General Description
The Supertex HT0638 is an integrated electronic line switch controllable from four logic-level inputs. These devices are intended as a replacement for mechanical hook switches and relays in telephones, answering machines, and similar telecommunications equipment. They switch the positive (Tip) side of the telephone line using control inputs that are referenced to the negative (Ring) side of the line. In the off state, it can hold-off 375 volts. In the on state, the series resistance is 15Ω maximum.

Features
❑ 15Ω maximum switch resistance
❑ Current limiting protection
❑ 4 logic control inputs
❑ Operates at 2V input
❑ 2µA maximum quiescent current at 100V

Applications
❑ Telephone handsets
❑ Fax machines
❑ Answering machines
❑ Auto-dial alarm systems