Handling Sensitive Circuits on a PCB
- Power Cord: When designing the power line for a printed circuit board, it is crucial to consider the current and increase the width of the power line to reduce loop resistance. Pay attention to the orientation of the power supply and ground wire, ensuring it is opposite to the direction of data and signal transmission. This helps improve anti-noise capabilities and should flow from the final stage to the front stage.
- Ground Design: The key principle of ground design is to separate digital and analog circuits whenever possible. If the circuit board contains both logical and linear circuits, they should be isolated. Low-frequency circuits should utilize single-point parallel grounding when feasible, while high-frequency circuits should employ multi-point serial grounding. Ground wires should be thickened to handle the current on the printed board effectively.
Interference Elements on the PCB
Interference on a PCB can originate from various sources such as lightning, relays, silicon-controlled devices, motors, and high-frequency clocks. Interference can propagate through conduction along wires or through radiation in space. Sensitive components that are susceptible to interference include A/D and D/A converters, single-chip microcomputers, digital ICs, and weak signal amplifiers.
Types of Interference
Interference on a PCB can be categorized into radiation and conduction. Radiation interference leverages space as a medium to disrupt signals, whereas conductive interference exploits a conductive medium as a pathway.
Managing Sensitive Components on a PCB
- When arranging components on a PCB, consider factors such as production and maintenance convenience. Ensure capacitors are of the same polarity and position heat-generating components away from sensitive ones. For moisture-sensitive components packaged in a tape-and-reel system, meticulously control the exposure time to prevent moisture-related damage.
