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Using Cheap Asian Electronic Modules By Jim Rowe USB Power Delivery Chargers Left-to-right: the Comsol COWCC30WH, XY-PDS100 & Belkin F7U060AU This article describes some low-cost modules that have appeared recently to take advantage of the dramatic growth in USB capability, especially in the area of power delivery (PD). This assortment includes PD chargers, cables and cable adaptors, while a follow-up article will look at ‘trigger’ or ‘decoy’ modules, used to configure the chargers, plus USB-PD testers. As mentioned in my recent article on the ‘USB Explosion!’ (June 2021; siliconchip.com.au/Series/367), one of the application areas of USB which has grown dramatically of late is the delivery of DC power. When USB first appeared in the late 1990s, it could provide just 5V of power at up to 100mA for a ‘low power’ device, or up to 500mA for a ‘high power’ device like a USB hard disk drive. But as the data transfer capabilities of USB were expanded via USB 2.0, USB 3.0 and finally USB-C, the power delivery capabilities were expanded as well. For an in-depth discussion of how USB PD works, see the article on that topic starting on page 36 of this issue. We’ll give a quick summary here, before moving on to describe the modules. USB 3.0 kept the 5V supply voltage but raised the ‘high-power’ current level to 900mA, allowing a downstream device to receive up to 4.5W (rather than just 2.5W). When the USB-PD (Power Delivery) specification was finalised in 2012, 42 Silicon Chip a device could receive 5V at up to 1.5A or 7.5W of power via a standard Type-A to Type-B USB cable. The smaller USB-C 24-pin connectors appeared in 2014, and when the USB-PD specification was further revised in 2014, 2016 and 2017, they increased the power delivery voltage and current levels as well. Now devices can request power at either 5V, 9V, 12V, 15V or 20V, and can draw up to 5A – corresponding to 100W with a 20V supply. And since the USB-PD 3.0 revision of 2017, devices can also take advantage of the programmable power supply (PPS) protocol, which allows variation of the supply voltage in 20mV steps. This expands the possible USB-PD applications dramatically, and that’s why we’re seeing so many low-cost modules designed to take advantage of this increased flexibility. How USB-PD works As mentioned earlier, this is described in detail on page 36. But there are some points that we can add here, and we will also summarise the basics of USB-PD negotiation. Fig.1: the USB-PD system consists of five elements: a primary DC power source, a USB-PD ‘manager’ with a downstream facing port (DFP), a USB-C cable, a trigger circuit fitted with an upstream facing port (UFP) and finally, the power ‘sink’. The USB-PD manager element could be combined with the primary DC source, and the trigger circuit may also be combined with the sink. Australia’s electronics magazine siliconchip.com.au Essentially, USB-PD is made possible by some of the extra contact pins in a USB-C connector. Specifically, the CC1 (A5) and CC2 (B5) pins, which are designated the Configuration Channel (CC) pins. The notional arrangement is shown in Fig.1. Initially, a USB-PD capable power supply sets its VBUS output voltage to 5V. It also ties each of the CC pins of its output (downstream) USB-C connector to a logic high level via a pull-up resistor Rp, with the value of Rp chosen according to the supply’s current capacity. Devices designed to receive their power from the USB-C connector are fitted with a pull-down resistor Rd connected between one of the CC pins and ground. The value of Rd is chosen to indicate the current level wanted by the device. As a result, when a cable from the device is plugged into the USB-C connector, the voltage drop on one of the CC lines indicates to the host that: • A load or ‘sink’ device has been connected. • The orientation of the USB-C plug in the connector. • The current available from the host supply. There is then an exchange of data packets between the supply and the load/sink via the CC line, using DC-coupled BMC (Biphase Mark Code) or Differential Manchester encoding. This allows the load device to indicate the supply voltage it wants, and then the supply to change its output to the requested level if it can do so. As mentioned above, if the supply supports the PPS protocol, the voltage can be adjusted in 20mV increments. This negotiation can only occur if the load device is connected to the supply via a USB-C connector and matching cable. It won’t work if a Type-A Using USB-PD for fast charging Even before the USB-PD specification was released in 2012, various firms associated with the burgeoning mobile phone market worked out ways to use USB sockets for fast-charging mobile phone batteries. Examples are Qualcomm, which had developed its Quick Charge (QC) protocol, Motorola with its TurboPower protocol and Huawei with its SuperCharge (SC) protocol. Perhaps because of the widespread application of these protocols, the various revisions of USB-PD gradually USB connector is used, because this lacks any CC pins or cable lines. The initial USB-PD Rev.1 specification of 2012 allowed a device connected to a host/power supply via USB 2.0/3.0 Type-A and Type-B connectors to negotiate a higher voltage than 5V (eg, 12V or 20V) using a binary FSK signal on the VBUS line. But this approach was deprecated when USB-PD Rev.2.0 was released in 2014. So most USB-PD power supplies can only deliver 5V (or perhaps 12V) via their USB Type-A downstream port or ports. Note that the USB-PD negotiation protocol allows for power to be transferred in either direction – from host to device or vice-versa. For example, a laptop or tablet PC can get its battery recharged quickly from a USB-PD power pack/charger by requesting that the charging be done at 9V, 15V or 20V instead of 5V. The XY-PDS100 quick charger This first module is a ‘fast charger’ that can be configured to give a range embodied them. As a result, when the USB-PD revision 3.0 was released in 2017, including PPS (Programmable Power Supply), it essentially incorporated just about all of the earlier fast charging protocols. So that’s why the specifications of most of the USB-PD trigger modules and fast chargers will claim compatibility with a list of protocols such as PD 2.0, PD 3.0, Qualcomm QC3.0 and QC4+, Huawei SCP/FCP, Apple 2.4A, Samsung AFC, MediaTek PE2.0 and PE3.0, Oppo’s VOOC and so on. of output voltages and currents using the standard USB-PD protocol. The XY-PDS100 comes in an extruded aluminium case measuring 53 x 46 x 21mm. It is available from several internet suppliers, including Banggood, which at the time of writing has it for US$13.10 plus US$3.30 for shipping. As shown in the photos, the output end of the XY-PDS100 has a USB Type-A socket and a USB-C socket, plus a 3-digit 7-segment LED display (with 6.5mm-high digits) and three indicator LEDs. One lights when the output voltage is displayed, one when it’s showing the current being drawn from the USB-C socket, and the third when showing the current drawn from the Type-A socket. At the ‘input’ end, there are two sockets. One is a small concentric DC socket designed to accept 12-28V DC from a mains power supply, and the other a USB-C socket marked “Input-PD”. On the underside of the case, the latter input has the legend “PD Recommended 87W”, but it seems The XY-PDS100 is shown at left connected to an XY-WPDT trigger unit. This trigger unit helps to set the provided charging profile for the input device by outputting a fixed voltage. At lower right is the rear of the XYPDS100; both these photos are shown at approximately life size. siliconchip.com.au Australia’s electronics magazine July 2021  43 Take care when buying USB-C cables and adaptors Although you will find many low-cost USB-C cables from vendors on the internet, you need to be careful when buying many of them. For example, quite a few of the low-cost cables are really only suitable for providing power and battery charging, not transferring data, and especially not highspeed data transfer. Apart from the lines involved in power transfer (including the configuration channel lines), they might not have any of the data transfer lines, except perhaps those for USB 2.0 (D+ and D−). This applies particularly for cables fitted with a Type-A plug at one end to be simply an alternative DC input. Essentially, what the XY-PDS100 does is convert a no-frills power supply with an output of 12-28V DC into a ‘smart’ USB-PD battery charger or power source, which can respond to the negotiation from a trigger unit to provide one of the standard charging voltage and current profiles. So it’s basically a programmable switch-mode step-down DC-to-DC converter, which can provide up to 100W of power at voltages between 5V and 20V from the USB-C output, or up to 36W of power at voltages between 5V and 12V from the USB Type-A output. And it even includes a three-digit LED readout displaying the current output voltage and current. Not bad for a very compact little unit that costs less than $25. Because the XY-PDS100 is a stepdown converter, it needs to have a DC input voltage at least 2V higher than the highest output voltage that could be requested. So if you only want a maximum of 12V for charging via the Type-A output, an input voltage of 14-15V would be fine. But for the full range of voltages required for USB-PD fast charging, the input voltage will need to be at least 22-23V. I was quite happy with the measured performance of the XY-PDS100. It seems quite compatible with the PD 3.0 protocols, and also with the PPS ‘vernier adjustment’ protocol. While the XY-PDS100 is a ‘USB-PD Manager’ module, needing an external DC supply, the remaining devices we’re going to look at combine both 44 Silicon Chip and a USB-C plug at the other. In fact, the presence of a Type-A plug is a strong indication that a cable is not suitable for high-speed data transfer, and quite possibly only for power transfer and charging. And the power transfer/charging will only be possible at 5V, since negotiation of a higher supply voltage probably won’t be possible. This also applies to the many nominal USB-C adaptors. If these have a USB Type-A plug or socket at one end, that means they are probably only suitable for use in power transfer and charging, although they might be OK for low-speed and full-speed USB functions, forming a complete USB-PD power source. I had some difficulty obtaining them, though. I ordered a couple of interesting units from a Chinese supplier, but they didn’t arrive, and I eventually discovered that they were out of stock. I had to get them from local suppliers instead, which turned up in a couple of working days, but they cost significantly more than the units I had ordered from China. The first one is... The Belkin F7U060AU 27W power adaptor This unit cost $39.95 from JB Hi-Fi (www.jbhifi.com.au). It measures just 51 x 60 x 31mm and weighs 50g. The unit is pictured in the rightmost photo at the start of this article; it has a two-pin mains plug on one end and a USB-C socket on the other end. That’s it – it’s just an elongated version of the familiar USB plugpack. The inscription on the plug end advises that it was designed in California and assembled in China. When I tried it out with a couple of different trigger units, I found that although it would register as a PD 3.0 device, it would only provide a choice of three output voltages: 5V, 9V or 12V. The two lower voltage settings can provide up to 3A of current, while the 12V setting can provide up to 2.25A. So the power rating of 27W only applies when the unit provides 9V or 12V; when it’s providing 5V, it is really a 15W source. Of course, this would Australia’s electronics magazine data transfer via the D+ and D– lines, assuming those wires are even fitted. Even if a low-cost cable has USB-C connectors at both ends, that is no guarantee that it is suitable for really high-speed data transfer. This makes it a bit risky buying these cables via the internet, because you can’t test them before you buy them. In fact, if you see one of these cables for less than $15, you can probably assume it’s only suitable for power transfer and battery charging. USB-C cables capable of being used for really high-speed data transfer are likely to cost significantly more than that. be fine if you only wanted up to 12V and 15-27W. The Comsol COWCC30WH 30W wall charger This unit cost $39.88 from Officeworks (www.officeworks.com.au/ shop/). It measures 44 x 64 x 40mm, and weighs 80g. As you can see from the leftmost photo at the start of this article, it’s very similar to the Belkin unit, with a two-pin mains plug at one end and a USB-C socket at the other end. The inscription on its plug end simply says “Made in China”. When I checked this unit with a couple of different trigger units, it only registered as a PD 2.0 device, but could provide any of the full five output voltages: 5V, 9V, 12V, 15V or 20V. As with the Belkin unit, it could provide up to 3A at 5V or 9V, but at 12V, it could provide up to 2.5A. Then at 15V, it could provide up to 2A, while at 20V, it could provide up to 1.5A. So it’s only a 30W power source for three of the five selectable voltages. Considering that its price is virtually the same as the Belkin unit, the fact that it provides a choice of the full five PD voltages, and with a nearly consistent power capability of 30W, makes it better value for money. The range of voltages and currents available from this type of charger means that it could power a wide range of devices, including those you might build yourself. If each of those devices contains circuitry to negotiate the current and voltage required, that means you could siliconchip.com.au have a small selection of power supplies to power a wide range of devices. So, in essence, these chargers could be the new ‘multi-voltage plugpack’ we all use in future. The ALOGIC WCG1X65-ANZ 65W wall charger The third USB-PD wall charger I bought is the ALOGIC WCG1X65, which again is very similar in size to the Belkin and Comsol units. It’s slightly smaller, measuring 55 x 60 x 35mm, and weighs close to 95g. This unit also came from JB Hi-Fi, at a cost of $74 plus delivery, but it is also available from TechBuy (www. techbuy.com.au), another local supplier, for $72.70 plus delivery. While it is almost twice the price of the other wall chargers, it boasts over twice the power capability at 65W. It comes with a 2m-long USB-C charging cable and a tiny (90 x 110mm) fourpage quick start guide. It also features a white LED power indicator, just below the USB-C output socket. When I checked this unit with the same trigger units as before, it registered as a PD 3.0 device and could easily be programmed to give any of the five standard PD voltages: 5V, 9V, 12V, 15V or 20V. And it can provide up to 3A at any of the four lower voltages, or up to 3.25A at 20V, which is pretty impressive considering its compact size and weight. The makers claim that this is a result of using “the latest GaN charging technology”. Presumably, they are taking advantage of the ability of transistors and diodes using gallium nitride (GaN) substrates to operate at much higher voltages and with higher efficiency. So if you need a USB-PD wall charger capable of supplying up to 65W of power at any of the five PD 3.0 voltage levels, the ALOGIC WCG1X65-ANZ would be the best choice despite its significantly higher cost. Note that one of the devices that I tried and failed to source from China was the Bakeey HC-652CA 65W wall charger, which would probably also be a good choice, if and when it becomes SC available. USB-C breakout boards Because of the possible problems associated with USB-C cables, you might be interested in the low-cost ‘breakout’ module or test board shown in the photo below. It is available from internet suppliers like Banggood for only US$2.10 for a single, US$4.80 for a pack of five or US$9.00 for a pack of ten (all plus shipping, of US$3.30 in each case). This module’s PCB measures only 25 x 40mm and has a USB-C socket mounted at the centre of one of the 40mm sides. All 24 of the socket’s connections are brought out to two rows of 12 solder pads at the opposite edge of the PCB, with one row (A1-12) on the top and the other (B1-12) underneath. The socket’s metal frame is also brought out to a further “G” pad on each side of the PCB. A pair of these ‘breakout’ boards make it easy to test all of the lines and connections in a USB-C cable. I bought a pack of five, but wasn’t too impressed with the soldering for the 24 very closely spaced pins of the sockets; one of them seemed to have a dry joint or two. Since it would not be easy to repair these joints manually because of the very close spacing (about 0.5mm), I decided that the board concerned was throw-away material. So be warned! In the following article, we’ll be taking a look at some of the low-cost USB PD ‘trigger’ modules that can be used to set the output voltage and current of USB power supplies, like the ones described here. Useful links USB-C: https://w.wiki/nto USB-PD: https://w.wiki/34dT siliconchip.com.au/link/ab7l Quick Charge: https://w.wiki/34dU Gallium nitride: https://w.wiki/34dV siliconchip.com.au The ALOGIC WCG1X65-ANZ 65W wall charger, shown enlarged for clarity. It registers as a PD 3.0 compliant device, and therefore can provide the standard voltages of 5V, 9V, 12V, 15V & 20V at 3A (or 3.25A for 20V). As the output power increases, these chargers can become quite costly. Australia’s electronics magazine July 2021  45