LM4540VH National Semiconductor, LM4540VH Datasheet - Page 15

• Manufacturer Part Number: LM4540VH
• Description: IC AUDIO CODEC '97 18BIT 48LQFP
• Manufacturer: National Semiconductor
• Type: Audio Codec '97r

Specifications of LM4540VH

• Data Interface: Serial
• Resolution (bits): 18 b
• Number Of Adcs / Dacs: 2 / 2
• Sigma Delta: Yes
• Dynamic Range, Adcs / Dacs (db) Typ: 90 / 89
• Voltage - Supply, Analog: 4.2 V ~ 5.5 V
• Voltage - Supply, Digital: 3 V ~ 5.5 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 48-LQFP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Other names: *LM4540VH

Application Information
Mixer Input Volume Registers (Index 0Ch - 12h, 18h)
These registers control the input volume controls including
mute. Each volume control is 5 bit which provides from a
range of +12dB gain to 34.5dB attenuation. For stereo ports,
the left and right levels can be independently set. Muting a
given port is accomplished by setting the MSB to 1. Setting
the MSB to 1 for stereo ports mutes both the left and right
channel. Register 0Eh has an additional 20dB boost for a mi-
crophone level input. This is enabled by setting bit 6 of reg-
ister 0Eh to 1.
Record Select Register (1Ah)
This register independently controls the source for the right
and left channel which will be recorded by the stereo ADC.
The default value is 0000h which corresponds to Mic in.
Record (Input) Gain Register (1Ch)
This registers controls the Record (Input) Gain level for the
stereo input selected via the Record Select Control Register
(1Ah). The gain can be programmed from 0dB to +22.5dB in
1.5dB steps. The level for the left and right channel can be
individually controlled. The input can also be muted by set-
ting the MSB to 1.
SR2:SR0
Default: 8008h (mono regs.), 8808h (stereo regs.)
SL2:SL0
Mute
0
0
0
1
0
1
2
3
4
5
6
7
0
1
2
3
4
5
6
7
Gx4:Gx0
XXXXX
00000
01000
01111
Right Record Source
Left Record Source
Stereo Mix (R)
Stereo Mix (L)
Mono Mix (R)
Mono Mix (L)
Line In (R)
Line In (L)
CD In (R)
CD In (L)
not used
not used
not used
not used
Phone
Phone
Mic
Mic
34.5dB attenuation
+12dB gain
Function
0dB gain
(Continued)
mute
15
General Purpose Register (20h)
This register controls many miscellaneous functions imple-
mented on the LM4540. The miscellaneous functions include
POP which allows the PCM to bypass the National 3D
Sound circuitry, 3D which enables or disables the National
3D Sound circuitry, MIX which selects the MONO_OUT
source, MS which selects the microphone mux source, and
LPBK which connects the output of the stereo ADC to the in-
put of the stereo DAC. LPBK provides a digital loopthru path
when enabled.
Powerdown Control / Status Register (26h)
This read/write register is used to monitor subsystem readi-
ness and program LM4540 powerdown states. The lower
half of this register is read only with a 1 indicated the sub-
section is ready. Writing to the lower 8 bits will have no effect.
When the AC Link Codec Ready indicator bit (SDATA_IN
slot 0, bit 15) is a 1 it indicates that the AC Link and AC ’97
registers are in a fully operational state. The AC ’97 Control-
ler must further probe the Powerdown Control / Status Reg-
ister to determine exactly which subsections are ready.
The supported powerdown modes are as follows.
Reserved Registers (28h - 7Ah)
Do not write to these registers as they are reserved.
Default: 8000h
LPBK
Mute
POP
DAC
ADC
PRO
REF
ANL
PR1
PR2
PR3
PR4
PR5
PR6
MIX
BIT
BIT
BIT
MS
3D
0
0
1
PCM in ADC’s and Input Mux powerdown
PCM out path and mute, 0 = pre 3D, 1 =
Analog Mixer powerdown (VREF still on)
Gx3:Gx0
Digital Interface (AC Link) powerdown
Analog Mixer powerdown (VREF off)
Mono output select 0 = Mix, 1 = Mic
XXXX
ADC section ready to transmit data
1111
0000
National 3D Sound on / off 1 = on
DAC section ready to accept data
Mic select 0 = Mic1 1 = Mic2
PCM out DAC’s powerdown
Vref’s up to nominal level
Analog mixers ready
ADC/DAC loopback
Internal Clk disable
(external clk off)
Function
Function
Function
not used
post 3D
22.5dB gain
Function
0dB gain
mute
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