ISL5571A High Voltage Switch
The ISL5571A replaces electromechanical relays on subscriber line cards. It contains two line‑break MOSFET switches, a ring‑return MOSFET, and a ring‑access SCR, all controlled by TTL logic levels (0.8 V low, 2.4‑5 V high). The device offers low on‑resistance, high blocking voltage, and integrated current‑limiting, thermal shutdown, and over‑voltage protection.
Typical applications include central office, PBX, and DLC line interface circuits. The datasheet provides pin descriptions, absolute maximum ratings, electrical specifications, truth tables, and design guidelines for external protection and break‑before‑make operation.
| Line‑Break Switch Blocking Voltage | >330 V |
|---|---|
| DC Current Limit (25 °C) | 125 mA |
| Logic Input Low Voltage | ≤0.8 V |
External protection must limit the TLINE terminal to a maximum of 130 V to avoid exceeding the device’s voltage rating.