Datasheet

OBSOLETE

LM4550

SNAS032F –SEPTEMBER 2001–REVISED APRIL 2013

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Table 8. SLOT 2, OUTPUT FRAME

Bits Description Comment

19:4 Control Register Write Data Controller should stuff with zeros if operation is “read”

3:0 Reserved Set to "0"

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.

Table 9. SLOTS 3 & 4, OUTPUT FRAME

Bits Description Comment

Slots used to stream data to DAC when codec is in Primary or Secondary 1

PCM Audio Data

19:0 modes.

(Left /Right Channels)

Set unused bits to "0"

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 Surround channel to slot 8.

Table 10. SLOTS 7 & 8, OUTPUT FRAME

Bits Description Comment

PCM Audio Data Slots used to stream data to DAC when codec is in Secondary 2 mode.

19:0

(Left/Right Surround) Set unused bits to "0"

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.

Table 11. SLOTS 6 & 9, OUTPUT FRAME

Bits Description Comment

PCM Audio Data Slots used to stream data to DAC when codec is in Secondary 3 mode.

19:0

(Center/ LFE Surround) Set unused bits to "0"

Product Folder Links: LM4550