1. Signal "ground"; signal "ground" is also known as reference "ground", is the reference point of zero potential, and also a public segment constituting circuit signal circuit, graphic symbol "⊥". 1) DC: DC "ground", zero potential reference point. 2) Communicate: AC's zero line. It should be distinguished from the ground wire. 3) Power: the zero potential reference point of the large current network device and the amplifier device. 4) Simulate the zero potential reference point of the amplifier, sampling holder, A / D converter, and comparator. 5) Digitally: Also called logically, is the zero potential reference point of the digital circuit. 6) "Heat": The switching power supply does not need to use a transformer, the "ground" of its switching circuit is related to the city power grid, and the so-called "hot", it is charged, the graphic symbol is: "". 7) "Cold": Since the high-frequency transformer of the switching power supply is isolated, the output is isolated; but since the feedback circuit is often used, it can transmit the feedback signal and "ground" from both parties; so the output side For "cold, it" does not charge. The graphic symbol is "⊥".
2. Protect "land"; protecting "land" is a wiring method set in order to protect personnel. Protect the "land" line to connect the electrical appliance, and the other end is reliably connected to the earth. 3. "Land" in the sound. 1) Shielding line grounding: The sound system is to prevent interference, and the metal casing is connected to the signal "ground" by the wire, which is called the shield. 2) Audio dedicated "land": professional audio in order to prevent interference, in addition to shielding "land", it is necessary to connect with audio "ground". This grounding device should be embedded, and should be connected to the respective grounding end of the isolation transformer and the shielded regulator power source as a dedicated audio connection place in the sound control chamber.
Different ground processing methods. 1. Digitally and simulate should be separated; in high requirements circuitry, digitally and simulation must be separated. Even in two "ground" on the same chip on the same chip on the A / D, D / A converter, it is only connected to the system only. " 2. Floating and grounding; system floating, floating the ground wires of the system circuits, not connected to the earth. This approach has a certain anti-interference ability. However, the insulation resistance of the system and land cannot be less than 50mΩ. Once the insulation performance is lowered, it will cause interference. Usually, the system is floating, the case is grounded, and the anti-interference ability can be enhanced and safe and reliable. 3. Little ground; in the low frequency circuit, there is no significant impact between the wiring and components. The usual frequency is less than 1 MHz, which is grounded. 4. Multi-ground. In the high frequency circuit, the influence of parasitic capacitance and inductance is large. Usually the frequency greater than 10MHz, using multi-point grounding
