SMT plasma arrester features low, stable capacitance
By Bill Schweber -- EDN, September 8, 2005
Targeting use as surge protection for broadband circuits, a trio of Greentube gas-plasma arresters (similar to gas discharge tubes) from Littelfuse has maximum capacitance of just 1.5 pF along with low insertion loss, and these values remain constant over a range of voltages and temperatures, a critical factor for gigahertz-range suitability The SL0902 devices, with a 5×5-mm footprint, are available in 90, 230, and 350V versions. The protectors generally work in conjunction with a fuse to provide both surge and fusing protection in applications such as telephone-company and DSL lines, satellite boxes, and CATV interfaces. Their impulse discharge-current rating, per industry-standard test conditions, shows that they can divert a 2.5-kA pulse without destruction.
The 90V version has a dc break-over rating of 72 to 108V at 2 kV/sec with a maximum break-over voltage of 400V at 100 V/μsec and 600V at 1 kV/μsec. The 230 and 350V units have dc break-over ratings of 184 to 276 V and 400 to 500 V, respectively; maximum break-over voltages differ somewhat. All models have an ac discharge current of 2.5 A. The SL0902 devices sell for less than 20 cents (OEM quantities).
Littelfuse Inc, www.littelfuse.com.
