NSC LM4549VH Datasheet

February 1999

LM4549
AC ’97 Rev 2.1 Codec with Sample Rate Conversion and
National 3D Sound

LM4549 AC ’97 Rev 2.1 Codec with Sample Rate Conversion and National 3D Sound

General Description

The LM4549 is an audio codec for PC systems which is fully
PC98 compliant and performs the analog intensivefunctions
of the AC97 Rev2.1 architecture. Using 18-bit Sigma-Delta
A/D’s and D/A’s, the LM4549 provides 90dB of Dynamic
Range.

The LM4549 was designed specifically to provide a high
quality audiopathand provide all analog functionality in a PC
audio system. It features full duplex stereo A/D’s and D/A’s
and an analog mixer with 4 stereo and 3 mono inputs, each
of which has separate gain, attenuation and mute control.
The codec features a second Line Output known as True
Line Level Out that is identical to Line Out but with indepen­dent volume control. The LM4549 also features National’s
3D Sound stereo enhancement and variable sample rate
conversion. The sample rate for the A/D and D/A can be pro­grammed separately with a resolution of 1Hz to convert any
rate between 4kHz-48kHz.

TheAC97 architecture separates the analog and digital func­tions of the PC audio system allowing both for system design
flexibility and increased performance.

Block Diagram

Key Specifications

n Analog Mixer Dynamic Range 97dB (typ)
n D/A Dynamic Range 89dB (typ)
n A/D Dynamic Range 90dB (typ)

Features

n AC’97 Rev 2.1 compliant
n National’s 3D Sound circuitry
n High quality Sample Rate Conversion (SRC) from 4kHz

to 48kHz in 1Hz increments.

n Multiple Codec Support
n External Amplifier Power Down (EAPD) control from

codec

n PC-Beep passthrough to Line Out while reset is held

active low

n True Line Level Output with volume control independent

of Line Out

n Digital 3V and 5V compliant

Applications

n Desktop PC Audio Systems on PCI cards, AMR cards,

or with motherboard chips sets featuring AC-Link

n Portable PC Systems as on MDC cards, or with a

chipset or accelerator featuring AC-Link

DS101035-1

FIGURE 1. LM4549 Block Diagram

© 1999 National Semiconductor Corporation DS101035 www.national.com

Absolute Maximum Ratings (Note 3)

If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.

Supply Voltage 6.0V
Storage Temperature −65˚C to +150˚C
Input Voltage −0.3V to V
ESD Susceptibility (Note 5) 2000V

pin 3 750V

ESD Susceptibility (Note 6) 200V

pin 3 100V

Junction Temperature 150˚C

DD

+0.3V

Soldering Information

TQFP Package
Vapor Phase (60 sec.) 215˚C
Infrared (15 sec.) 220˚C

See AN-450 ″Surface Mounting and their Effects on
Product Reliability″ for other methods of
soldering surface mount devices.

θ

(typ)—VBH48A 74˚C/W

JA

Operating Ratings

Temperature Range

T

≤ TA≤ T

MIN

MAX

Analog Supply Range 4.2V ≤ AV

Digital Supply Range 3.0V ≤ DV

−40˚C ≤ TA≤ 85˚C

DD
DD

≤ 5.5V
≤ 5.5V

Electrical Characteristics (Notes 1, 3)

The following specifications apply for AVDD= 5V, DVDD= 5V, Fs = 48kHz, single codec configuration, unless otherwise noted.
Limits apply for TA= 25˚C. The reference for 0dB is 1Vrms unless otherwise specified.

Symbol Parameter Conditions

AV

DD

Analog Supply Range 4.2 V (min)

Typical

(Note 7)

LM4549

Limit

(Note 8)

5.5 V (max)

DV

DD

Digital Supply Range 3.0 V (min)

5.5 V (max)

D

IDD

A

IDD

I

DSD

I

ASD

V

REF

Digital Quiescent Power Supply
Current

Analog Quiescent Power Supply

D

=5V 43 mA

VDD

= 3.3V 20 mA

D

VDD

53 mA

Current
Digital Shutdown Current 500 µA
Analog Shutdown Current 30 µA
Reference Voltage 2.23 V

PSRR Power Supply Rejection Ratio 40 dB

Analog Loopthru Mode

Dynamic Range (Note 2)

THD Total Harmonic Distortion V

CD Input to Line Output, -60dB Input
THD+N, A-Weighted

= -3dB, f = 1kHz, RL= 10kΩ 0.01 0.02

O

97 90 dB (min)

Analog Input Section

V

IN

Line Input Voltage 1 Vrms
Mic Input with 20dB Gain 0.1 Vrms

Mic Input with 0dB Gain 1 Vrms
Xtalk Crosstalk CD Left to Right -95 dB
Z

IN

C

IN

Input Impedance(Note 2) 40 10 kΩ (min)

Input Capacitance 15 pF

Interchannel Gain Mismatch CD Left to Right 0.01 dB

Record Gain Amplifier - A/D

A

S

Step Size 0dB to 22.5dB 1.5 dB

Mixer Section

A

S

A

M

Step Size +12dB to -34.5dB 1.5 dB

Mute Attenuation 86 dB

Analog to Digital Converters

Resolution 18 Bits

Units

(Limits)

%

(max)

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Electrical Characteristics (Notes 1, 3) (Continued)

The following specifications apply for AVDD= 5V, DVDD= 5V, Fs = 48kHz, single codec configuration, unless otherwise noted.
Limits apply for TA= 25˚C. The reference for 0dB is 1Vrms unless otherwise specified.

Symbol Parameter Conditions

Analog to Digital Converters

Dynamic Range (Note 2) -60dB Input THD+N, A-Weighted 90 86 dB (min)
Frequency Response -1dB Bandwidth 20 kHz

Digital to Analog Converters

Resolution 18 Bits
Dynamic Range (Note 2) -60dB Input THD+N, A-Weighted 89 85 dB (min)

THD Total Harmonic Distortion V

= -3dB, f=1kHz, RL= 10kΩ 0.01

IN

Frequency Response 20 - 21k Hz
Group Delay (Note 2) 2 mS (max)
Out of Band Energy -40 dB
Stop Band Rejection 70 dB

D

T

Discrete Tones -96 dB

True Line Level Output Volume Section

A

S

A

M

Step Size 0dB to -46.5dB 1.5 dB
Mute Attenuation 86 dB

Digital I/O (Note 2)
V

IL

V

HI

V

OH

V

OL

I

L

I

L

I

DR

Low level input voltage

High level input voltage

High level output voltage

Low level output voltage
Input Leakage Current AC Link inputs

Tri state Leakage Current High impedance AC Link outputs

Output drive current AC Link outputs 5 mA
Digital Timing Specifications (Note 2)
F

BC

T

BCP

T

CH

F

SYNC

T

SP

T

SH

T

SL

T

SETUP

T

HOLD

T

RISE

T

FALL

T

RST_LOW

T

RST2CLK

BIT_CLK frequency 12.288 MHz

BIT_CLK period 81.4 nS

BIT_CLK high

Variation of BIT_CLK period from 50

duty cycle
SYNC frequency 48 kHz
SYNC period 20.8 µS
SYNC high pulse width 1.3 µS
SYNC low pulse width 19.5 µS

Setup Time

Hold Time

Rise Time

Fall Time

SDATA_IN, SDATA_OUT to falling

edge of BIT_CLK

Hold time of SDATA_IN, SDATA_OUT

from falling edge of BIT_CLK

BIT_CLK, SYNC, SDATA_IN or

SDATA_OUT

BIT_CLK, SYNC, SDATA_IN or

SDATA_OUT
RESET# active low pulse width For cold reset 1.0 µS (min)
RESET# inactive to BIT_CLK start

up

For cold reset 162.8 nS (min)

%

Typical

(Note 7)

LM4549

(Note 8)

(Limits)

Limit

0.30 x
DVDD

0.40 x
DVDD

0.50 x
DVDD

0.20 x
DVDD

±
±

±

V (max)

V (min)

V (min)

V (max)

10 µA
10 µA

%

20

15 nS (min)

5 nS (min)

6 nS (max)

6 nS (max)

Units

%

(max)

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Electrical Characteristics (Notes 1, 3) (Continued)

The following specifications apply for AVDD= 5V, DVDD= 5V, Fs = 48kHz, single codec configuration, unless otherwise noted.
Limits apply for TA= 25˚C. The reference for 0dB is 1Vrms unless otherwise specified.

Symbol Parameter Conditions

Digital Timing Specifications (Note 2)

T

SH

T

SYNC2CLK

T

SU2RST

T

RST2HZ

Note 1: All voltages are measured with respect to the ground pin, unless otherwise specified.
Note 2: These specifications are guaranteed by design and characterization; they are not production tested.
Note 3:

tional, but do not guarantee specific performance limits.
antee specific performance limits. This assumes that the device is within the Operating Ratings. Specifications are not guaranteed for parameters where no limit is
given, however, the typical value is a good indication of device performance.

Note 4: The maximum power dissipation must be derated at elevated temperatures and is dictated by T
allowable power dissipation is P
typical junction-to-ambient thermal resistance is 74˚C/W for package number VBH48A.

Note 5: Human body model, 100 pF discharged through a 1.5 kΩ resistor.
Note 6: Machine Model, 220 pF–240 pF discharged through all pins.
Note 7: Typicals are measured at 25˚C and represent the parametric norm.
Note 8: Limits are guaranteed to National’s AOQL (Average Outgoing Quality Level).

SYNC active high pulse width For warm reset 1.3 µS
SYNC inactive to BIT_CLK start up For warm reset 162.8 nS (min)
Setup to trailing edge of RESET# For ATE Test Mode 15 nS (min)
Rising edge of RESET# to Hi-Z For ATE Test Mode 25 nS (max)

Absolute Maximum Ratings

indicate limits beyond which damage to the device may occur.

=(T

DMAX

JMAX–TA

Electrical Characteristics

)/θJAor the number given in Absolute Maximum Ratings, whichever is lower. For the LM4549, T

state DC and AC electrical specifications under particular test conditions which guar-

Operating Ratings

JMAX

indicate conditions for which the device is func-

, θJA, and the ambient temperature TA. The maximum

Typical

(Note 7)

LM4549

Limit

(Note 8)

JMAX

(Limits)

= 150˚C. The

Units

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Timing Diagrams

Clocks

DS101035-10

Data Setup and Hold

DS101035-11

Digital Rise and Fall

Cold Reset

Warm Reset

DS101035-12

DS101035-13

DS101035-14

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Typical Application

FIGURE 2. LM4549 Typical Application Circuit for a Single Codec Application

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DS101035-3