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PDF LM4549A Data sheet ( Hoja de datos )
| Número de pieza | LM4549A | |
| Descripción | 2 Multi-Channel Audio Codec | |
| Fabricantes | National Semiconductor | |
| Logotipo |  |
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May 2004
LM4549A
AC ’97 Rev 2.1 Multi-Channel Audio Codec with Sample
Rate Conversion and National 3D Sound
General Description
The LM4549A is an audio codec for PC systems which is
fully PC99 compliant and performs the analog intensive
functions of the AC ’97 Rev 2.1 architecture. Using 18-bit
Sigma-Delta ADCs and DACs, the LM4549A provides 90 dB
of Dynamic Range.
The LM4549A 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 ADCs and DACs
and analog mixers with access to 4 stereo and 4 mono
inputs. Each mixer input has separate gain, attenuation and
mute control and the mixers drive 1 mono and 2 stereo
outputs, each with attenuation and mute control. The
LM4549A supports National’s 3D Sound stereo enhance-
ment and a comprehensive sample rate conversion capabil-
ity. The sample rate for the ADCs and DACs can be pro-
grammed separately with a resolution of 1 Hz to convert any
rate in the range 4 kHz – 48 kHz. Sample timing from the
ADCs and sample request timing for the DACs are com-
pletely deterministic to ease task scheduling and application
software development. These features together with an ex-
tended temperature range also make the LM4549A suitable
for non-PC codec applications.
The LM4549A features the ability to connect several codecs
together using the Extended AC Link configuration of one
dedicated serial data signal to the Controller per codec.
LM4549A systems support up to 8 simultaneous channels of
streaming data on Input Frames (Codec to Controller) while
Output Frames (Controller to Codec) carry 2 streams to
multiple codecs. The LM4549A may also be used in systems
with the National LM4550 to support up to 6 simultaneous
channels of streaming data on Output Frames.
The AC ’97 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
n DAC Dynamic Range
n ADC Dynamic Range
97 dB (typ)
89 dB (typ)
90 dB (typ)
Features
n AC ’97 Rev 2.1 compliant
n High quality Sample Rate Conversion from 4 kHz to 48
kHz in 1 Hz increments
n Multiple codec support
n True Line Level Output with separate gain control
n National’s 3D Sound stereo enhancement circuitry
n Advanced power management support
n External Amplifier Power Down (EAPD) control
n PC-Beep passthrough to Line Out during Initialization or
Cold Reset
n Digital 3.3V and 5V supply options
n Extended Temperature: −40˚C ≤ TA ≤ 85˚C
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
n General and Multi-channel audio frequency systems
© 2004 National Semiconductor Corporation DS200299
www.national.com
1 page  
Electrical Characteristics (Notes 1, 5) The following specifications apply for AVDD = 5V, DVDD = 5V, Fs = 48
kHz, single codec configuration, unless otherwise noted. Limits apply for TA= 25˚C. The reference for 0 dB is 1 Vrms unless
otherwise specified. (Continued)
Symbol
Parameter
Conditions
TCO Output Valid Delay
TRISE
Rise Time
TFALL
TRST_LOW
TRST2CLK
TSH
TSYNC2CLK
TS2_PDOWN
Fall Time
RESET# active low pulse width
RESET# inactive to BIT_CLK start
up
SYNC active high pulse width
SYNC inactive to BIT_CLK start up
AC Link Power Down Delay
TSUPPLY2RST Power On Reset
TSU2RST
TRST2HZ
Setup to trailing edge of RESET#
Rising edge of RESET# to Hi-Z
Output Delay of SDATA_IN from rising
edge of BIT_CLK
BIT_CLK, SYNC, SDATA_IN or
SDATA_OUT
BIT_CLK, SYNC, SDATA_IN or
SDATA_OUT
For Cold Reset
For Cold Reset
For Warm Reset
For Warm Reset
Delay from end of Slot 2 to BIT_CLK,
SDATA_IN low
Time from minimum valid supply levels
to end of Reset
For ATE Test Mode
For ATE Test Mode
LM4549A
Typical Limit
(Note 6) (Note 7)
Units
(Limits)
TBD
15 ns (max)
6 ns (max)
TBD
1.3
TBD
6
1.0
162.8
TBD
162.8
1
ns (max)
µs (min)
ns (min)
µs (min)
ns (min)
µs (max)
1 µs (min)
15 ns (min)
25 ns (max)
Note 1: 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 2: Human body model, 100 pF discharged through a 1.5 kΩ resistor.
Note 3: Machine Model, 220 pF – 240 pF discharged through all pins.
Note 4: The maximum power dissipation must be derated at elevated temperatures and is dictated by TJMAX, θJA, and the ambient temperature TA. The maximum
allowable power dissipation is PDMAX = (TJMAX– TA)/θJA or the number given in Absolute Maximum Ratings, whichever is lower. For the LM4549A, TJMAX = 150˚C.
The typical junction-to-ambient thermal resistance is 74˚C/W for package number VBH48A.
Note 5: All voltages are measured with respect to the ground pin, unless otherwise specified.
Note 6: Typicals are measured at 25˚C and represent the parametric norm.
Note 7: Limits are guaranteed to National’s AOQL (Average Outgoing Quality Level).
Note 8: Loopthrough mode describes a path from an analog input through the analog mixer to an analog output
Note 9: These specifications are guaranteed by design and characterization; they are not production tested.
Note 10: Out of band energy is measured from 28.8 kHz to 100 kHz relative to a 1 Vrms DAC output.
5 www.national.com
5 Page 
Pin Descriptions (Continued)
ANALOG I/O (Continued)
Name
Pin I / O
Functional Description
Mono microphone input
Either MIC1 or MIC2 can be muxed to a programmable boost amplifier with selection by the
MS bit (bit D8) in the General Purpose register, 20h. The boost amplifier gain (0 dB or 20 dB)
is set by the 20dB bit (D6) in the Mic Volume register, 0Eh. Nominal input levels at the two
MIC1
gain settings are 1 Vrms and 0.1 Vrms respectively. The amplifier output is selectable (Record
21 I Select register, 1Ah) by either the right or left channels of the Record Select Mux for
conversion on either or both channels of the stereo ADCs. The amplifier output can also be
accessed at the stereo mixer MIX1 (muting and mixing adjustments via Mic Volume register,
0Eh) where it is mixed equally into both left and right channels of Stereo Mix 3D for access to
the stereo outputs Line Out and Line Level Out. Access to the Mono analog output is
selected by a mux controlled by the MIX bit (D9) in General Purpose register, 20h.
Mono microphone input
Either MIC1 or MIC2 can be muxed to a programmable boost amplifier with selection by the
MS bit (bit D8) in the General Purpose register, 20h. The boost amplifier gain (0 dB or 20 dB)
is set by the 20dB bit (D6) in the Mic Volume register, 0Eh. Nominal input levels at the two
MIC2
gain settings are 1 Vrms and 0.1 Vrms respectively. The amplifier output is selectable (Record
22 I Select register, 1Ah) by either the right or left channels of the Record Select Mux for
conversion on either or both channels of the stereo ADCs. The amplifier output can also be
accessed at the stereo mixer MIX1 (muting and mixing adjustments via Mic Volume register,
0Eh) where it is mixed equally into both left and right channels of Stereo Mix 3D for access to
the stereo outputs Line Out and Line Level Out. Access to the Mono analog output is
selected by a mux controlled by the MIX bit (D9) in General Purpose register, 20h.
Left Stereo Channel Input
This line level input (1 Vrms nominal) is selectable at the left channel of the stereo Record
LINE_IN_L
23
Select Mux for conversion by the left channel ADC. It can also be mixed into the left channel
I of the Stereo Mix 3D signal at MIX1 under the control of the Line In Volume register, 10h. The
LINE_IN_L level can be muted (along with LINE_IN_R) or adjusted from +12 dB to -34.5 dB
in 1.5 dB steps. Stereo Mix 3D is combined into the Stereo Mix signal at MIX2 for access to
the stereo outputs Line Out and Line Level Out.
Right Stereo Channel Input
This line level input (1 Vrms nominal) is selectable at the right channel of the stereo Input
LINE_IN_R
24
Mux for conversion by the right channel ADC. It can also be mixed into the right channel of
I the Stereo Mix 3D signal at MIX1 under the control of the Line In Volume register, 10h. The
LINE_IN_R level can be muted (along with LINE_IN_L) or adjusted from +12 dB to -34.5 dB
in 1.5 dB steps. Stereo Mix 3D is combined into the Stereo Mix signal at MIX2 for access to
the stereo outputs Line Out and Line Level Out.
LINE_OUT_L
35
Left Stereo Channel Output
This line level output (1 Vrms nominal) is fed from the left channel of the Stereo Mix signal
O
from MIX2 via the Master Volume register, 02h. The LINE_OUT_L amplitude can be muted
(along with LINE_OUT_R) or adjusted from 0 dB to -46.5 dB in 1.5 dB steps.
LINE_OUT_R
36
Right Stereo Channel Output
This line level output (1 Vrms nominal) is fed from the right channel of the Stereo Mix signal
O
from MIX2 via the Master Volume register, 02h. The LINE_OUT_R amplitude can be muted
(along with LINE_OUT_L) or adjusted from 0 dB to -46.5 dB in 1.5 dB steps.
Mono Output
This mono line level output (1 Vrms nominal) is fed from either a microphone input (MIC1 or
MONO_OUT
37
MIC2, after boost amplifier) or from the mono sum of the left and right Stereo Mix 3D
O channels from MIX1. The optional National 3D Sound enhancement can be disabled (default)
by the 3D bit (bit D13) in the General Purpose register, 20h. Choice of input is by the MIX bit
(D9) in the same register. MIX=0 selects a microphone input. Output level can be muted or
adjusted from 0 dB to -46.5 dB in 1.5 dB steps via the Mono Volume register, 06h.
11 www.national.com
11 Page | ||
| Páginas | Total 28 Páginas | |
| PDF Descargar | [ Datasheet LM4549A.PDF ] | |
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