Intersil has introduced the ISL1539A, a new addition to its family of DSL line drivers for the VDSL2 high-bit rate Internet connectivity standard.
The device supports both the 8 and 17MHz VDSL2 profiles, and is compatible with the 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 demanding line interface designs and MTPR (multi-tone power ratio) targets.
The device 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 high slew rates at low quiescent supply current. Each of the two pairs of amplifiers (ports) includes two logic pins to step the quiescent current level in single designs supporting multiple DSL standards. An overall power adjustment pin provides low quiescent power in less demanding applications. Designers can select from medium power cutback to 23mA/port, a low power condition at 13.5mA/port, and an off state consuming less than 0.5mA/port.
With its wide 240MHz bandwidth and low distortion (less than -89dBc at 1 MHz, 2Vpp), the device can deliver greater than -67dBc MTPR into a 100Ohm 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 device offers 1.1V headroom with greater than 360mA peak linear output current.
Driving differentially in a VDSL2 application circuit, this equates to a 41.8V peak-to-peak swing into a 100Ohm differential load. The device also supports high SFDR (spurious-free dynamic range) operation from supplies as low as ±7.5V. Intended to be used as differential pairs, the two port device includes special circuitry to minimise common mode loop peaking while also reducing the common mode output noise spectrum. The device is available in compact 24 lead QFN packages.
