How to Select and Layout Power Components?

Power PCB Component Layout
In the power supply PCB design process, from the electromagnetic compatibility (EMC) point of view, you need to focus on the following three main factors:

1、Input/output parameters: input voltage, current, frequency and other parameters will affect the selection and layout of components.


2、Device density: high-density device layout requires reasonable planning of component spacing and alignment to avoid electromagnetic interference.


3、Power consumption: The layout of high power consumption components needs to consider heat dissipation to avoid local overheating.


A practical rule is that the area occupied by surface mount components should be no more than 20% of the substrate, and the power dissipation per square inch should be no more than 2W.


In terms of component layout, the following principles should be followed:

1、Functional partitioning: Place digital circuits, analogue circuits and power supply circuits separately to reduce mutual interference.


2、Frequency isolation: Separate high-frequency circuits from low-frequency circuits to avoid interference of high-frequency signals with low-frequency circuits.


3、Sensitive component protection: Keep noise-prone components, small-current circuits, and high-current circuits away from logic circuits to protect sensitive components.


4、Interference source control: the clock circuit and high-frequency circuits and other major sources of interference and radiation should be arranged separately, away from sensitive circuits.


5、Input and output location: Input and output chips should be located close to the I/O exit of the hybrid IC package.


Power PCB board2


High-frequency component layout.

1、Shorten the connecting lines to reduce the distribution parameters and mutual electromagnetic interference.


2、Maintain distance between components susceptible to interference.


3、Inputs and outputs are far away from interference sources.


4、Oscillator close to the use of the clock chip position, away from the signal interface and low-level signal chip.


5、Components are arranged in parallel and parallel or perpendicular to one side of the substrate to reduce the distribution parameters between components.


6、The lead-in pads for power and ground should be arranged symmetrically, preferably evenly distributed.


7、The mounting area of the bare chip is connected to the most negative potential plane.


Multi-layer hybrid IC layer arrangement.

1、Power and ground layer allocation: power and ground layer is allocated in the inner layer, play the role of shielding layer, inhibit common mode RF interference inherent in the circuit board, reduce the distribution of high-frequency power impedance.


2、Power and ground layer adjacent: power supply plane and ground plane as close as possible to each other, generally ground plane in the power plane above, using interlayer capacitance as a power supply smoothing capacitance, while the ground plane on the power plane distribution of radiation current to play a shielding role.


3、Wiring layer arrangement: the wiring layer should be arranged as far as possible with the power supply or ground plane adjacent to produce flux cancellation effect.


Process and component selection
Hybrid integrated circuits have three manufacturing processes to choose from:

1、Single-layer thin-film process: suitable for high-speed, high-frequency and high packaging density of the circuit, but can only do a single layer of wiring and higher costs.


2、Multi-layer thick film process: lower cost of manufacturing multi-layer interconnect circuits, can reduce the board’s electromagnetic radiation and improve interference immunity.


3、Multi-layer co-fired thick film process: has a higher assembly density and better high frequency characteristics, is currently the mainstream technology of passive integration.


Power PCB board1


Component selection

1、Active components: try to use the bare chip, no bare chip can be used when the corresponding encapsulated chip.


2、 Surface-mounted chip: In order to get the best EMC characteristics, try to use the surface-mounted chip.


3、Clock frequency: In order to meet the technical specifications of the product under the premise, try to choose a low-speed clock, for example, in the HC can be used by no means use the AC, CMOS4000 can work without HC.


4、Capacitor selection: capacitors should have a low equivalent series resistance, to avoid large attenuation of the signal.



Power supply PCB design is a complex project that requires comprehensive consideration of a variety of factors, such as component layout, process selection, component selection and so on. Following the above principles and recommendations will help design a more reliable and stable power supply system and improve the overall performance and life of electronic products.

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