1. The resistance selection needs to meet the power derating at least 70%, and use a larger package on the premise that the power derating meets the requirements.
2. The ground network symbol in the schematic diagram needs to display the network name.
3. The capacitor selection needs to meet the rated voltage derating of ceramic capacitors by at least 70%, and the rated voltage of tantalum capacitors should be derated by at least 50%. 0603 package should be used on the premise of meeting the derating requirements.
4. The devices used need to comply with RoHS standards.
5. Priority is given to the 4-layer PCB for the laminated structure of the board. It is necessary to ensure 100±10Ω impedance matching for high-speed differential signals and 50±5Ω impedance matching for high-speed single-ended signals.
6. It is recommended to use high TG plate for the plate, and use the immersion gold process to make the through hole to make the plug hole and cover with palm oil, white silk screen.
7. The circuit board needs to be chamfered.
8. The design of positioning holes and mounting holes of the circuit board should be reasonable, and pay attention to metallized or non-metallized holes;
9. Lead-free soldering process is required for circuit board soldering.
10. The fixed pins of connectors such as Micro USB need to be plugged in to ensure reliability.
11. SD, USB and other communication data lines need ESD protection, and TVS is recommended.
12. The power pin accessory of the USB host controller interface needs to place an energy storage capacitor with a capacitance value of 10uF, and several small decoupling capacitors in parallel.
13. No series resistance is required on the USB signal link.
14. The button circuit is best to be used for hardware debounce and ESD protection, and TVS is recommended;
15. The interface for external power supply requires an energy storage capacitor to be placed at the power supply pin.
16. ESD protection is required for external interfaces, and TVS (such as SL05T1G) is recommended.
17. The signal link needs to be connected in series with a current-limiting resistor with a resistance value of 100~200Ω.
18. It is best to control the power supply network of each module separately, and it is better to power on separately according to the sequence when power on and reset;
19. The ESD device is placed on the same layer of the protected signal and close to the signal entrance;
20. The analog signal ground and digital signal ground should be separated and isolated, and magnetic beads are recommended.
