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Dual Port VDSL2 Line Driver

ISL1539A

The ISL1539A provides 4 internal wideband op amps

intended to be used as two pairs of differential line

drivers. The ISL1539A’s high bandwidth, 240MHz, and

demanding MTPR requirements of emerging VDSL2 line

driver designs. Less demanding requirements can be met

at very low quiescent powers using the supply current

adjustment features.

Each of the 4 internal op amps is a wideband current

feedback amplifier offering very high slew rate intrinsic to

that design using low quiescent current levels. Each of

the two pair of amplifiers (ports) can also be power

optimized to the application using two external quiescent

control logic pins. Full power is nominally 27.2mA/port

with options of medium power cutback to 23mA/port, a

low power condition at 13.5mA/port, and an off state at

<0.5mA/port. Added quiescent power flexibility is

gives the nominal currents listed above while inserting a

resistor from this pin to ground can be used to scale each

of the settings downward.

High power push/pull line driver applications as

illustrated in the example below are best supported using

a low headroom, high output current device. On ±12V

supplies, the ISL1539A offers a 1.1V headroom with

>360mA peak output current. Driving differentially this

High SFDR operation is also supported for supplies as low

as ±7.5V. Intended to be used as differential pairs, this

two port device includes special circuitry to minimize

common mode loop peaking while also reducing the

common mode output noise spectrum. That circuitry

links the two sides of each port, precluding their

application as individual amplifiers.

Features

• 360mA Output Drive Capability

• -65dBc MTPR (VDSL 8b Profile)

• High Slew Rate of 3000V/µs Differential

• Supply Current Control Pins

• Port Separation

- 78dB @ 500kHz

-70dB @ 1MHz

-60dB @ 4MHz

• Pb-Free (RoHS Compliant)

Applications*(see page 21)

• 8MHz and 17MHz VDSL2 Profiles

•ADSL2+

Related Literature (see Device Info page)

• AN1325 “Choosing and Using Bypass Capacitors”

• TB426 “Characterization of the Output Protection

Circuitry of the EL1528 DSL Driver for Lightning

Surges”

TABLE 1. ALTERNATE SOLUTIONS

PART #

(V)

BANDWIDTH

(MHz)

APPLICATIONS

ISL1557

±6

200

VDSL

ISL1534

±12

40

ADSL2+

ISL1536

±12

50

ADSL2+

Typical Application

4MHz Harmonic Distortion

Ro

Rb

Rf

+12V

+

-

SOURCE

Rb

Rf

+

-

Rg

-12V

3.2k

3.2k

711

¼

ISL1539A

¼

ISL1539A

Ro

LOAD

1:n

TYPICAL DIFFERENTIAL I/O LINE DRIVER

(1 OF 2 PORTS)

VO

VI

AV-DIFF = VO/VI = 10V/V

Ω

Ω

Ω

AV = +10

3rd HD

2nd HD

THD

September 23, 2009

FN6916.0