PCB Technical - What are the principles of PCB anti-interference design

The anti-interference problem is a very important link in modern PCB circuit design, which directly reflects the performance and reliability of the entire system. At present, the anti-jamming technologies used in the system mainly include hardware anti-jamming technology and software anti-jamming technology.

1) The design of hardware anti-jamming technology. The carrier signal of the inverter circuit of the flywheel energy storage system up to 20kHz determines that it will produce noise, so that the noise and harmonic problems generated by the power electronic devices in the system become the main interference, which will affect the equipment and nearby instruments The degree of influence is related to factors such as the anti-interference ability of its control system and equipment, wiring environment, installation distance and grounding method.

2) Software anti-interference technology

In addition to taking a series of anti-jamming measures on the hardware, measures such as digital filtering, setting software traps, and using watchdog program redundancy design to make the system run stably and reliably on the software. Especially, when the energy storage flywheel is in a certain working state for a long time, the state should be continuously detected in the main loop, and the corresponding operation should be repeated, which is also a method to enhance reliability.

The anti-interference design of the printed circuit board is closely related to the specific PCB design. Here is a collection of comprehensive and detailed PCB anti-interference design principles to share with you.

The specific principles are as follows:

1. The configuration of components

(1) Do not have too long parallel signal lines

(2) Ensure that the clock input terminals of the PCB clock generator, crystal oscillator and cpu are as close as possible, while keeping away from other low-frequency devices

(3) The components should be arranged around the core components, and the lead length should be minimized

(4) Partition layout of PCB board

(5) Consider the position and direction of the PCB board in the chassis

(6) Shorten the leads between high-frequency components

2. Configuration of decoupling capacitors

(1) Add a charge and discharge capacitor (10uf) for every 10 integrated circuits

(2) Leaded capacitors are used for low frequency, and chip capacitors are used for high frequency

(3) A 0.1uf ceramic capacitor should be arranged for each integrated chip

(4) The anti-noise ability is weak, and the devices with large power changes during shutdown should add high-frequency decoupling capacitors

(5) Do not share vias between capacitors

(6) Decoupling capacitor leads should not be too long

3. The design of the power cord

(1) Choose a suitable power supply

(2) Widen the power cord as much as possible

(3) Ensure that the power cord, bottom line direction and data transmission direction are consistent

(4) Use anti-interference components

(5) Add decoupling capacitor to the power inlet (10~100uf)

4. Design of the ground wire

(1) Separate analog ground and digital ground

(2) Try to use single point grounding

(3) Widen the ground wire as much as possible

(4) Connect the sensitive circuit to a stable ground reference source

(5) Partition design of PCB boards to separate high-bandwidth noise circuits from low-frequency circuits

(6) Minimize the area of the ground loop (the path formed by returning all components to the ground after the device is grounded is called "ground loop")