ESD suppressor circuit
ESD suppressors are semiconductors that protect electronic components and systems from electrostatic discharge (ESD), the sudden and uncontrolled transfer of an electrical charge between conductors. They are installed near the protected line and connected in parallel with the signal line. Most products consist of diode arrays. ESD suppressors protect static-dissipative equipment from overvoltage transients by clamping voltages to levels which circuits can withstand. They shunt the majority of the ESD current away from the data line to a reference, usually the power rail and chassis ground. During production, transient voltage suppression (TVS) increases chip yields according to standards such as charged device model (CDM) and machine model (MM). During end-use, ESD suppressors protect electronic products such as cell phones, personal digital assistants (PDA), and computers according to test methodologies such as IEC 61000-4-2 from the International Electrotechnical Commission (IEC).
Specifications for ESD suppressors include peak pulse power, maximum reverse stand-off voltage, maximum clamping voltage, maximum peak pulse current, and maximum off-state capacitance. When there is a high degree of separation between the signal frequency and unwanted frequencies, low-capacitance ESD suppressors provide valuable filtering functions. With high-speed signals, however, higher-capacitance can filter out data and produce distortion. Consequently, low-capacitance ESD suppression systems may be better suited for high-speed data lines that use protocols such as universal serial bus (USB) 2.0, Gigabit Ethernet, and InfiniBand(R) (InfiniBand Trade Association).