LM4550BVH/NOPB National Semiconductor, LM4550BVH/NOPB Datasheet - Page 20

• Manufacturer Part Number: LM4550BVH/NOPB
• Description: IC AC '97 AUDIO CODEC 48-LQFP
• Manufacturer: National Semiconductor
• Type: Audio Codec '97r

Specifications of LM4550BVH/NOPB

• 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
• Audio Codec Type: Stereo
• No. Of Adcs: 2
• No. Of Dacs: 2
• No. Of Input Channels: 8
• No. Of Output Channels: 3
• Adc / Dac Resolution: 18bit
• Sampling Rate: 48kSPS
• Interface Type: Serial
• Supply Voltage Range: 3V To 5.5V, 4.2V
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: *LM4550BVH; *LM4550BVH/NOPB; LM4550BVH

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AC Link Serial Interface Protocol
SDATA_OUT: Slots 3 & 4 – PCM Playback Left/Right
Channels
Slots 3 and 4 are 20-bit fields used to transmit PCM data to
the left and right channels of the stereo DAC when the codec
is in Primary mode or Secondary mode 1. Any unused bits
should be stuffed with zeros. The LM4550 DACs have 18-bit
resolution and will therefore use the 18 MSBs of the 20-bit
PCM data (MSB justified). The AC ’97 Rev 2.1 specification
allocates the Left channel of 5.1 Audio to slot 3 and the Right
channel to slot 4.
SDATA_OUT: Slots 7 & 8 – PCM Playback Left/Right
Surround
Slots 7 and 8 are 20-bit fields used to transmit PCM data to
the left and right channels of the stereo DAC when the codec
is in Secondary mode 2. Any unused bits should be stuffed
with zeros. The LM4550 DACs have 18-bit resolution and will
therefore use the 18 MSBs of the 20-bit PCM data (MSB
justified). The AC ’97 Rev 2.1 specification allocates the Left
Surround channel of 5.1 Audio to slot 7 and the Right Sur-
round channel to slot 8.
AC LINK INPUT FRAME:
SDATA_IN, CONTROLLER INPUT FROM LM4550 OUTPUT
The AC Link Input Frame contains status and PCM data from
the LM4550 control registers and stereo ADC. Input Frames
are carried on the SDATA_IN signal which is an input to the
AC ’97 Digital Audio Controller and an output from the
LM4550 codec. As shown in Figure 3, Input Frames are
constructed from thirteen time slots: one Tag Slot followed by
twelve Data Slots. The Tag Slot, Slot 0, contains 16 bits of
(Continued)
Bits
19:0
Description
PCM Audio
(Left /Right
Channels)
SLOTS 3 & 4, OUTPUT FRAME
Data
Slots used to stream data to
DAC when codec is in Primary
or Secondary 1 modes.
Set unused bits to "0"
Comment
FIGURE 6. AC Link Input Frame
20
SDATA_OUT: Slots 6 & 9 – PCM Playback (Center/LFE)
Slots 6 and 9 are 20-bit fields used to transmit PCM data to
the left and right channels of the stereo DAC when the codec
is in Secondary mode 3. Any unused bits should be stuffed
with zeros. The LM4550 DACs have 18-bit resolution and will
therefore use the 18 MSBs of the 20-bit PCM data (MSB
justified). The AC ’97 Rev 2.1 specification allocates the
Center channel of 5.1 Audio to slot 6 and the LFE (Low
Frequency Enhancement) channel to slot 9.
SDATA_OUT: Slots 5, 10, 11, 12 – Reserved
These slots are not used by the LM4550 and should all be
stuffed with zeros by the AC ’97 Controller.
which 5 are used by the LM4550. One is used to indicate
that the AC Link interface is fully operational and the other 4
to indicate the validity of the data in the four of the twelve
following Data Slots that are used by the LM4550. Each
Frame consists of 256 bits with each of the twelve data slots
containing 20 bits.
Bits
19:0
Bits
19:0
(Center/ LFE
Description
Description
PCM Audio
PCM Audio
(Left/Right
Surround)
Surround)
SLOTS 7 & 8, OUTPUT FRAME
SLOTS 6 & 9, OUTPUT FRAME
Data
Data
Slots used to stream data to
DAC when codec is in
Secondary 2 mode.
Set unused bits to "0"
Slots used to stream data to
DAC when codec is in
Secondary 3 mode.
Set unused bits to "0"
Comment
Comment
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