How can industrial servos pass ESD electrostatic discharge testing?

The servo system must pass the ESD test according to the IEC 61000-4-2 standard (contact discharge ±4kV/±8kV, air discharge ±15kV). Audiotech's protection design includes:

1) Using ESD protection devices, such as ESD5V0D8B (SOT-23), on all human-machine interfaces (buttons, indicator lights, displays).

2) Connecting resistors (22-100Ω) in series and low-capacitance TVS, such as ESDLC5V0D3B, in parallel on the signal lines of all external interfaces (communication, encoders, I/O). For multi-channel interfaces, use array devices such as ESDSRV05-4H.

3) The metal chassis must be reliably grounded to provide a low-impedance discharge path for ESD current.

4) In PCB layout, interface devices should be placed close to the ports, and the traces from protection devices to the ports should be as short as possible.

5) In software, digital filtering and debouncing should be added to input signals that may be affected by interference.

During testing, each accessible point must be discharged multiple times with both positive and negative polarities. With the above design, the servo device can stably pass the ESD test without reset, damage or performance degradation.