Common interface standards can improve the convenience of life, such as powering desk lamps, drones, TVs, printers, external GPUs and even sweepers

First of all, the power is not pulled up casually. Power is equal to voltage * current, neither of which can be amplified casually. The current is actually limited by fire safety. With the same resistivity, the higher the current, the hotter the wire will be. If the heat exceeds the natural heat dissipation capacity, it will heat up, and it will burn if the temperature rises high. Therefore, the maximum current is limited by the resistivity of the entire wire. This whole line includes the cable itself and the plugs on both sides and the sockets connected to it. There is still room for adjusting the cable thickness and fineness. The plug and socket are regulated according to the standard and cannot be adjusted. If the adjustment exceeds the allowable error range, it is not easy to use. Therefore, the current agreement to 5A is already very large. Physically, all core wires can be used up to about 10A, and they have to be made of very expensive materials, which will not be easy to use. The voltage is limited by physical safety, that is, the risk of breakdown. Of course, it also involves fire prevention and protection against electric shock. Simply put, you feel that the line is insulated, but it can only isolate a limited voltage. If it exceeds the voltage, it may break down and discharge. In the shortest case, it will cause the line to short-circuit and burn the equipment, and in the worst case, it will catch fire. The limiting factor of the maximum voltage is mainly the plug and socket, because the standard plug design determines the line width and the distance between the golden finger, the voltage difference is very limited. The voltage currently given is 20V, which is actually almost the peak value under safe conditions. After all, considering the safety of the human body, it is about 30V. So in fact, the current PD standard basically provides the upper limit of the power that a line can provide, which is about 100W. Of course, it’s not impossible to have crazy stack technology to increase the total power. For example, a total of 24 lines of USB Type-C, if I use all 6 groups to supply power, I am afraid it can indeed exceed 300W (but it can’t exceed that much, the cable The total power is still limited). But what is the point of doing so? It also provides 300W of power, and the cost of an ordinary mains cable is only about one-tenth of that of a USB Type-C cable of the same power. Manufacturers and consumers need a USB Type-C cable that can supply power because it can solve power supply and high-speed data at the same time with one cable, which is simple and convenient. At the same time, applications that only require a power supply function or only a data function can use part of the hardware to reduce the total investment. But this demand or the corresponding benefits are not available everywhere. For example, why do I need to use high-power USB Type-C for desk lamps? Is there a situation that requires desk lamps and other equipment to transmit data? Is there a situation where a single wire is required for the desk lamp and other equipment? Taking a step back, how much power does the desk lamp have, can’t 100W satisfy it? As for drones, why do we need 300W? Ordinary battery packs simply cannot be charged with such high power. TVs and printers are fixed devices, why do they need to use USB Type-C to power them? They should be able to power my mobile devices with USB to reduce the total cost. In fact, many products also do this. The same is true for an external GPU. The GPU most likely needs to be connected to a display device. If the display device is not too big to be moved, it may not need an external GPU. As long as the display device supplies power to it—but USB Type-C can afford it. The power is not enough. At this time, using independent power supply will not cause obvious inconvenience, so you have to plug the external GPU into the mains and then supply power to the mobile device. Anyway, in the final analysis, the answer to this question is basically a combination of two reasons: too expensive, no one buys it.

zhiwo

By zhiwo

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helpmekim
8 months ago

Because these devices can be plugged directly… In fact, USB is used for charging. It is a strange thing. The fundamental reason why USB is used for charging is that many electronic devices cannot be charged with too high AC power and need to be lowered. It is obviously a wasteful behavior to equip each electronic device with a huge charging head, so people need a general-purpose, low-voltage power supply, and then there is a market for USB charging. Even if USB supports a charging power of 300W, it is meaningless, because devices that provide USB power supply usually cannot support such a large power, such as a power bank. 300W of power is enough to generate heat until it explodes. So even if it is designed, most power supplies and equipment cannot support it, making it meaningless. High-power electrical appliances can already be plugged directly into the plug… 300W of power, under the condition of city power 220V, already needs more than 1A of current, which is not a small number… Finally, I want to remind many people one thing Now, the battery with the highest energy density, that is, the highest energy density of lithium batteries is 900,000 J/kg. What does this mean? This means that if a gadget has 300W, it needs a kilogram of battery to power it for 50 minutes. Note that this is still a bare battery, excluding the circuit and casing. In other words, if your power bank can achieve an output power of 300W for one hour, your power bank cannot weigh less than three or four kilograms… the same is true for a notebook… a 20,000 mAh power bank with a power of 300W The output power cannot be maintained for more than fifteen minutes.

heloword
8 months ago

The physical structure of the connector determines that its withstand voltage and withstand current have upper limits. The top grid power supply is 20V 5A, the four power pins of USB-C, and the electrical load of a single pin is 20V 1.25A, which is close to the design safety limit of 30V 1.5A. As for low-voltage electrical appliances such as low-end desktop computers, the household centralized 12V DC transmission and distribution system should be more popular. Each household installs a large-capacity 13.8V high-efficiency switching power supply, and uses 15A or more connectors to provide these low-voltage Equipment power supply.

helpyme
8 months ago

The first is the basic physics knowledge: power P = voltage U × current I is now known that the required power is 300W, the voltage is 20V (the mainstream voltage of notebook computers), what is the current? The answer is 15A, which is undoubtedly a relatively large current value. Knowledge point: For power supply cables, if they want to carry more current, they need a larger cross-sectional area. The larger the cross-sectional area, the greater the charging current that the data line can carry, the smaller the impedance, and the smaller the heat generation— —In simple terms, the thicker the wire, the more current it can withstand. Generally speaking, in order to transmit 15A current stably without excessive temperature rise, the cross-sectional area of the cable needs to be no less than 2.5 square millimeters, and the Type-C interface is small, and the corresponding cable cross-section is even smaller There is no way to make the thread so thick. In general, the current Type-C can achieve 100W (20V*5A) power supply, which is already a relatively balanced choice after considering the needs of size, price, and power supply capacity.

sina156
8 months ago

In terms of technical implementation, other respondents have already made it very clear. I would like to think about it from the perspective of product positioning: Why do you want to do it? What pain points have been solved? You were eating chicken on a desktop computer. In the final round, your dad came over to “charge my phone” and unplugged the type c cable of your computer… Can the sweeping robot be plugged into the computer to charge? Sorry I don’t know what the requirement is. Can the vacuum cleaner be plugged into the computer to vacuum? Plug the rice cooker into the computer to cook rice? Where is the meaning? How do you feel that the power supply of these high-power electrical appliances is removed and disguised as a USB charging head (300W should be called a charging brick), which solves a non-existent problem? If it is for versatility, is the versatility of type c power supply stronger than power plugs? The maximum power of 100W has covered most of the devices that need to use USB, and the cost can’t stand it, and the audience is also very small.

yahoo898
8 months ago

First: Not to mention other things, just say 300W if it is really arranged, then someone will say that it is tasteless-why not 500W, 1000W? People’s hearts are endless [Biao Liao Laughter] Second: I still say that if 300W is really arranged, do you know any desktop computers with real power lower than 300W? You do not know! Most people don’t know the daily power and peak power of their desktop computers. If you plug in USB-C indiscriminately at that time, who is responsible for the broken computer? The power range of drones, desk lamps, TVs, and external GPUs is even more chaotic. Third: It is not cost-effective commercially. After all, there may not be as many devices that want to use USB-C power supply. If USB-C is to meet the 300W power supply demand, the requirements for workmanship will be very high, and the price will be much more expensive-you are sure you would rather spend 50 yuan Buy a USB-C power cord instead of a 10 yuan 220V ordinary power cord? Even now, most of the USB-C cables on the market do not meet the 100W power supply standard, because the cost reduction design (cutting corners) is aimed at lowering the price. As for whether it can be technically realized, that is another matter. Many things can be achieved without technical problems. Whether there is commercial value and whether there will be additional side effects, this is the real question.

leexin
8 months ago

I guess the respondent should not have the experience of plugging ten computers, 6 monitors, and three light cats in the study, otherwise he would not ask this question. I guess the respondent should only have one device of each type, and the total cost is not high. , So I haven’t considered other issues other than convenience. The core of this problem is the versatile cable, cost flying, residual blood cable, convenience explosion. First, and most importantly, when the number of your equipment increases, just for convenience A demand for sex, the cost paid increases linearly with the increase in the number of equipment. Take these ten computers as an example. I don’t have eight ears and cannot listen to 8 channels of sound at the same time, so I only need 1-2 computers to be able to produce sound. The audio system attached to the remaining 8 computers is just for me. Totally worthless cumbersome. Generally a better motherboard, the audio system will cost about 20-30 RMB in material cost. Eight computers are the cost of RMB 240. As the number of computers increases, this cost increases linearly. If the low-power devices (each device power consumption is less than 30w) are replaced with USB-C, it is no problem, but the cost is one yuan more than micro usb, and the price increases by two yuan. This is easy to say. However, if it involves higher-value electronic products, the accounting is not the same. First of all, you need to calculate how much your full-featured USB port needs to achieve all the functions. We assume that a computer has a full-featured USB interface, which can form a lightning grid bridge, can be connected to an eGPU, can transmit 100w of power, and can also be used as an ordinary USB interface to achieve video output. And I also assume that this versatile USB interface does not require an additional main control, the core main control is all integrated in the chipset. To achieve video output, DP ALTmode is required, and an additional small main control is needed. It doesn’t matter. VIA, about three dollars to achieve 100w power supply, requires USB PD, and a power management chip that supports PD, which is not very It doesn’t matter, it’s even three dollars. Then, suppose this machine is an MXM independent display or a set display. In short, it cannot be a standard HHHL or FLFH card. Otherwise, the material cost of the video signal input port must be added. Finally, suppose this machine There is no need to supply power to the external device, that is, the device itself is a complete system. In order to realize the USB universal, you need to pay a material cost of at least 6 US dollars. If you calculate according to the general cost/price ratio, consumers need to pay 12 US dollars . If ten units are 120 dollars. This is the ideal situation. This is just to achieve the cost of a full-featured USB interface, which can neither be connected to the device nor included in the price of the power supply. If you want to use this port to connect to a high-speed device, we assume that an external graphics card is connected, and this interface has 80Gbps, which is pcie4.0X4 Around the speed. Then another problem arises: signal integrity. PCI-E 4.0 uses a high-quality PCB that is up to 25.4 cm, a transmission distance of 10 inches, and one connector. If USB wants to achieve the transmission speed of PCIE4.0, and does not add retimer/redriver, then the wire length is 25 cm. Basically no practical value. And the USB connection is not through one connector, but through two connectors. The effective transmission distance should be shorter. Then you need to add a retimer/redriver, this kind of active cable, the price of 2 meters, we calculate it at 100 dollars. In other words, before buying the graphics card box, consumers will have to pay an extra $112 just to meet the demand for USB-C to connect to the independent display. The other cost of the graphics card box, we calculated as Taobao copycat, 50 US dollars, which does not include the second power supply for the graphics card, that is, the single card power consumption is less than 100w. In other words, in order to satisfy the USB-C connection independent display, on the basis of already very mature technology and supply, consumers have to pay 150+ dollars intermittently. If you want to connect the Universal USB0 to the eGPU at the same time, connect the Universal USB1 to the external disk array, and then connect the USB-C from the graphics card to the monitor, then the price of this function is not 150+ dollars, almost doubled to 300 dollars. If you have to unify the cables, the price will soar to nearly $400. If you do not unify the cables, use the active mode for the eGPU line and the disk array line, and use the passive mode for the display line, then you will face greater inconvenience than connecting the DP/HDMI signal line alone: ​​at least a separate signal cable At a glance, you can know whether the monitor is connected to other devices. If it is a C port cable, the pure power source can only use USB2.0. The non-active can only connect to the display. Only the active line can provide high-speed data and connect to the display. Power supply If you have two, it is 112 (device 0) + 112 (device 1) + 50 (eGPU box) + 50 (external disk array) + 100 (2 meters active cable-device 0 to eGPU) + 100 ( 2m active cable device 0 to external disk array) +100 (2m active cable device 0 to device 1 thunder grid bridge) +100 (2m active cable eGPU to display) Good guy, 600-700 dollars, the cost is already Can buy a 3080. If you just give up the so-called one-line communication and USB-based modularity, you can save a 3080. This model does not involve the cost of power supply. The subject says that the cost of 300W pd, if all are counted, you can buy 3090. Up.

greatword
8 months ago

This is a very interesting question, I am entertaining to do the math. Just write a joke. Because the material properties of copper can’t reach 300 watts. If it reaches 300 watts, the temperature of the copper wire in USB C will reach 310 degrees. It should turn off the circuit board directly. The USB c interface is like the picture below (from ST Electronics). There are many interfaces, but in fact, only Vbus can supply power. That is, looking at so many lines, only 4 can be used for charging. If you want to minimize the heating of 300 watts, H=(I^2)R*t R=V/I, then 17.4V and 17.4A are required. Source: USB.org According to the picture above, Vbus has a maximum width of 1.25 mm and a maximum height of 35 microns. Four bars are 5 millimeters. The shortest length is 8 mm. (Actually, under this voltage and current, there is no difference between more or less millimeters.) Using IPC-2221 standard calculation, when you don’t plug it in, the temperature of the copper wire on the power supply directly rises to at least 64 degrees. Then you take the heat-insulated gloves and put this thread on your hand and insert your phone. You will immediately find that the temperature rises directly to 310 degrees Celsius when there is no air to dissipate heat. Is this temperature different from the heating wire? Of course, the melting point of copper has not yet been reached, but it is more than enough to heat the circuit board. Of course, this is not rigorous, and the calculation formula of IPC at high temperature is not applicable. The copper industry does not have sufficiently high thermal stability, thermal expansion coefficient, Young’s coefficient and so on. The resistance at high temperature cannot be calculated in this way either. (Of course I will not build a model for the sake of a joke, just write a joke) But in a nutshell, I want to tell you that unless superconducting is used, 4 such thin connecting wires, 300 watts will directly become 310 degrees Celsius heating wire. Of course, if the interface can be changed, it is also possible to make 12-16 of the 24 wires into power supply wires, and to use a low-resistance material such as silver. (Of course, I don’t know how to ensure data transmission compatibility.)

loveyou
8 months ago

Physical limitation: If the current is 5a when the power is 300w, the voltage is too dangerous to reach 60v in this narrow distance, it is prone to electrochemical corrosion, or even arcing and fire. If the voltage of a 20V circuit will reach 30a, how thick the wire core needs to be, it is almost as thick as the last joint of your little finger, and then the interface cannot withstand it and burns. You can check that the 30a connectors are bulky and thick. Yes, because the heating is the square of the current, the heating of 30a current is 36 times that of 5a in the same state. Market restriction: Technically, both sides can be balanced to achieve greater power, but once the power is set too large and the cost remains high, manufacturers will abandon this solution and switch to a lower cost solution. For the communication bus, there is not only a usb, but also a lot of eye-catching. In the past, 1394, Apple’s dp, etc., once you are abandoned by the market, someone will immediately insert it. Power limit: In terms of power, any data will be stuck. Because the demand for power is unlimited, so how much power will be dismissed, if you want 300, others will want 500, and if there are 500 others, they will all want 1000, so in terms of cost technology Waiting to find a reasonable limit is the optimal solution Type-C: 5a is set because the current that the four pins can withstand is about 5a, and the wire should be thicker after 5a. Extended upgrade: How to increase the power supply under current conditions? The first is to make full use of the existing connection metal points, change all the eight pins of the internal power supply to positive, and then use the outer shell as the negative, so that the current can be increased from five amps to about seven amps (think about why), and then specify The rubber core uses ceramics instead of plastics, and some ceramics are used to pinch the plugs, which can easily and quickly dissipate the heat from the joints. Then the power cord uses silica gel as the shell material. By the way, another wave of current is increased, so that the interface current can reach more than 8a. . The insulation material with better thermal conductivity is used on the wire, so that the heat of the wire can be quickly dissipated, and a larger current can be passed with a thinner wire. Regarding the voltage, the human body safety voltage is set as the upper limit, and 35v is set as the highest voltage. Then the maximum transmission power can reach 280w.

strongman
8 months ago

Technical problems are not a problem. The voltage is 20 to 30, and the dual interfaces are connected in parallel, and it will be 300 watts immediately. Then came the problem. The desk lamp that plugs in AC is sold at 175, and the plug with 3.0 is sold at 195, and you have to bring your own 3.0 adapter. Which one do you buy? The AC plugged TV sells 4888, and the 3.0 plugged TV sells 5299 (including adapter). Which one do you buy? 500W desktop switching power supply sells 299, 300W 3.0 power supply sells 699, and another 299 DC-DC converter board, which one do you buy? 3.0 interface printers, speakers, desk lamps, desk fans, humidifiers, air purifiers, fresh air fans, toilet seats, vacuum cleaners, robots, electric wipes, do not come with 3.0 adapters, you probably need to buy a charging head, just said For each 699 of 300 watts, how many do you buy? Let’s say it is done, set up a paper, open a crowdfunding, pay the money first, can’t go back.

stockin
8 months ago

First of all, this kind of power supply line of the USB-C port, the pressure is very large and it is easy to cause problems when running to 5A. The safe current that is not a problem with just finding a line is only 2A, which means you must have a voltage of 150V. Only a USB-C can be used, otherwise it is very likely that you buy a garbage cable and burn it directly. This is no joke and you need a 300W switching current, which is basically a small brick. , The minimum price is 100 yuan, if you want to make it smaller, it will directly exceed 200 yuan, and then there is a high calorific value and a large number of electrical appliances in the computer, the actual working voltage is very low, let’s say 12V is good, 150V 2A DC-DC to 12V 25A, it needs a step-down circuit and a heat dissipation module the size of a small mouse, and then the heat generation is not small, the failure rate will not be too low, the cost is dozens of dollars and we finally spent 300 yuan Money, there is no built-in switching power supply for a garbage of 50 yuan, so it is easy to break. Isn’t it a disease…

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