1

Fixed Gain Dual Port Class-G Differential xDSL Line

Driver

ISL1561

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 100

Ω 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 100

Ω 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

• 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

Alternate Part

• ISL1591 Class AB VDSL Driver

FIGURE 1. BLOCK DIAGRAM

FIGURE 2. CLASS G+ vs CLASS AB DRIVER TOTAL POWER

CLASS

AB

DRIVER

POWER MANAGEMENT

+14V

ANALOG

INPUT

BIAS

CURRENT

SETTING

SWITCH SIGNAL

BOTH PORTS

SERIAL

INTERFACE

AFE

OUTPUT OF

DRIVER

SUPPLY

RAILS OF

LINE DRIVERS

SCLK

SDATA

BOOST

INP

OUT

CPP

CPSW

CMSW

CMM

CS

1 OF 2

PORTS

0

100

200

300

400

500

600

700

800

900

2

4

6

8

10

12

14

16

18

20

Tx POWER (dBm)

8b CLASS AB

17a CLASS AB

8b CLASS G

17a CLASS G

CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.

1-888-INTERSIL or 1-888-468-3774

Intersil (and design) is a trademark owned by Intersil Corporation or one of its subsidiaries.

All other trademarks mentioned are the property of their respective owners.

February 26, 2013

FN7941.1