How do PCB design digital analog connect

Some customers have consulted our company about PCBA processing and long-term cooperation. After detailed consultation, they said they should consider it. Today, we will talk about why customers hesitate to choose PCBA processing suppliers and how to choose a reliable supplier that can cooperate with us for a long time. Faced with tens of thousands of suppliers, how do we choose the supplier we are satisfied with? The following patch processing manufacturers to explain how to choose Pcba processing suppliers and PCB design digital simulation how to connect the relevant knowledge.

1. How to connect digital and analog PCB design

First, let's take a look at why digitally and numerically PCB design engineers are interested. Much of this is derived from the names of the power and ground pins of components such as ADCs. In fact, analog and digital pin names indicate the role of the internal element itself, but do not necessarily mean that the external should do as the internal role.

In order to avoid the coupling of digital signals to the analog circuit, the digital ground and the analog ground are separated. I personally think it is a partition, but the internal digital ground is connected. I have measured some chips with a multimeter, such as ADV7180, KS8995, TLK2541 and so on, and the internal is connected. Let's talk about the advantages and disadvantages of the above two kinds of connection: using inductance or magnetic bead connection as the name means that the digital or magnetic bead is connected at a certain point on the PCB board, which seems to solve the digital signal interference analog circuit, but it has created a new problem -EMI.

High frequency electrostatic discharge interferes with the current flowing through the inductor or magnetic bead, resulting in a voltage drop at both ends of the inductor or magnetic bead. In a high voltage test, the voltage at both ends is too high and cannot be quickly released to the bottom, which may damage the chip or restart the device. Personally, I prefer direct connection or bridge connection, which also solves the loop problem, avoids generating radiation, digital and analog ground equipotential, and has no voltage drop or very little, so that when doing high voltage test, the equipment will not be affected or the chip will be damaged. Just pay attention to the proper zoning or trench bridge connection. The premise of this method is to do a good digital - analog partition. But the power supply still needs to be separated, it is safer to use a separate power supply, but the cost increases. It is commonly used to use a ferrite ring to separate the analog and digital power sources.

The best joint point of digital ground and analog ground is generally at the entrance of the power supply, so that the coupling between the analog loop and the digital loop is minimal, and the interference of the digital circuit to the analog circuit is minimal. If the segmentation plane is done well, the drive current and the loop current of both are not interspersed with each other, there will be no large current loop. This is the basic principle, but in the practical application is very difficult, difficult in the analog and digital part of the cross connection, there is no way to separate the two actually separated, if the two forced isolation on the reference surface, is bound to cause a large current loop, the effect is not as good as not divided. Therefore, in practice, special care should be taken to choose the form and part of the segmentation, that is, to make the two better isolation, without hindering the flow of the drive current and the loop current. The advantage of using inductor or magnetic bead as connection is that it can isolate the high frequency noise of the digital part and keep the analog circuit clean.

2. How to select Pcba processing suppliers

I. Perfect industry qualification. ISO9001 qualification certification, this is the state for PCBA manufacturers very basic processing technology, environment and other primary assessment. A higher level or more professional qualification

Ii. Professional engineering procurement team. People are productive forces. Professional high-tech engineering, procurement team, for customer product production process control and quality control must be for customers to save worry, time, labor, money. If a PCBA processing plant does not have an experienced engineer, you have worked hard to develop the product into the hands of a group of foot jerk, the consequences are unimaginable.

Third, first-class production equipment and testing equipment. Why the first-class production equipment and testing equipment, this is the abbreviation of the two kinds of equipment. Many PCBA factories secretly change the concept, saying that they have first-class production equipment, there is no advanced testing equipment to mention, I can do anything. But those in the know know that as new products and processes are introduced, new products are becoming more and more integrated, smaller and more sophisticated. The slightest mistake is the whole batch of bad, no advanced testing equipment, simply can not cope with, let alone product quality.

Four, perfect after-sales service system. When we are looking for a Wuxi SMT patch factory, don't rush to inform the requirements. You can audit the factory first. Communicate with the business and engineering to determine the degree of cooperation between the PCBA processing plant staff. If there is no coordination within the factory, you don't want to think about how good the factory can be for delivery and after-sales. If you encounter no good coordination within the factory, and the internal buck-passing, it can only be you push each other, I push you, the delivery date is not routine, after-sales will make you collapse. Therefore, it is very important to choose a reliable supplier that can cooperate with you for a long time. The company can provide you with management and excellent executive force. Better price, better delivery; Excellent quality, products will speak; Quick feedback, worry-free after-sales.