A high-voltage IC for a transformerless trunk and subscriber line interface

A new high-voltage, junction-isolated, complementary bipolar technology has been used to fabricate an IC for a transformerless trunk and subscriber line interface. The new technology provides both vertical p-n-p and n-p-n transistors with BV/SUB CE0/ greater than 60 V, betas of 100, and f/SUB T/´s of 200 MHz. It permits the straightforward op amp realization of a new op amp circuit configuration in transformerless line circuits. The new configuration uses the high-voltage IC plus some low voltage control circuitry to provide limited current battery-feed, loop-closure detection, reverse-battery signaling, two-wire to four-wire conversion, lightning protection, power-down capability, and longitudinal performance which is independent of the battery-feed current magnitude.