Shenzhen HongYuan Electronics Co.,Ltd 
After analyzing the principle of the entire circuit, you can start to layout and route the entire circuit. Next, the editor of the smart audio circuit board will introduce the ideas and principles of the layout.
1. First of all, we will place the devices with structural requirements. When placing them, according to the imported structure, the connector must pay attention to the placement of pin 1.
2. Pay attention to the height limit requirements in the structure when laying out the smart audio circuit board.
3. If the layout is to be beautiful, it is generally positioned according to the coordinates of the outer frame or center line of the component (centered alignment).
4. The overall layout should consider heat dissipation.
5. When laying out the smart audio circuit board, it is necessary to consider the evaluation of the wiring channel and the space required for the equal length.
6. When laying out, it is necessary to consider the power flow direction and evaluate the power channel.
7. The high-speed, medium-speed and low-speed circuits should be separated.
8. Keep strong current, high voltage, and strong radiation components away from weak current, low voltage, and sensitive components.
9. Separate analog, digital, power supply and protection circuits.
10. The interface protection device should be placed as close to the interface as possible.
11. Requirements for the placement sequence of interface protection devices:
(1) The order of general power supply lightning protection components is: varistor, fuse, suppression diode, EMI filter, inductor or common mode inductor, and the sequential layout of any device above is missing in the schematic diagram;
(2) Generally, the order of protection devices for interface signals is: ESD (TVS tube), isolation transformer, common-mode inductor, capacitor, and resistor. For the lack of schematic diagram, the layout of any device above is extended; strictly follow the order of the schematic diagram (there must be The ability to judge whether the schematic diagram is correct) carry out "one-line" layout.
12. The level conversion chip (such as RS232) is placed close to the connector (such as a serial port).
13. Devices that are susceptible to ESD interference, such as NMOS and CMOS devices, should be kept away from areas that are susceptible to ESD interference (such as the edge area of a single board) as much as possible.
14. Clock device layout:
(1) Crystals, crystal oscillators and clock distributors should be as close as possible to related IC devices;
(2) The filter of the clock circuit (try to use "Π" type filter) should be close to the power input pin of the clock circuit;
(3) Whether the output of the crystal oscillator and the clock distributor is connected in series with a 22 ohm resistor;
(4) Whether the unused output pin of the clock distributor is grounded through a resistor;
(5) The layout of crystals, crystal oscillators and clock distributors should be kept away from high-power components, radiators and other heat-generating devices;
(6) Whether the distance between the crystal oscillator and the interface device is greater than 1inch.
15. Whether the switching power supply is far away from AD\DA converters, analog devices, sensitive devices, and clock devices.
16. The layout of the switching power supply should be compact, and the input and output should be separated. The layout should be strictly in accordance with the requirements of the schematic diagram, and the capacitors of the switching power supply should not be placed randomly.
17. Capacitors and filter devices:
(1) The capacitor must be placed close to the power pin, and the capacitor with the smaller capacitance should be closer to the power pin;
(2) The EMI filter should be close to the input port of the chip power supply: the filter capacitor in EMC protection;
(3) In principle, each power supply pin has a small capacitor of 0.1uf, and an integrated circuit has one or more large capacitors of 10uf, which can be increased or decreased according to specific conditions;
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