GE DS200PLIBG2A Contact DC module

The best protection from ESD damage is circuit inaccessibility. If all circuit components are positioned away from package seams, the static discharges can be prevented from reaching ESD sensitive components. There are two measures of "distance" to consider for inaccessibility: creepage and clearance. Creepage is the shortest distance between two points along the contours of a surface. Clearance is the shortest distance between two points through the air. An ESD hit generally arcs farther along a surface than it will when passing straight through the air. For example, a 20 kV discharge will arc about 10 mm (0.4 inches) through dry air, but the same discharge can travel over 20mm (0.8 inches) along a clean surface. Dirty surfaces can allow arcing over even longer creepage distances.

Designing Systems for ESD Immunity

ESD hardening includes the following techniques:

• Provide adequate creepage and clearance distances to prevent ESD hits from reaching sensitive circuitry; • Provide low impedance paths for ESD hits to ground; 

• Use diode clamps or transient voltage suppression devices for accessible, sensitive circuits

When ESD hits to circuitry cannot be avoided through creepage

 clearance and ground guarding techniques, i.e., at external connector pins, explicit clamping of the exposed lines is required to shunt the ESD current. Consult Standler9 for advice about ESD and transient protection for exposed circuit lines. In general, exposed lines require diode clamps to the power supply rails or zener clamps to chassis ground in order to shunt the ESD current to ground while clamping the voltage low enough to prevent circuit damage. The Neuron Chip’s I/O and control lines are connected directly to P1 without any ESD protection beyond that provided by the Neuron Chip itself. If these lines will be exposed to ESD in an application, protection must be added on the application electronics board. Figure 12 shows an example of the use of diode clamps to protect the control module I/O lines in a keypad scanning application.

 Company product range

----------------------Ruichang Mingsheng Automation Equipment Co., Ltd----------------------

PLC module, programmable controller, CPU module, IO module, DO module, AI module, DI module

Network communication module,

Ethernet module, motion control module, analog input module, analog output module, digital input module, digital output

Module, redundancy module, power module, relay output module, relay input module, processor module