AD1881A
5AV
DD
R1
100k⍀
STEREO
HP/SPEAKER
OUTPUT
C2
100F
C1
1F
F1
R2
49.9k⍀
U1
J1
R3
1k⍀
C3
470pF
FB
600Z
AD1881A
U2
EAPD/CHAIN_IN
SSM2250RU
C5
NC
NC
R4
49.9k⍀
100F
F2
LEFT IN
LEFT OUT/BLT
STEREO
3.5mm JACK
LINE_OUT_L
LIN_OUT_R
R5
1k⍀
C6
470pF
FB
600Z
C4
0.33F
SHUTDOWN
VDO
BTL+
SE/BTL
LS1
INTERNAL
MONO
SPEAKER
BYPASS
RIGHT OUT
NC
R6
49.9k⍀
GND
MONO_OUT
RIGHT IN
NC
4⍀
C8
0.1F
C7
0.33F
NC = NO CONNECT
R7
49.9k⍀
Figure 15. Using the SSM2250 Amplifier for Stereo and Mono Output
GROUNDING AND LAYOUT
To reduce noise and emissions, Analog Devices recommends a split ground plane as shown in Figure 16. The purpose of splitting the
ground plane is to create a low noise analog area that is somewhat isolated from the digital ground current noise generated by the
system’s logic. All the analog circuitry should be placed on the analog ground plane area.
For reference purposes, and to return power supply currents, the analog and digital ground planes must be connected at some point,
ideally a small bridge under or near the Codec should be provided. A 0 Ω resistor or a ferrite bead should also be considered since
these allow some flexibility in optimizing the layout to meet EMC requirements.
DIGITAL
GROUND PLANE
CONNECT SPLIT GROUND
PLANES AT OR NEAR CODEC.
PIN 1
AD1881A
ISOLATION
TRENCH
ANALOG
GROUND PLANE
Figure 16. Recommended Split Ground Plane
ANALOG POWER SUPPLY
To minimize audio noise, the Codec analog power supply (AVDD) should be well decoupled and regulated. In PC systems it is rec-
ommended that the analog supply be derived from the 12 V PC power supply using a localized linear voltage regulator. Preferably,
the analog power supply should be connected to the Codec’s analog section using a ferrite bead.
REV. 0
–24–
ADI [ ADI ]
