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Anti-interference Design Principles

1) power cord Design

1. select an appropriate power supply

2. Try to widen the power cord

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

4. Use anti-interference components (magnetic beads, Power Filter)

5. Add the decoupling capacitor to the power entry

2) Ground Design

1. Separated analog and digital

2. Try to use single point of Ground Connection

3. Try to widen the ground line

4. Connect the sensitive circuit to a stable grounding reference source

5. Partition the PCB and separate the high-bandwidth noise circuit from the low-frequency circuit.

6. Minimize the area of the grounding loop

3) components

1. Do not have long Parallel Signal Lines

2. Ensure that the PCB clock generator, crystal oscillator and CPU clock end are as close as possible, while away from other low-frequency devices

3. components should be configured around the core period to minimize lead Length

4. Partition layout of PCB 5. Partition layout of PCB

5. Consider the position and direction of the PCB in the chassis.

6. Shorten the lead between high-frequency components

4) decoupling capacitor Configuration

1. Each 10 ic must contain a charge/discharge capacitor.

2. The lead capacitor is used for Low Frequency patch capacitors for high frequency

3. Each integrated chip needs to have a 0.1uf capacitor.

4. High-frequency Decoupling capacitor must be applied to devices with weak noise and great changes in power supply upon shutdown.

5. Do not share holes between Capacitors

6. the decoupling capacitor lead cannot be too long.

5) Principles of noise reduction and electromagnetic interference reduction

1. Use a 45-degree line instead of a 90-degree line

2. The series resistance method is used to reduce the hop speed change rate of the circuit signal edge.

3. The shell of the Z crystal oscillator must be grounded

4. Do not leave unused door circuits Blank

5. Little interference between the clock line and the I/O Line

6. Try to make the EMR around the clock line 0

7. Io drive circuit should be close to the PCB edge whenever possible

8. Do not form a loop for any signal

9. The distribution inductance of high-frequency boards and capacitors cannot be ignored.

10. The power line and AC line are usually arranged on boards different from the signal line.

 

Ad basic knowledge 2