Datasheet
12
LM4550
NC
30
V
REF_OUT
SYNC
SDATA_OUT
BIT_CLK
RESET#
SDATA_IN
1
2
5
3
4
R5
6.81k
R24
47k
HP_OUT_L
HP_OUT_C
HP_OUT_R
RESET#
39
40
41
11
AV
DD
25
+
C16
1 PF
C9
0.1 PF
AV
SS
1
2
5
3
4
J5
HEADPHONE
JACK
J6
NC
R23
10k
C6
220 pF
C5
220pF
R22
10k
+ +
C31
C32
220 PF
C7
220 pF
R4
2.2k
R2
47
SYNC
10
SDATA_IN
8
SDATA_OUT
5
BIT_CLK
6
26
29
EAPD
MONO_OUT
47
37
DV
DD1
1
DV
DD2
9
DV
SS1
DV
SS2
PC_BEEP
LINE_IN_L
LINE_IN_R
CD_L
CD_GND
CD_R
AUX_L
AUX_R
MIC1
MIC2
VIDEO_R
VIDEO_L
PHONE
ID0#
ID1#
V
REF
3DN 3DP XTAL_OUTXTAL_IN
+
33
34
C8
0.022 PF
2 3
Y1
33 pF
R25
24.576 MHz
+
C28
1 PF
220PF
LINE_OUT_L
LINE_OUT_R
35
36
NC
NC
32
31
NC
38
1 M:
33 pF
C1 C2
R1
0:
AGNDDGND
+
15
28
23
24
18
19
20
14
16
17
22
46
45
13
27
21
7
4
NC
42
C4
220 pF
R21
10k
+
C27
1 PF
C3
220 pF
R20
10k
+
C26
1 PF
CIN
48
0.1 PF
C12
C13
3.3 PF
C30
0.1 PF
1
2
5
3
4
AV
DD
+
C18
1 PF
R6
6.81k
1
2
5
3
4
+
C29
2.2 PF
R3
1k
+
C17
1 PF
R19
10k
R7
6.81k
+
C19
1 PF
R8
6.81k
J2
MICROPHONE
JACK
LINE INPUT JACK
J1
LINE_IN
LINE OUTPUT JACK
1
2
3
4
J3
CD INPUT HEADER
1
2
3
4
AUXILIARY INPUT
HEADER
R15
6.81k
+
C23
1 PF
R16
6.81k
R17
6.81k
+
C24
1 PF
R18
6.81k
R11
6.81k
+
C21
1 PF
R12
6.81k
R13
6.81k
+
C22
1 PF
R14
6.81k
R9
6.81k
+
C20
1 PF
R10
6.81k
CD_IN
MIC1
LINE_OUT
HP_OUT
J4
AUX_IN
PC_BEEP
U1
+3.3V
LM78M05
3
V
IN
V
OUT
1
2
U2
GND
+7.5V - +20V
C34
0.33 PF
C33
0.1 PF
AV
DD
Digital
Supply
NC
43
NC
44
Optional for LM4550. Will improve transient
response.
Optional. Not required if LM78M05 is < 4 in. from an
input filtering capacitor
+
C25
1 PF
C14
1 PF
C11
0.1 PF
+
L1 27 nH.
OBSOLETE
LM4550
www.ti.com
SNAS032F –SEPTEMBER 2001–REVISED APRIL 2013
APPLICATION HINTS
• The LM4550 must be initialized by using RESET# to perform a Power On Reset as shown in the Power On
Reset Timing Diagram
• V
REF
must be pulled high to AV
DD
with a 10 kΩ resistor to ensure correct operation
• Don't leave unused inputs floating. Tie all unused inputs together and connect to Analog Ground through a
capacitor (e.g. 0.1 µF)
• Do not leave CD_GND floating when using the CD stereo input. CD_GND is the AC signal reference for the
CD channels and should be connected to the CD source ground (Analog Ground may also be acceptable)
through a 1 µF capacitor
• If using a non-standard AC Link controller take care to keep the SYNC and SDATA_OUT signals low during
Cold Reset to avoid accidentally activating the ATE or Vendor test modes
• The PC_Beep input should be explicitly muted if not used since it defaults to 0 dB gain on reset, unlike the
mute default of the other analog inputs
Figure 9. LM4550 Reference Design, Typical Application, Single Codec, 1 Vrms and 2 Vrms inputs, EMC
output filters
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