45. GDT for RS-485 Bus Lightning Protection

Rohit is designing an industrial control system where RS-485 communication runs through long outdoor cables (over 500 meters) between buildings. 

These long cable runs are highly vulnerable to lightning-induced surges. 

He needs a GDT at each RS-485 port entry as primary surge protection to absorb high-energy surges before they reach the RS-485 transceiver. 

Key requirements: 

• RS-485 bus operates in the range of −7V to +12V 

• GDT spark-over voltage: 75V (well above RS-485 voltage, fires only on surge) 

• Surge current: ≥5kA (8/20µs) for lightning-class protection 

• 2-pole GDT (A and B lines) 

• Through-hole package for robust mounting 

The company's AVL specifies Littelfuse, so the part must be selected from Littelfuse on DigiKey. 

Help him select a suitable GDT from Littelfuse on DigiKey.