How to Connect the Chassis to the Circuit Board Ground?
The chassis is made of metal, and there is a screw hole in the middle, which connects to the ground. Here, a 1M resistor is connected in parallel with a 0.1uF capacitor to connect to the circuit board ground. What are the benefits of this?1. If the chassis ground is unstable or has static electricity, directly connecting it to the circuit board ground can damage the circuit board chips. By adding a capacitor, low-frequency high voltage and static electricity can be isolated, protecting the circuit board. The high-frequency interference from the circuit will be directly connected to the chassis through the capacitor, serving the function of isolating direct current from alternating current.2. Why add a 1M resistor? This is because, without this resistor, when there is static electricity on the circuit board, the 0.1uF capacitor connected to the ground will interrupt the connection to the chassis ground, effectively leaving it floating. If these charges accumulate to a certain extent, problems will arise; it must be connected to the ground. Thus, the resistor is used for discharging.3. A 1M resistor is quite large, and if there is static electricity or high voltage from the outside, it can effectively reduce the current and prevent damage to the chips inside the circuit.
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