National Semiconductor LMH6678 Technical data

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LMH6678
Low Power 2-Channel Central-Office xDSL Driver

LMH6678 Low Power 2-Channel Central-Office xDSL Driver

December 2003

General Description

The LMH6678 is a low power 2-channel differential output
driver utilizing dual current feedback op amps with a fixed
gain of A

The LMH6678 utilizes high integration with low power con­sumption to provide 580 mW at 19.8 dBm line output. The
LMH6678 can also be put into a listen mode to maintain the
termination for receive signals with 100 mW/Ch power dis­sipation.

The LMH6678 has two separate 2-bit power control inputs
compatible with 3.3V CMOS for each channel that enable
independent control of line status. When the drivers for both
channels are shut off, power consumption drops to only 6
mW.

Thermal Shutdown function protects the IC from a shorted
line fault or system over temperature.

The LMH6678 is available in a 5mm x 4mm 24-lead LLP
package.

= +5.4.

V

Block Diagram

Features

AV

=AV

CC1

2/3 Power Mode, Typical values unless specified.
n Low power consumption

— Line power P
— No signal 185 mW/Ch
— Listen mode 100 mW/Ch
— Shutdown mode 3 mW/Ch

n Power Supply

— Analog (AV
— Digital (DV

n Output voltage swing

— Single ended 11.5 V
— Differential 23 V

n Multi tone power ratio, f = 500 kHz 72 dB
n Output current 580 mA
n Thermal shutdown protection
n 5mm x 4mm LLP package
n Low thermal resistance 36˚C/W (θ
n Small PCB footprint

= +12V, AVDD=DVDD= +3.3V, TA= 25˚C,

CC2

= 100 mW 580 mW/Ch

LINE

,AV

CC1

,AVDD) +3.3V

DD

) +12V

CC2

@

RL=31Ω

PP

PP

JA

Application

n Full rate ADSL, ADSL+, ADSL++ or G. Lite linecard
n Remote DSLAMs

)

20084037

© 2003 National Semiconductor Corporation DS200840 www.national.com

Absolute Maximum Ratings (Note 1)

If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/

LMH6678

Distributors for availability and specifications.

ESD Tolerance

Human Body Model 2KV (Note 2)

Machine Model 200V (Note 8)

Differential

V

IN

Supply Voltages

AV

– AGND or AV

CC1

AGND +13.2V

– DGND +3.6V

DV

DD

AV

– AGND +3.6V

DD

DGND − AGND

AV

–AV

AV

CC1

DD

–DV

CC2

DD

Voltage at Input Pin

Analog Input AV

CC2

–

(AV

CC1

±

3V

±

0.2V

±

0.2V

±

0.2V

) +0.8V,

CC2

AGND −0.8V

Digital Control Input DV

DD

+0.8V,

DGND −0.8V

Soldering Information

Infrared or Convection (20 sec.) 235˚C

Storage Temperature Range −65˚C to +150˚C

Junction Temperature (Note 4) +150˚C

Operating Ratings (Note 1)

Supply Voltage

AV

to AGND +12V±10%

CC1

AV

to AGND +12V±10%

CC2

DV

to DGND +3.3V±10%

DD

AV

to AGND +3.3V±10%

DD

Operating Temperature Range
(Note 3), (Note 4)

Package Thermal Resistance (θ
(Note 4)

)

JA

−40˚C to +85˚C

36˚C/W

Electrical Characteristics Unless otherwise specified, all limits guaranteed for T

+12V, DV

Symbol Parameter Conditions Min

=AVDD= +3.3V. DGND = AGND = 0V, 2/3 Power Mode. See (Note 9).

DD

(Note 6)

= 25˚C, AV

J

Typ

(Note 5)

CC1

Max

(Note 6)

=AV

CC2

Units

Dynamic Performance

f

CL

SR Slew Rate (Note 7) V

−3 dB BW RL= 100Ω 50 MHZ

=±2.4V, RL= 100Ω 700 V/µs

IN_DIFF

Distortion and Noise Response

HD2 2nd Harmonic Distortion fc = 1 MHz, V

fc = 200 kHz, V

HD3 3

rd

Harmonic Distortion fc = 1 MHz, VO=2VPP,RL=31Ω −57

fc = 200 kHz, V

=2VPP,RL=31Ω −91

O

=2VPP,RL=31Ω −98

O

=2VPP,RL=31Ω −71

O

dBc

dBc

MTPR Multi-Tone Power Ratio f = 500 kHz 72 dBc

V

IN

Differential Output Noise 100 kHz to 10 MHz 57 nV/

Input Characteristics

V

IN

R

IN

Input DC Voltage Common Mode 6.04 6.1 6.16 V

Input Resistance Differential

= 10 µA from +IN to −IN

I

DIFF

14.4 20 28.4 kΩ

Transfer Characteristics

A

V

Voltage Gain V

= −1 to 1V, No Load +5.37 +5.40 +5.48 V/V

IN_DIFF

PSRR Power Supply Rejection Ratio −108 dB

Xt Cross Talk f = 1 MHz, R

V

O

I

SC

Output Voltage Swing High V

Output Voltage Swing Low V

IN_DIFF

IN_DIFF

V

IN_DIFF

IN_DIFF

IN_DIFF

V

IN_DIFF

Output Short Circuit Current Sourcing to Ground +800

Sinking to Ground −800

= 100Ω −95

L

=±2.4V, No Load 11.85

=±2.4V, RL=31Ω 11.68 11.75

=±2.4V, I

= 580 mA 11.64 11.74

OUT

=±2.4V, No Load 0.15

=±2.4V, RL=31Ω 0.25 0.36

=±2.4V, I

= 580 mA 0.31 0.39

OUT

VV

VV

mA

=

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LMH6678

Electrical Characteristics Unless otherwise specified, all limits guaranteed for T

+12V, DV

Symbol Parameter Conditions Min

I

OUT

V

OC

V

OS

Power Supply (Note 10), (Note 11)

I

CC

I

DV

I

AV

Logic Inputs

V

IH

V

IL

I

IH

I

IL

Charge Pump

f

CP

V

HIGH

V

LOW

=AVDD= +3.3V. DGND = AGND = 0V, 2/3 Power Mode. See (Note 9). (Continued)

DD

(Note 6)

Output Current V

Sourcing, R
Sinking, R

IN_DIFF

=±2.4V

=20Ω

L

=20Ω

L

Output Common Mode Voltage 5.89 6 6.05 V

Output Offset Voltage −40 0 +40 mV

AVCCQuiescent Supply Current B01 B11 B02 B12

Full Power L L L L 28.6 33 36.9

2/3 Power H L H L 18.6 22 25.4

1/3 Power L H L H 9.2 12 14.3

Shutdown H H H H 0.2 .95

DVDDQuiescent Supply Current B01 B11 B02 B12

Full Power L L L L 11 16 19

2/3 Power H L H L 7 12 15

1/3 Power L H L H 3 7 10.3

Shutdown H H H H 0.05 .14

AVDDQuiescent Supply Current All Power Modes .8 1.1 1.4 mA

Input High Voltage 2.7 3.3 V

Input Low Voltage 0 0.5 V

Input High Current

Input Low Current

@

VIH= 3.3V −0.5 0.02 +0.5 µA

@

VIH= 0V −0.5 0.02 +0.5 µA

Charge Pump Frequency Measure at DRIVE at Full Power 2.43 2.75 MHz

Charge Pump High Average

Measure at CstoreH at Full Power +14.6 V

Voltage

Charge Pump Low Average

Measure at CstoreL at Full Power −2.7V V

Voltage

= 25˚C, AV

J

Typ

(Note 5)

±

580 mA

=AV

CC1

Max

(Note 6)

CC2

=

Units

mA

mA

Note 1: Absolute maximum ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is
intended to be functional, but specific performance is not guaranteed. For guaranteed specifications and the test conditions, see the Electrical Characteristics.

Note 2: Human body model, 1.5kΩ in series with 100pF.

Note 3: Continuous short circuit operation at elevated ambient temperature can result in exceeding the maximum allowed junction temperature of 150˚ C.

Note 4: The maximum power dissipation is a function of T

(T

J(MAX)-TA

Note 5: Typical Values represent the most likely parametric norm.

Note 6: All limits are guaranteed by testing or statistical analysis.

Note 7: Slew rate is the slowest of the rising and falling slew rates.
Note 8: Machine Model, 0Ω in series with 200 pF.

Note 9: Electrical table values apply only for factory testing conditions at the temperature indicated. Factory testing conditions result in very limited self-heating of

the device such that T
Absolute maximum ratings indicate junction temperature limits beyond which the device may be permanently degraded, either mechanically or electrically.

Note 10: Quiescent supply current specification apply for the condition of no input signal. See application section for information on power consumption as a
function of output power, power control bit settings and external resistor R

Note 11: “L” is V

)/θJA. All numbers apply for packages soldered directly onto a PC board. Die attach pad is electrically connected to AGND.

. No guarantee of parametric performance is indicated in the electrical tables under conditions of internal self heating where T

J=TA

and “H” is VIH.

IL

, θJA, and TA. The maximum allowable power dissipation at any ambient temperature is PD=

J(MAX)

.

ADJ

>

TA.

J

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Connection Diagram

LMH6678

Note: Die attach pad is electrically connected to AGND

20084038

Ordering Information

Package Part Number Package Marking Transport Media NSC Drawing

LLP

LMH6678LQ

LMH6678LQX 4.5k Units Tape and Reel

L6678LQ

1k Units Tape and Reel

LQA24A

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Typical Performance Characteristics

LMH6678

Single-Ended Small Signal Frequency Response

@

RL= 100Ω

20084010

Medium Signal Pulse Response

@

RL= 100Ω, 1 MHz

Single-Ended Small Signal Frequency Response

@

RL=36Ω

20084011

Medium Signal Pulse Response

@

RL=36Ω, 1 MHz

Large Signal Pulse Response

@

RL= 100Ω, 1 MHz

20084005

20084006

Large Signal Pulse Response

@

RL=36Ω, 1 MHz

20084008 20084007

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Typical Performance Characteristics (Continued)

LMH6678

Single-Ended Small Signal Frequency Response

@

ZL= 100Ω||100 pF

20084014

Single-Ended Small Signal Frequency Response

@

ZL=36Ω||100 pF

Output Swing@ZL= 100Ω||100 pF, 1 MHz Output Swing@ZL=36Ω||100 pF, 1 MHz

20084013

20084003

20084001

Output Swing@ZL= 100Ω||100 pF, 5 MHz Output Swing@ZL=36Ω||100 pF, 5 MHz

20084004

20084002

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