Shenzhen circuit board manufacturer ranking

As a cyborg, we have to interact with different circuits, but there are some circuits that are classic and worth remembering forever.

The circuit is used to Sample the circuit before various ADC, which enables ADC to realize the rail to rail input. The working voltage of the sample circuit is * over Vdd, which greatly reduces the setting time, and there is almost no reliability problem. No part of the circuit can be reduced or changed in position. This circuit directly led to the development of ADC and is now almost standard in all ADCs except Delta Σ, becoming one of the classic analog circuits in history. Of course, the circuitry is not easy to understand at first glance.

A magical source of electricity

Input 'any' current. (quote meaning, any current value of a reasonable size), the output will be approximately 2ln8Vt/R.

The working principle is as follows:

Each clock, the comparator compares the voltage on the capacitor to the ground, and the result determines whether the next capacitor is connected to the circuit.

It's essentially a dichotomy to approximate an unknown voltage.

CMFB of switch cap

CMFB is implemented with only 4 capacitors and 6 switches, which is very simple and hardly affects OPAM specs like output swing, gain, etc., very simple.

Data Weighted Averaging

The basic idea is to * go through each current element in DAC to reduce the impact of current element mismatch on the signal-to-noise ratio of ADC. It is very clever to realize the first order noise shaping of current element mismatch only through several simple digital modules.

H bridge circuit

Drive motor reverses, no problem is easy to use and affordable, buy a driver chip money enough to build ten Bridges. And with the market common audion can be done, the power is a little larger, the MOS tube on the line.

Green color is welding resistance ink, the main components are resin, talc and pigment, the current market is more competitive mainly Japan taiyo, Taiwan South Asia resin, Taiwan Changxing Chemical industry, Taiwan Yongshengtai ink, the price is generally 60~120 yuan/kg; Of course there are other colors, such as red, black and so on. Green is widely used.

On this question (why is the circuit board mostly green?) There are several ways to say:

Point of view 1, Generally speaking, the whole electronic board level products have to go through the process of board making and Posting. In the process of board making, there are several processes to go through the yellow light room. The visual effect of green in the yellow light room is better, but this is not the main.

During SMT welding, it is necessary to go through tinning, Posting and AOI verification. These processes should be calibrated by optical positioning. Green background color has better recognition effect on the instrument.

Opinion 2, the common red, yellow, green, blue and black, due to the problem of the process, a lot of line inspection or rely on workers to see with the eyes (of course, most of the flying needle test now). Keep looking at the board with bright eyes, which is a very tiring job oh, green relatively does not hurt the eyes, so most use green.

Blue and black, because they are mixed with cobalt and carbon respectively, have certain electrical conductivity, so there is a risk of short circuit. Green PCB is more environmentally friendly, will not release toxic gas when used in high temperature environment.

Around 2007, people began to pay attention to the color of PCB board, mainly because the board type of Asus, Microstar, these big factories have adopted black PCB board color design, so people gradually believe that the PCB color is black. Since then, more and more manufacturers have begun to use black PCB coating - can be said to be an inexplicable reason for such an inexplicable phenomenon. No one has ever said that if PCB color is black, the quality of the motherboard must be good. This is the product misdirection caused by using black to identify product positioning. Indeed, black PCB is able to show its own technical strength, because black PCB is not easy to see the line, so whether the design or after-sales will suffer from the cost pressure, and the technical strength of the board card manufacturers using black PCB tone is not because black can improve the performance of the motherboard, From the point of view of rational analysis also know that color alone can not improve the performance of the board.