SIDACtor® Thyristor Negative Voltage Tracking SLIC Protector – B61089 Series

Littelfuse designed SIDACtor protection thyristors to protect different SLIC tip/ring pairs with independent voltage tracking for each pair. The B61089 series protects the SLIC interface against lightning-induced surge and power fault events. It contains fast switching crowbarring structures for negative events and a simple, fast switching diode structure for positive events. It is compatible with the basic levels of ITU K.20 and K.21. For compliance with the enhanced levels of ITU, TIA 968-B, or GR-1089, an additional series resistor in the tip and ring leads may be required. The SLIC chipset voltage reference may change as the on-hook/off-hook line condition changes. Therefore, this component is referenced to the -V_BAT so that its negative protection threshold follows this changing reference voltage level. This B61089 series utilizes a transistor gain network so that a low 5 mA current level will activate the thyristor-based portion of this protector component during negative events. This also allows an easier turn-on during slow rising power fault events. For all positive disturbances, the fast switching diode connected to earth reference will provide the needed protection.