I have found just for the sake of an experiment). So, the first thing that came to my mind was to use one of the many USB-A to Micro USB-B cables that I own, which very conveniently can be used to charge Anker’s Portable Bluetooth speaker.
Figure 2. Anker Portable Speaker, CY4533 EVK with Micro USB-B cable, and Google 18W USB-C Power Adapter
Basically, there were three simple steps:
- I cut the USB-A to Micro USB-B cable so that the Micro USB-B side still connects to the speaker and stripped the wires.
- Next, I connected the power and ground wires to the positive and negative terminals of the terminal block J3, respectively.
- The voltage and current ratings of the speaker are 5V and 2A. Therefore, I have adjusted the switch position to be at position 1.
- Lastly, I have connected the 18W USB-C power adapter from Google to the board. And, voila’! Now, I can use my speaker even if I lose its original charger.
A few days later, I managed to find a Pure One Classic Series 2 Radio (apparently, I had not one, but two of these!) with a 5.5mm by 2.1mm power jack. But again, I could not demolish the original charger. Therefore, I bought a very inexpensive set of universal power adapter plugs which was very handy for the third experiment as well. Like the previous experiment with the portable speaker, I have connected the DC barrel connector to the CY4533 EVK and set the position of the switch to 3 (the voltage and current ratings of the radio are 12V and 2A).
Figure 3. Pure One Classic Series 2 Radio, CY4533 EVK with 5.5mm x 2.1mm DC barrel cable, and Google 18W USB-C Power Adapter
The question that came up almost straight away when I heard about this product was what if the voltage rating is not 5V, 9V, 12V, 15V or 20V? For example, I have a BT phone that needs 6V. One potential solution could be to use DC to DC step-down or step-up converters to match the voltage requirements. To test this out, I got hold of an adjustable step-down converter. I have configured it to convert 9V to 6V. I could not get exactly 6V, but I do not blame the converter given the cost. Once adjusted, the 9V output of EVK (switch position 2) went to the DC-DC step-down converter, which is then used to charge the BT phone with 6V.
Figure 4. BT phone, CY4533 EVK with 3.5mm x 1.35mm DC barrel cable, and Google 18W USB-C Power Adapter
Video demonstration of the experiment below: