How should the DCDC on the board be laid out?

wangerxian

How should the DCDC on the board be laid out? [Copy link]

In PCB design, the design of the power supply part is a more difficult and more important part. Generally, power chip manufacturers will recommend some layouts. The power supply layout principles I know are these three points: separation of analog and digital power supplies , separation of high-power power supplies and low-power power supplies , and the proximity principle of power supply layout .

1. Separation of analog and digital power supplies. This should be easy to understand. Analog circuits and digital circuits should be laid out separately during design. Digital circuits generally contain high-frequency parts. Their frequency components and bandwidth are usually larger, and the corresponding noise components are also more complex. The operating frequency of analog circuits is usually not very high, and the frequency components are relatively less. Therefore, when the noise components of digital circuits are mixed into analog circuits, glitches, interference and other problems may occur. Therefore, their power supply circuits must also be divided into zones.

Second, high-power power supplies should be separated from low-power power supplies. Some circuits may have high-power components and low-power components, and the power supply capabilities they require are very different. High-power components usually generate heat, such as the heating wire of a kettle. These heating components will radiate heat to surrounding devices and affect the working state of low-power devices. Therefore, under normal circumstances, this is generally done by adding a new insulation layer or designing the power device independently, and separating it from the other components in layout. Naturally, this also involves the separation of the layout of the power supply part.

3. The proximity principle of power supply layout. Let me explain this. For example, my circuit design includes 5 power supply voltages: 3.3V, 5V, 12V, 24V, and 220VAC. In order to simply describe my idea, we will temporarily define the four DC power supplies as being generated by 220VAC, that is to say, 3.3V, 5V, 12V, and 24V are all generated by 220VAC. There are many ways to generate them. The simplest is to use an AC/DC module to directly convert the required DC voltage. All power supplies are from the same source, and the separated voltages are used to power the microcontroller (3.3V), analog circuit (5V), control part (12V), and heating part (24V). It is not difficult to understand that each power supply must be as close to its own "sphere of influence" as possible. This is the proximity of the power supply layout. The reason for doing this is to minimize source impedance and reduce the chance of power supply interference.

You can share the design points or techniques of PCB power supply, or share any problems you encounter in PCB power supply design, and have fun together ~

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