The ISL1561 is a fixed gain dual port class-G differential

amplifier designed for driving full rate ADSL2+ and VDSL2

signals at very low power dissipation. The driver runs on a

single +14V power supply and internally generates higher

supply voltages when needed to enable power efficient

operation for high peak-to-average ratio (PAR) ADSL2+ and

VDSL2 signals.

In ADSL2+ mode of operation with full 19.8dBm transmit

signal power across 100Ω line load, each port consumes only

520mW of power, while with 19.5dBm VDSL2 8b profile a port

consumes 610mW of power. In VDSL2 17a mode of operation

with 14.5dBm transmit power, a port will consume 411mW of

power. These typical power consumption figures account for

receiver hybrid loading effects and transformer losses.

The ISL1561 provides two ports of wideband, current feedback

amplifiers optimized for low power consumption in xDSL

systems. The drivers achieve an average upstream missing

band power ratio (MBPR) distortion of better than -64dBc

under 19.8dBm transmit signal power into 100Ω load. A three

pin serial interface is used to program an 8-bit internal register

to set each port’s supply current with 0.5mA step size. This

flexibility allows the DSP to optimize each port separately

during modem training.

The device is supplied in a thermally-enhanced small footprint

(4mmx4mm) 24 lead QFN package. The ISL1561 is specified

for operation over the full -40°C to +85°C industrial

temperature range and is Pb-free RoHS compliant.

Features

• Internal fixed gain of 11.6V/V to transformer (see Figure 3)

• 360mA output drive capability

• 41.8VP-P differential output drive into 100Ω in class G mode

• VDSL2 8b profile MTPR of -64dBc

• VDSL2 17a profile MTPR of -60dBc

• ADSL2+, VDSL2 8b and 17a power consumption of 520mW,

610mW and 411mW respectively

• 8-bit programmable register to set supply current on each

port

• 3 pin serial port interface

Applications

• Dual port ADSL2+ and VDSL2 DSLAM