LM4546A
AC '97 Rev 2 Codec with Sample Rate Conversion and
National 3D Sound
General Description
The LM4546A is an audio codec for PC systems which is
fully PC98 compliant and performs the analog intensive
functions of the AC97 Rev 2 architecture. Using 18-bit
Sigma-Delta A/D's and D/A's, the LM4546A provides 90dB of
Dynamic Range.
The LM4546A was designed specifically to provide a high
quality audio path and 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 2 stereo and 3 mono inputs, each
of which has separate gain, attenuation and mute control.
The LM4546A also provides National's 3D Sound stereo
enhancement.
The LM4546A supports variable sample rate conversion as
defined in the AC97 Rev2 specification. The sample rate for
the A/D and D/A can be programmed separately to convert
any rate between 4kHz - 48kHz with a resolution of 1Hz. The
AC97 architecture separates the analog and digital functions
of the PC audio system allowing both for system design
flexibility and increased performance.
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 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
Advanced power management support
n
Digital 3V and 5V compliant
Applications
n
Desktop PC Audio Systems
n
Portable PC Systems
n
Mobile PC Systems
Block Diagram
20030801
FIGURE 1. LM4546A Block Diagram
November 2002
LM4546A
AC
'97
Rev
2
Codec
with
Sample
Rate
Conversion
and
National
3D
Sound
2002 National Semiconductor Corporation
DS200308
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
-40C to +150C
Input Voltage
-0.3V to V
DD
+0.3V
ESD Susceptibility (Note 5)
2500V
pins 27, 28
1500V
pin 3
750V
ESD Susceptibility (Note 6)
200V
pin 3
100V
Junction Temperature
150C
Soldering Information
LQFP Package
Vapor Phase (60 sec.)
215C
Infrared (15 sec.)
220C
See AN-450 "Surface Mounting and their Effects on
Product Reliability" for other methods of
soldering surface mount devices.
JA
(typ) -- VBH48A
74C/W
Operating Ratings
Temperature Range
T
MIN
T
A
T
MAX
-40C
T
A
85C
Analog Supply Range
4.2V
AV
DD
5.5V
Digital Supply Range
3.0V
DV
DD
5.5V
Electrical Characteristics
(Notes 1, 3)
The following specifications apply for AV
DD
= 5V, DV
DD
= 5V, Fs = 48kHz, single codec configuration, unless otherwise noted.
Limits apply for T
A
= 25C. The reference for 0dB is 1Vrms unless otherwise specified.
Symbol
Parameter
Conditions
LM4546A
Units
(Limits)
Typical
(Note 7)
Limit
(Note 8)
AV
DD
Analog Supply Range
4.2
V (min)
5.5
V (max)
DV
DD
Digital Supply Range
3.0
V (min)
5.5
V (max)
D
IDD
Digital Quiescent Power Supply
Current
D
VDD
= 5V
43
mA
D
VDD
= 3.3V
20
mA
A
IDD
Analog Quiescent Power Supply
Current
53
mA
I
DSD
Digital Shutdown Current
500
A
I
ASD
Analog Shutdown Current
30
A
V
REF
Reference Voltage
2.23
V
PSRR
Power Supply Rejection Ratio
40
dB
Analog Loopthru Mode
Dynamic Range (Note 2)
CD Input to Line Output, -60dB Input
THD+N, A-Weighted
97
90
dB (min)
THD
Total Harmonic Distortion
V
O
= -3dB, f = 1kHz, R
L
= 10k
0.01
0.02
% (max)
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
Input Impedance(Note 2)
40
10
k
(min)
C
IN
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
Step Size
+12dB to -34.5dB
1.5
dB
LM4546A
www.national.com
2
Electrical Characteristics
(Notes 1, 3) (Continued)
The following specifications apply for AV
DD
= 5V, DV
DD
= 5V, Fs = 48kHz, single codec configuration, unless otherwise noted.
Limits apply for T
A
= 25C. The reference for 0dB is 1Vrms unless otherwise specified.
Symbol
Parameter
Conditions
LM4546A
Units
(Limits)
Typical
(Note 7)
Limit
(Note 8)
A
M
Mute Attenuation
86
dB
Analog to Digital Converters
Resolution
18
Bits
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
IN
= -3dB, f=1kHz, R
L
= 10k
0.01
%
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
Digital I/O (Note 2)
V
IL
Low level input voltage
0.30 x
DVDD
V (max)
V
HI
High level input voltage
0.40 x
DVDD
V (min)
V
OH
High level output voltage
0.50 x
DVDD
V (min)
V
OL
Low level output voltage
0.20 x
DVDD
V (max)
I
L
Input Leakage Current
AC Link inputs
10
A
I
L
Tri state Leakage Current
High impedance AC Link outputs
10
A
I
DR
Output drive current
AC Link outputs
5
mA
Digital Timing Specifications (Note 2)
F
BC
BIT_CLK frequency
12.288
MHz
T
BCP
BIT_CLK period
81.4
nS
T
CH
BIT_CLK high
Variation of BIT_CLK period from 50%
duty cycle
20
% (max)
F
SYNC
SYNC frequency
48
kHz
T
SP
SYNC period
20.8
S
T
SH
SYNC high pulse width
1.3
S
T
SL
SYNC low pulse width
19.5
S
T
SETUP
Setup Time
SDATA_IN, SDATA_OUT to falling edge
of BIT_CLK
15
nS (min)
T
HOLD
Hold Time
Hold time of SDATA_IN, SDATA_OUT
from falling edge of BIT_CLK
5
nS (min)
T
RISE
Rise Time
BIT_CLK, SYNC, SDATA_IN or
SDATA_OUT
6
nS (max)
T
FALL
Fall Time
BIT_CLK, SYNC, SDATA_IN or
SDATA_OUT
6
nS (max)
T
RST_LOW
RESET# active low pulse width
For cold reset
1.0
S (min)
T
RST2CLK
RESET# inactive to BIT_CLK start up
For cold reset
162.8
nS (min)
T
SH
SYNC active high pulse width
For warm reset
1.3
S
LM4546A
www.national.com
3
Electrical Characteristics
(Notes 1, 3) (Continued)
The following specifications apply for AV
DD
= 5V, DV
DD
= 5V, Fs = 48kHz, single codec configuration, unless otherwise noted.
Limits apply for T
A
= 25C. The reference for 0dB is 1Vrms unless otherwise specified.
Symbol
Parameter
Conditions
LM4546A
Units
(Limits)
Typical
(Note 7)
Limit
(Note 8)
T
SYNC2CLK
SYNC inactive to BIT_CLK start up
For warm reset
162.8
nS (min)
T
SU2RST
Setup to trailing edge of RESET#
For ATE Test Mode
15
nS (min)
T
RST2HZ
Rising edge of RESET# to Hi-Z
For ATE Test Mode
25
nS (max)
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: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is
functional, but do not guarantee specific performance limits. Electrical Characteristics state DC and AC electrical specifications under particular test conditions which
guarantee 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
JMAX
,
JA
, and the ambient temperature T
A
. The maximum
allowable power dissipation is P
DMAX
= (T
JMAX
T
A
)/
JA
or the number given in Absolute Maximum Ratings, whichever is lower. For the LM4546A, T
JMAX
= 150C.
The typical junction-to-ambient thermal resistance is 74C/W for package number VBH48A.
Note 5: Human body model, 100 pF discharged through a 1.5 k
resistor.
Note 6: Machine Model, 220 pF240 pF discharged through all pins.
Note 7: Typicals are measured at 25C and represent the parametric norm.
Note 8: Limits are guaranteed to National's AOQL (Average Outgoing Quality Level).
LM4546A
www.national.com
4
Timing Diagrams
Clocks
20030810
Data Setup and Hold
20030811
Digital Rise and Fall
20030812
Cold Reset
20030813
Warm Reset
20030814
LM4546A
www.national.com
5
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