Shenzhen's original closed area is a narrow zone, east and west, north and south. There are three ways to connect this area, and the south is Binhai Avenue. The middle is Shennan Avenue. The north is the North Ring Road. These three avenues will be integrated with the moon bay avenue after the west, but their respective fusion methods have different. Binhai Avenue and Moon Bay Avenue is a completely vertical relationship. The North Ring Avenue and the moon Bay Avenue are each bending to form a slash connection from the north to the west of the west. There is no abrupt feeling, Shennan Avenue in South Head ancient city and southern middle school abducted a bend and extended to the northwest and 107 National Highway. These two slashs just cross-crossing, constitute a cross-shaped transportation hub - Deep South and North Rongshang, let various vehicles can freely switch between the various avenues, but because large vehicles are banned from crossing the urban area through Shennan Avenue, they can only drive on the North Ring, 107 and Moon Bay Avenue.
Affected by the surrounding terrain, there is a corner of 90 degrees in the above cross-shaped transportation hub. It is a counterpart road from the North Ring Avenue to the West Road, and the various types of vehicles will turn through it. Therefore, it is necessary to hide a lot of risks, driving through the drivers here is especially careful, do not grab the road with large vehicles, it is best to stay far away from them. Some acute children may also want to overtake here. I feel a little adventure, because once I affected the operation of large vehicles, I want to slow down, avoid it is very dangerous, and it is very dangerous. As a driver who has often passed this intersection, I often analyze the road situations similar to the above-mentioned roads when driving on the road. A lot of traffic accidents may be prevented in advance, so though There have been more than 20 years of driving age, but because the traffic accidents brought by your own responsibility have little happened, the money to buy insurance is almost white, so now I will sell the third time now. Liability insurance and must buy a strong insurance, completely don't worry, because of your responsibility, you can save the car every year.
In fact, when we drive on the road, we not only need to prevent the big trucks may give yourself, the car is also needed. I met a car suddenly in my left side when I turned it. The front swings, as if its driver is drunk, my direct reaction is immediate slow down and it pulls the distance, although it is stable after the second swing, but still keeps a distance from it until After arriving in the straight line, accelerate the front of it, put the length of the time in parallel with it, and passed the dangerous road section.
Cars is a good means of transportation, due to roads, vehicles, drivers or other factors often happen, thereby causing damage to relevant personnel and materials, and thus It is necessary to maintain a very rigorous attitude to participate, prevention of possible traffic accidents, and minimize possible loss damage to minimal. If an accident occurs, we should also help yourself to save yourself, with items such as lighting, glass breaking hammer and medical rescue materials on my car, but they have never been used, but It is always ready, just to prevent the problems that may happen.
The car is a tool, and the problem has occurred in use. It cannot be exercised normally, which is the failure state of the car. What impact may be caused by these failure states, which is a problem that needs to be considered for the utility analysis of the failure state. According to the effect analysis of the failure state, one is to make the failure state as little as possible, and the other is that it can minimize it when it occurs, and the cost can reduce the cost of preventing precautions. I decreased the cost of purchasing insurance, and the role is huge, and this does not include the joint income such as family's peace of mind.
The safety of the vehicle is so important to us, and the electronic device used for vehicles naturally needs high security, otherwise it is possible to cause the failure and / or safety accident of the vehicle because of its own reasons, such as failure. Electronic devices may cause serious safety accidents such as vehicles, and may even have serious safety accidents such as spontaneous combustion, bring serious damage and loss to our lives and property. Based on this consideration, you can analyze the possible malfunction, failure of the power supply in the use, analyze the impact of them, and take precautions to avoid problems in advance, reduce the problem of loss after problems. This is the so-called FMEA, and its focus is prevention in advance, not follow-up. FMEA comes from Failure Mode and Effects Analysis, It is used to translate into failure mode and its impact analysis. I am used to using the effect, I will use it naturally. This will not cause the reader's doubts.
We mentioned that the motorcycle RTQ2960-QA ~ RTQ2965-QA series of high-pressure BUCK converters RTQ2960-QA ~ RTQ2965-QA series is mentioned in the FMEA failure mode and its utility analysis results, now Just look at some simple perspective, what is its pin design, see if they really have the role of preventing problems.
This is a pin arrangement of RTQ2960-QA encapsulated by WDFN. These pins are described in the specification:
This makes it possible, it can be known that the VIN, EN, SW together can withstand the voltage of 65V, and the maximum pressure difference between the BOOT pin and the SW pin can reach 6V, indicating that it can withstand higher Voltage, so when RTQ2960-QA works at its highest input voltage 60V, there is a very serious problem that there is a short circuit that will have adjacent pins.
Now consider a relatively extreme condition, because the SW pin is adjacent to the GND pin, if they are short, the voltage of the output is inevitable due to SW and the ground circuit, the output voltage cannot be maintained normally, which will result The result of pressure protection. Another aspect needs to be seen. If there is a state in which the upper bridge MOSFET is in turn on, there will be a large current flow through its drain and source channel, and will soon exceed it. The overcurrent limit threshold, and this will trigger an overcurrent protection action, which will immediately cut the upper bridge switch. If the upper bridge switch does not have time to cut off because it is too hot, the high temperature formed in an instant is also blown up without sustaining the condition of the current, so that it can avoid due to the continuous accumulation of heat. Burning problem.
Now let's take a look at the design specification of the EN pin:
As long as the input voltage of the EN end exceeds 1.25V (rated value), RTQ2960-QA is enabled, if other conditions have already been included, the normal work of IC will start now, but why can it withstand 65V voltage? One of the reasons is probably because it is just in VIN and other low-voltage pins that can resist high pressure, in case it and the VIN short circuit, such a design can ensure that it will not be damaged, it also brings the easiest power-up startup Effect. In the application of timing design, the status of the EN and VIN short circuits may also appear because the EN does not withstand the results of the high pressure, and now the design can The problem is also included.
For systems with fault tolerance, when an unexpected condition occurs, the function failure of IC is acceptable, which cannot be uncontrollable, because the impact of failure can be controlled. In the range acceptable, within the range, it is not exceeded by our estimates, and the effects of combustion are difficult to previse. In the past, I have faced the design cases of some Japanese companies with customers. Seeing that they will have some special practices for some places involving security issues. For example, we will see an external connection in the above schematic. Different diodes, they may use two pipes here to be connected in parallel, extremely, may even be two series of two in parallel with other parallels, the purpose is to solve a diode open or short circuit. The normal work problem is avoided because of a small problem, this practice looks a bit extreme, but it contains very special pursuit, it is worth learning in some cases.
The above content is a statement made from how I see how FMEA acts in IC design. It is a response to the question of readers after the previous article released, purely personal opinions, not necessarily right, for reference only.
Reprinted from Richtektechnology.
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