LM4546VHX National Semiconductor, LM4546VHX Datasheet - Page 12

• Manufacturer Part Number: LM4546VHX
• Description: IC AUDIO CODEC '97 18BIT 48LQFP
• Manufacturer: National Semiconductor
• Type: Audio Codec '97r

Specifications of LM4546VHX

• 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: *LM4546VHX

Application Information
AC Link Serial Interface Protocol
10098504
FIGURE 3. AC 97 Bidirectional Audio Frame
10098506
FIGURE 4. AC Link Audio Output Frame
AC Link Output Frame: SDATA_OUT (output from
controller, input to LM4546)
The audio output frame (output from AC '97 Controller) con-
tains control and PCM data targeted for the LM4546 control
registers and stereo DAC. The Tag slot, slot 0, contains 16
bits that tell the AC Link interface circuitry on the LM4546 the
validity of the following data slots.
A new audio output frame is signaled with a low to high tran-
sition of SYNC. SYNC is synchronous to the rising edge of
BIT_CLK. On the next rising edge of BIT_CLK, the AC '97
Controller drives SDATA_OUT with the first bit of slot 0. The
LM4546 samples SDATA_OUT on the falling edge of
BIT_CLK. The AC '97 Controller will continue outputting the
10098505
SDATA_OUT stream on each successive rising edge of
BIT_CLK.
FIGURE 5. Start of Audio Output Frame
SDATA_OUT Slot 0: Tag Phase
The first bit of slot 0 is designated the "Valid Frame" bit. If this
bit is 1, it indicates that the current data frame contains at least
one slot of valid data and the LM4546 will further sample the
next four bits to determine which frames do in fact have valid
data. Valid slots are signified by a 1 in their respective slot bit
position.
www.national.com
12
100985 Version 4 Revision 1
Print Date/Time: 2009/04/29 09:52:43