Intersil's ISL1539A provides dual port, high performance VDSL2 line drivers for DSLAM designs

The ISL1539A supports both the 8MHz and 17MHz VDSL2 profiles, and is compatible with the widely used ADSL2+ standard. It provides a low-power solution in a space-efficient package to enable densely packed 24-port and 48-port deployments. It features 240MHz bandwidth and greater than 3000V/usec differential slew rate, ensuring adequate design margins for the most demanding line interface designs and multitone power ratio (MTPR) targets.

The ISL1539A includes four internal wideband op amps that are configured as two pairs of differential line drivers. Each driver is a wideband current feedback amplifier providing very high slew rates at low quiescent supply current. Each of the two pairs of amplifiers (ports) also includes two logic pins to step the quiescent current level in single designs supporting multiple DSL standards. In addition, an overall power adjustment pin provides very low quiescent power in less demanding applications. Full power is nominally 27.2mA/port. Designers can select from medium power cutback to 23mA/port, a low power condition at 13.5mA/port, and an off state consuming <0.5mA/port.

With its wide 240MHz bandwidth and low distortion (< -89dBc at 1 MHz, 2Vpp), the ISL1539A can deliver > -67dBc MTPR into a 100 ohm line load for the VDSL2 8b profile. The output stage uses a low headroom, high peak current design that can support high power push/pull line driver applications. On ±12V supplies, the ISL1539A offers 1.1V headroom with >360mA peak linear output current. Driving differentially in a VDSL2 application circuit, this equates to a 41.8 V peak-to-peak swing into a 100-ohm differential load. The device also supports high spurious-free dynamic range (SFDR) operation from supplies as low as ±7.5V. Intended to be used as differential pairs, the two-port ISL1539A includes special circuitry to minimize common mode loop peaking while also reducing the common mode output noise spectrum.