View ssrp105b1 datasheet:

SSRP105B1 ® Application Specific Discretes DUAL ASYMMETRICAL OVERVOLTAGE ASD™ PROTECTION FOR TELECOM LINE MAIN APPLICATIONS Where asymmetrical protection against lightning strikes and other transient overvoltages is required : Solid-State relays SLIC with integrated ring generator DESCRIPTION The SSRP105B1 is a dual asymmetrical transient voltage suppressor designed to protect a solid-state ring relay or SLICs with integrated ring SO-8 generator from overvoltages. The asymmetrical protection configuration is necessary to allow the use of all different types of ringing schemes. FUNCTIONAL DIAGRAM FEATURES Dual bi-directional asymmetrical protection TIP 1 8 GND Stand-off voltages: Between Line and Ground NC 2 7 GND +105V for positive voltages -180V for negativ