Anti-static measures for instruments
(1) Connect an external resistor in series at each input of the MOS device.
(2) All different input leads of the MOS device cannot be left floating, and should be connected to the power ground, power (source) Vss or power (drain) VDD according to different circuits.
(3) The output of the CMOS device (except the analog switch) can be separated from the cable line by a resistor, and the circuit can be clamped to Vss or VDD with two high-speed switching diodes.
(4) When using long input cables, a filtering network should be used.
(5) At the input of electrostatic discharge (ESD) sensitive bipolar components, an RC network consisting of a resistor with a large resistance value and a capacitor with a capacity of not less than 100pF is connected externally to reduce the impact of electrostatic discharge (ESD). When the circuit characteristics are specified, two parallel diodes can also be used to clamp 0.5V voltage at each polarity to shunt the input to the ground.
(6) It is not allowed to connect the leads of ESD sensitive components installed on printed circuit boards directly to the terminals of electrical connectors without any protection circuit.
(7) The interface circuits of instruments and equipment should use ESD sensitivity level 3 or insensitive components as much as possible.
(8) External electrical connectors of instruments and equipment connected to ESD sensitive circuits should be equipped with ESD protection caps (covers).
(9) Keyboards, control panels, manual controls, switches and locking devices connected to ESD sensitive products should be designed to directly discharge the static charge on the human body through the chassis ground wire.
(10) Components and hybrid circuits should be arranged to keep ESD sensitive components away from components that generate electrostatic fields, such as exhaust fans, and electrostatic suppression technology and electrostatic shielding technology should be used when necessary.
(11) ESD sensitive products should be equipped with ground terminals connected to the earth or the metal shells of ships, spacecraft, rockets and missiles.
(12) If the chassis shell is overlapped, even if the overlap resistance is 0.1Ω, if the discharge current is 30A, there will be a 3V voltage at the overlap, that is, the reference potential of different circuits will differ by 3V. The solution is to use single-point grounding and avoid overlap as much as possible.