Talk about simple grounding method

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Talk about simple grounding method [Copy link]

Generally, in our AD system, there are very clear analog power/analog ground; digital power digital ground, these processing is relatively important. In the usual system == 1. We often use 10~20 ohm resistors to isolate analog power and digital power. As can be seen from the figure below, of course, using grouped isolated power is the best choice, but the cost is relatively high. 2. When dealing with analog ground and digital ground, the 1-point connection method is finally used. This connection point should be selected at the charge balance point on the PCB to prevent voltage difference. This requires a good foundation and experience in PCB and analog design. 3. Use LDO with high PSRR, and try to avoid using DCDC and power temperature and pressure devices with ripple exceeding 300UV. Of course, we can reduce interference from the power supply through differential input. 4. A good shielding cover can also reduce the impact of external electromagnetic radiation on the AD system, such as radar, mobile phone radiation, ultraviolet rays, etc. 1. First of all, we have to deal with the crystal interference problem of the system. The layout of the crystal on a PCB is more important. Of course, the selection is also very important. In theory, the lower the external crystal frequency in a system, the more stable the system is and the less susceptible it is to interference. However, internal frequency multiplication is basically a chip-level application level, and we need to worry about the compensation. If the crystal shell is metal, it is usually connected to the digital ground. Keep the crystal away from the ADC circuit as much as possible and close to the MCU 2. Between multiple power grounds, you can consider using inductors to connect them. Calculating a more suitable inductor and BYPASS capacitor can eliminate some interference signals attached to the power ground. These can be simulated using the famous PSPICE software. 3. When designing PCB, the line width of the power supply should be arranged according to the current size, usually several times that of ordinary signal lines. In battery-powered micro-power devices, it is recommended that the minimum power line width is not less than 15MIL (this is just our opinion). Of course, if conditions permit, you can use software to simulate the actual current size and the required line width, line thickness, etc. This can actually simulate the relevant parameters on the POWER PCB.