Analog Devices AD8391 Service Manual

xDSL Line Driver

a

FEATURES
Ideal xDSL Line Driver for VoDSL or Low Power

Applications such as USB, PCMCIA, or PCI Based
Customer Premise Equipment (CPE)

High Output Voltage and Current Drive

340 mA Output Drive Current

Low Power Operation

3 V to 12 V Power Supply Range
1-Pin Logic Controlled Standby, Shutdown
Low Supply Current of 19 mA (Typical)

Low Distortion

–82 dBc SFDR, 12 V p-p into Differential 21  @ 100 kHz

4.5 nV/√Hz Input Voltage Noise Density, 100 kHz

Out-of-Band SFDR = –72 dBc, 144 kHz to 500 kHz,

= 100 , P

Z

LINE

High Speed

40 MHz Bandwidth (–3 dB)
375 V/s Slew Rate

APPLICATIONS
VoDSL Modems
xDSL USB, PCI, PCMCIA Cards
Line Powered or Battery Backup xDSL Modems

= 13.5 dBm

LINE

3V to 12 V with Power-Down

AD8391

PIN CONFIGURATION

8-Lead SOIC

(Thermal Coastline)

V

MID

IN1

PWDN

+V

V

OUT

V

1

2

 

3

S

4

1

S

AD8391

V

 

8

IN2

S

V

7

MID

6

–V

S

5

V

2

OUT

PRODUCT DESCRIPTION

The AD8391 consists of two parallel, low cost xDSL line drive
amplifiers capable of driving low distortion signals while running on
both 3 V to 12 V single-supply or equivalent dual-supply rails. It is
primarily intended for use in single-supply xDSL systems where low
power is essential, such as line powered and battery backup systems.
Each amplifier output drives more than 250 mA of current while
maintaining –82 dBc of SFDR at 100 kHz on 12 V, outstanding
performance for any xDSL CPE application.

The AD8391 provides a flexible power-down feature consisting of
a 1-pin digital control line. This allows biasing of the AD8391 to
full power (Logic 1), standby (Logic three-state maintains low
amplifier output impedance), and shutdown (Logic 0 places
amplifier outputs in a high impedance state). PWDN is refer­enced to –V

.

S

Fabricated on ADI’s high speed XFCB process, the high bandwidth
and fast slew rate of the AD8391 keep distortion to a minimum,
while dissipating a minimum of power. The quiescent current of the
AD8391 is low: 19 mA total static current draw. The AD8391
comes in a compact 8-lead SOIC “thermal coastline” package and
operates over the temperature range –40°C to +85°C.

REV. A

UPSTREAM POWER – 10dB/DIV

EMPTY BIN

25 250137.5

FREQUENCY – kHz

Figure 1. Upstream Transit Spectrum with Empty Bin
at 45 kHz; Line Power = 12.5 dBm into 100

Ω

Information furnished by Analog Devices is believed to be accurate and
reliable. However, no responsibility is assumed by Analog Devices for its
use, nor for any infringements of patents or other rights of third parties that
may result from its use. No license is granted by implication or otherwise
under any patent or patent rights of Analog Devices. Trademarks and
registered trademarks are the property of their respective owners.

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: [phone] www.analog.com
Fax: [phone] © 2003 Analog Devices, Inc. All rights reserved.

AD8391–SPECIFICATIONS

(@ 25C, VS= 12 V, RL = 10 , V
unless otherwise noted. See TPC 1 for Basic Circuit Configuration.)

= VS/2, G = –2, RF= 909 , RG= 453 ,

MID

Parameter Conditions Min Typ Max Unit

DYNAMIC PERFORMANCE

–3 dB Bandwidth G = –1, V

G = –2, V

0.1 dB Bandwidth V
Large Signal Bandwidth V
Slew Rate V
Rise and Fall Time V

< 0.4 V p-p 4 MHz

OUT

= 4 V p-p 50 MHz

OUT

= 4 V p-p 375 V/µs

OUT

= 4 V p-p 8 ns

OUT

Settling Time 0.1%, V

< 0.4 V p-p, RG = 909 Ω 40 MHz

OUT

< 0.4 V p-p 38 MHz

OUT

= 2 V p-p 60 ns

OUT

NOISE/HARMONIC
PERFORMANCE

Distortion, G = –5 (RG = 178 Ω)V

Second Harmonic 100 kHz, R

= 8 V p-p (Differential)

OUT

= 21 Ω –82 dBc

L

Third Harmonic 100 kHz, RL = 21 Ω –95 dBc
MTPR (In-Band) 25 kHz to 138 kHz, R
SFDR (Out-of-Band) 144 kHz to 500 kHz, R

= 21 Ω –70 dBc

L

= 21 Ω –72 dBc

L

Input Noise Voltage f = 100 kHz Differential 4.5 nV/√Hz
Input Noise Current f = 100 kHz 9 pA/√Hz
Crosstalk f = 1 MHz, G = –2, Output to Output 64 dB

DC PERFORMANCE

Input Offset Voltage V

= +VS/2 ±2 ±15 mV

MID

to T

T
V

MIN

MID

MAX

= Float ±2mV

±3mV

Input Offset Voltage Match ±0.25 ±2.6 mV

T

Transimpedance ∆V

to T

MIN

MAX

= 5 V 10 MΩ

OUT

±0.35 mV

INPUT CHARACTERISTICS

Input Resistance 125 Ω
Input Bias Current In1, In2 pins 2.5 10 µA
Input Bias Current Match In1 – In2 ±0.5 ±6 µA
CMRR V

= VIN = 5.5 V to 6.5 V, ∆V

MID

/∆VIN, cm 48 dB

OS

Input CM Voltage Range 1.2 to 10.8 V

Accuracy V

V

MID

Input Resistance 2.5 kΩ

V

MID

V

Input Capacitance 10 pF

MID

= Float Delta from +VS/2 ±5 ±30 mV

MID

OUTPUT CHARACTERISTICS

Output Resistance Frequency = 100 kHz, PWDN 1 0.3 Ω
Output Resistance Frequency = 100 kHz, PWDN 0 3 kΩ
Output Voltage Swing R
Linear Output Current SFDR < –75 dBc, f = 100 kHz, R

= 100 Ω 0.1 11.9 V

LOAD

= 21 Ω 340 mA

L

Short-Circuit Current 1500 mA

POWER SUPPLY

Supply Current PWDN = 1 16 19 21 mA

T

MIN

to T

MAX

22 mA
STBY Supply Current PWDN = Open or Three-State 10 mA
SHUTDOWN Supply Current PWDN = 0 4 6 mA
Operating Range Single Supply 3.0 12 V
Power Supply Rejection Ratio V

= VS /2, ∆VS = ± 0.5 V 55 dB

MID

LOGIC INPUT (PWDN)

Logic 1 Voltage –VS + 2.0 V
Logic 0 Voltage –V

+ 0.8 V

S

Logic Input Bias Current ± 300 µA
Turn-On Time RL = 21 Ω, IS = 90% of Typical 200 ns

Specifications subject to change without notice.

–2–

REV. A

AD8391

SPECIFICATIONS

(@ 25C, VS=3 V, RL = 10 , V
See TPC 1 for Basic Circuit Configuration.)

= VS/2, G = –2, RF= 909 , RG= 453 , unless otherwise noted.

MID

Parameter Conditions Min Typ Max Unit

DYNAMIC PERFORMANCE

–3 dB Bandwidth G = –1, V

G = –2, V

0.1 dB Bandwidth V
Large Signal Bandwidth V
Slew Rate V

< 0.4 V p-p 3.5 MHz

OUT

= 2 V p-p 30 MHz

OUT

=2V p-p 50 V/µs

OUT

Rise and Fall Time Differential, V
Settling Time 0.1%, V

< 0.4 V p-p 37 MHz

OUT

< 0.4 V p-p 36 MHz

OUT

= 1 V p-p 15 ns

OUT

= 2 V p-p 110 ns

OUT

NOISE/HARMONIC
PERFORMANCE

Distortion V

= 4 V p-p (Differential)

OUT

Second Harmonic 100 kHz, RL= 21 Ω –81 dBc
Third Harmonic 100 kHz, R

= 21 Ω –97 dBc

L

Input Noise Voltage f = 100 kHz Differential 4.5 nV/√Hz
Input Noise Current f = 100 kHz 9 pA/√Hz

DC PERFORMANCE

Input Offset Voltage V

= +VS/2 ±3 ±15 mV

MID

to T

T
V

MIN

MID

MAX

= Float ±3mV

±4mV

Input Offset Voltage Match ± 0.1 ±2.6 mV

T

Transimpedance ∆V

to T

MIN

MAX

= 1 V 8 MΩ

OUT

±0.2 mV

INPUT CHARACTERISTICS

Input Resistance 125 Ω
Input Bias Current In1, In2 pins 1 7 µA
Input Bias Current Match In1 – In2 ±0.5 ±4 µA
CMRR V

VIN= 1.3 V to 1.5 V, ∆VOS /∆VIN, cm

MID

48 dB

=

Input CM Voltage Range 1.2 to 2.1 V

Accuracy V

V

MID

Input Resistance 2.5 kΩ

V

MID

V

Input Capacitance 10 pF

MID

= Float, Delta from +VS/2 ±5 ±30 mV

MID

OUTPUT CHARACTERISTICS

Output Resistance Frequency = 100 kHz, PWDN 1 0.2 Ω
Output Resistance Frequency = 100 kHz, PWDN 0 9 kΩ
Output Voltage Swing R
Linear Output Current SFDR < –82 dBc, f = 100 kHz, R

= 100 Ω 0.1 2.9 V

L

= 21 Ω 125 mA

L

Short-Circuit Current 1000 mA

POWER SUPPLY

Supply Current PWDN = 1 13 16 18 mA

T

MIN

to T

MAX

19 mA
STBY Supply Current PWDN = Open or Three-State 8 mA
SHUTDOWN Supply Current PWDN = 0 1 2 mA
Operating Range Single Supply 3.0 12 V
Power Supply Rejection Ratio V

= VS/2, ∆VS = ±0.5 V 55 dB

MID

LOGIC INPUTS (PWDN [1,0])

Logic 1 Voltage –VS + 2.0 V
Logic 0 Voltage –V

+ 0.8 V

S

Logic Input Bias Current ± 60 µA
Turn-On Time RL = 21 Ω, IS = 90% of Typical 200 ns

Specifications subject to change without notice.

REV. A

–3–

AD8391

ABSOLUTE MAXIMUM RATINGS

Supply Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.6 V

Internal Power Dissipation

2

1

Small Outline Package (R) . . . . . . . . . . . . . . . . . . . 650 mW

Input Voltage (Common-Mode) . . . . . . . . . . . . . . . . . . . . ± V

Logic Voltage, PWDN . . . . . . . . . . . . . . . . . . . . . . . . . . . . ±V

S

S

Output Short-Circuit Duration

. . . . . . . . . . . . . . . . . . . . .Observe Power Derating Curve

Storage Temperature Range . . . . . . . . . . . . –65°C to +150°C

Operating Temperature Range . . . . . . . . . . . –40°C to +85°C

Lead Temperature Range (Soldering 10 sec) . . . . . . . . . 300°C

NOTES

1

Stresses above those listed under Absolute Maximum Ratings may cause perma­nent damage to the device. This is a stress rating only; functional operation of the
device at these or any other conditions above those indicated in the operational
section of this specification is not implied. Exposure to absolute maximum rating
conditions for extended periods may affect device reliability.

2

Specification is for device on a 4-layer board in free air at 85°C: 8-Lead SOIC
package: ␪JA = 100°C/W.

MAXIMUM POWER DISSIPATION

The maximum power that can be safely dissipated by the
AD8391 is limited by the associated rise in junction temperature.
The maximum safe junction temperature for a plastic encapsu­lated device is determined by the glass transition temperature of
the plastic, approximately 150°C. Temporarily exceeding this
limit may cause a shift in parametric performance due to a change
in the stresses exerted on the die by the package.

To ensure proper operation, it is necessary to observe the maxi­mum power derating curve.

2.0

1.5

8-LEAD SOIC PACKAGE

1.0

0.5

MAXIMUM POWER DISSIPATION – W

0

–50

–40 –30 –20 –10 0 10 20 30 40 50 60 70 80 90

AMBIENT TEMPERATURE – C

TJ = 150C

Figure 2. Plot of Maximum Power Dissipation
vs. Temperature

ORDERING GUIDE

Temperature Package Package

Model Range Description Option

AD8391AR –40°C to +85°C 8-Lead SOIC R-8
AD8391AR–REEL –40°C to +85°C 8-Lead SOIC R-8
AD8391AR–REEL7 –40°C to +85°C 8-Lead SOIC R-8
AD8391AR–EVAL Evaluation Board

CAUTION

ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily
accumulate on the human body and test equipment and can discharge without detection. Although
the AD8391 features proprietary ESD protection circuitry, permanent damage may occur on
devices subjected to high energy electrostatic discharges. Therefore, proper ESD precautions are
recommended to avoid performance degradation or loss of functionality.

–4–

REV. A

Typical Performance Characteristics–AD8391

TIME – ns

0.3

OUTPUT VOLTAGE – V

0.2

0.1

0

–0.1

–0.2

–0.4

1007550250 125 150 175 200 225 250

–0.3

0.4
VS = 1.5V

G

= –2

R

L

= 10

CF = 3pF

CF = 0pF

TIME – ns

1.5

OUTPUT VOLTAGE – V

1.0

0.5

0

–0.5

–1.0

–2.0

1007550250 125 150 175 200 225 250

–1.5

2.0

VS = 1.5V

G

= –2

R

L

= 10

CF = 3pF

CF = 0pF

TIME – ns

0.01

0 30050

OUTPUT ERROR – V

100 150 200 250

0.008

0.006

0.004

0.002

0

–0.002

–0.004

–0.006

–0.008

–0.01

VS = 6V

G

= –2

V

IN

= 1V p-p

OUTPUT ERROR

C

F

R

G

V

IN

~

V

MID

0.1F

TPC 1. Single-Ended Test Circuit

0.4

0.3

0.2

0.1

0

–0.1

OUTPUT VOLTAGE – V

–0.2

CF = 0pF

CF = 3pF

R

F

R

L

+

0.1F

+

0.1F

6.8F

6.8F

V

OUT

+V

S

–V

TPC 4. Small Signal Step Response

VS = 6V
G

= –2

R

= 10

L

REV. A

–0.3

–0.4

1007550250

125 150 175 200 225 250

TIME – ns

TPC 2. Small Signal Step Response

4

3

2

1

0

–1

OUTPUT VOLTAGE – V

–2

–3

–4

TPC 3. Large Signal Step Response

CF = 0pF

C

= 3pF

F

1007550250 125 150 175 200 225 250

TIME – ns

VS = 6V
G

= –2

R

= 10

L

TPC 5. Large Signal Step Response

TPC 6. 0.1% Settling Time

–5–

AD8391

12

9

6

3

0

–3

–6

–9

OUTPUT VOLTAGE – dBV

–12

–15

–18

0.1 1 100010 100

FREQUENCY – MHz

TPC 7. Output Voltage vs. Frequency

1500

VS = 6V

1250

1000

750

VOH @+85C

V

@+25C

OH

@–40C

V

OH

VS = 6V

= 10

R

L

= –2

G

6

3

0

–3

–6

–9

–12

–15

OUTPUT VOLTAGE – dBV

–18

–21

–24

0.1 1 100010 100

FREQUENCY – MHz

TPC 10. Output Voltage vs. Frequency

1200

VS = 1.5V

1000

800

600

@

V

+85C

OH

@

+25C

V

OH

@

–40C

V

OH

V

OL@

VS = 1.5V

= 10

R

L

G

= –2

–40C

500

V

@+85C

OL

@+25C

V

250

OUTPUT SATURATION VOLTAGE – m V

0

LOAD CURRENT – mA

OL

V

OL

TPC 8. Output Saturation Voltage vs. Load

18

15

12

9

6

3

GAIN – dB

0

–3

–6

–9

0.1 1 100010 100

STANDBY

FULL POWER

FREQUENCY – MHz

TPC 9. Small Signal Frequency Response

@–40C

900800600 7005004003002001000

= 6V

V

S

R

= 10

L

= 2

G

1000

400

200

OUTPUT SATURATION VOLTAGE – m V

0

LOAD CURRENT – mA

V

V

OL@

OL

@

+25C

+85C

450400300 350250200150100500

TPC 11. Output Saturation Voltage vs. Load

18

15

12

9

6

3

GAIN – dB

0

–3

–6

–9

0.1 1 100010 100

STANDBY

FREQUENCY – MHz

VS = 1.5V

R

= 10

L

= 2

G

FULL POWER

TPC 12. Small Signal Frequency Response

500

–6–

REV. A