Table of contents
▎Looking at the datasheet from the perspective of the project
The ability to read datasheets quickly is a basic quality that every engineer should possess.
Whether it is the model selection at the initial stage of the project, the subsequent software and hardware design, or the later stage of project debugging, engineers often worry about the English datasheet, such thick information, page by page, how long do they have to work overtime?
Although some semiconductor companies will translate their datasheets into Chinese, most of them are estimated to be translated by Google. There are many mistakes in it. Some just translate the headlines. The detailed descriptions behind are still in English, so it is better to read English directly . The original is reliable .
So how to find the most needed content in the shortest time? To put it simply, the datasheet includes performance introduction (what is the chip used for), pin definition (to draw a schematic diagram), internal register definition (to write a program), packaging form (to be asked in manufacturing and purchasing), these basic The information will be clearly written.
Also, as an engineer, you must be aware of the device's typical performance, minimum and maximum requirements and characteristics, what you can do without damaging it, and usage suggestions and hints.
▎Looking at the datasheet from the perspective of the project
Zhihu netizen Aisou mentioned in an answer how to look at Datasheet from the perspective of the project. The following excerpts are part of the content:
The first is device selection . In the preparatory stage of the project, device selection is an important work content. Correspondingly, there will be an introduction and feature list at the most eye-catching position of the datasheet of each chip, including basic content such as the supply voltage, current, power consumption, resources, packaging information, etc. of the device. Through these contents, we can quickly clarify the chip Function and field of use, to determine whether the chip can meet the needs of the project. In this way, we can quickly screen and complete the selection work.
After determining the device model, we will start the following design work. For hardware engineers, device packaging, pin allocation, and reference design are the first points to pay attention to. With these parts in place, the hardware engineer can start working right away.
Then some datasheets will considerately include the PCB layout of the reference board, and some will form this part of the content into a demo document separately. In the general part, such as power supply, reset, debugging circuit, etc., we can refer to these useful documents as much as possible, read the layout design guide in detail, reduce the risk in PCB layout and wiring, and increase the probability of a success.
Since the requirements of each project are different, there will be differences in the use of devices, so these differences from the reference design are the points we should focus on. We can search while designing. For example, you must be extra careful when pulling or floating specific pins. There are often some small traps in the handling of these pins. Generally, there will be clear instructions in the datasheet, which we need to read carefully.
The Datasheet often contains a lot of charts, and we can focus on them during the early hardware design. Such as the recommended parameters of the device, high and low level discrimination voltage, etc., these must be clear in the early stage of design.
Some device nonlinear parameters are illustrated graphically. For example, the on-resistance of a diode is different under different operating voltage conditions. This requires us to determine according to the requirements of different projects.
Some materials will use charts to illustrate device performance, and these also need to be paid attention to during the design phase. There are also some charts showing the test methods of the device, etc., which can be temporarily ignored in the early stage of design, and can be learned in detail when it is used.
In addition to the hardware content, the datasheet will also include the software part. The software part of different devices works very differently, and it is difficult to generalize. To master a basic principle is to put the priority first .
The main thing is to pay attention to the device's boot, reset, address space, debugging information, and so on. That is, the main part related to the normal operation of the device must first ensure that the device can work.
The second is the peripheral interface of the device and so on. The device can work normally, and we will debug each different module according to the introduction of the datasheet.
Basically, through the above content, we can complete the design.
However, the datasheets of many major manufacturers do not only include these contents. For example, some ADC/DAC device materials of ADI company also include the principle explanation of AD/DA conversion. These first-hand information related to chips are sometimes It is clearer than in the textbook. If we can study it carefully when we have time, it will undoubtedly be of great help to our design.
Datasheet can be a good helper for our design and a good material for learning.
▎ Take what you need
The deepest realm of reading a datasheet is not only to look at the content on the datasheet, but also to understand all the algorithms, protocols, and matching devices involved. You must be good at doing extended reading aids, and even see clearly the design philosophy behind the chip.
I heard that it takes three or four months to write a datasheet, and it takes four or five years to write a datasheet. The essence is actually incorporated.
Of course, the key points of information obtained by different occupations from the datasheet are different. Zhihu netizen Arthur Wang pointed out in an answer:
If you are IC design, you may pay more attention to the application note, diagram, reg file, which give you a reference for your design.
If you are a hardware engineer, you will pay attention to several chapters such as electrical characteristics, pin list, and package size.
If you are Marketing, you will pay attention to the feature list, reference design, electrical characteristics and other chapters.
If you are a software engineer, you need to read the chapter on registers and software.
If you are a project manager, you need to pay attention to all chapters.
If you are a student, treat it as technical English and practice reading.
Zhihu netizen Wellington Ritian believes that the chips that can be used are nothing more than the following:
The first type , those who make chips, those in the microelectronics and semiconductor industries, draw chip layouts, and understand the internal structure and functions of chips;
The second type is the application of chips, that is, to meet the needs of projects or products, chips are needed as a function of a certain link;
The third is to provide peripheral circuit support for the chip, layout and wiring, and draw circuit boards.
In addition , a more important job is to provide power solutions for chips, which may be the second type of engineer or the third type of engineer. In the electronic world of all kinds, the second type of engineers has the largest number of employees. There are pure hardware engineers, embedded software engineers, analog circuit engineers, and digital circuit engineers. What they have in common is application-oriented.
▎ last
Each company's datasheet has strict specifications and a unique style, sometimes interspersed with some principled introductions, even better than textbooks.
Beginners in design can start with typical chips and learn by analogy. But the datasheet is just a reference. To master the chip, it actually depends on the application, as well as the verification and debugging of the out of spec.
The datasheet is also one of the most accurate ways to understand a company's technology. Before the interview, some engineers will carefully read the datasheet on the company's official website, study the circuits used in it, and increase the probability of employment.