Decoupling Capacitor Configuration

In the DC power supply loop, fluctuations in the load can generate power supply noise. This noise can be especially problematic in digital circuits where switching between states can cause sudden spikes in current, leading to transient noise voltage. To address this issue, decoupling capacitors are strategically configured on printed circuit boards to mitigate the impact of load changes. Here are the key principles for configuration:

• Connect a 10-100uF electrolytic capacitor across the power input. Consider using an electrolytic capacitor above 100uF if space permits for enhanced anti-interference effects.
• Install a 0.01uF ceramic capacitor for each integrated circuit chip. In cases of limited space, opt for a 1-10uF tantalum electrolytic capacitor for every 4-10 chips, offering low high-frequency impedance and minimal leakage current.
• For components sensitive to noise and experiencing significant current fluctuations during turn-off (e.g., ROM, RAM), directly link a decoupling capacitor between the power line (Vcc) and ground (GND) of the chip.
• Ensure the lead wires of decoupling capacitors are kept short, especially for high-frequency bypass capacitors.

The Size of Printed Circuit Board And The Layout of The Device

It is essential to maintain a moderate size for the printed circuit board. Excessively large boards can increase line length and impedance, compromising noise resistance and inflating costs. Conversely, overly small boards may struggle with heat dissipation and susceptibility to interference from neighboring lines.

When arranging devices, proximity matters. Devices that interact closely, such as logic circuits, should be positioned near each other to bolster anti-noise capabilities. Components like timers, crystal oscillators, and the CPU clock input, which are sensitive to noise, should be clustered together. To minimize noise interference, separate low-current and high-current circuits from logic circuits whenever possible. Employing separate circuit boards, if feasible, is highly recommended.

Experience has shown that a well-organized device layout can effectively reduce the temperature rise of printed circuits, resulting in significantly lower failure rates for devices and equipment.

The above guidelines highlight the importance of reliability design in PCB board design. These design considerations play a critical role in shaping the quality of the final circuit board and the overall performance of the product.

WellCircuits Limited: Your PCB Expert

WellCircuits Limited specializes in crafting high-precision double-sided, multi-layer, and impedance-controlled circuit boards, including blind buried vias and thick copper. Their offerings encompass a wide array of products, such as HDI, thick copper, backplanes, rigid-flex combinations, buried capacitors, buried resistors, Golden Fingers, and more, tailored to meet diverse customer requirements.