CMX649 CML Microcircuits, CMX649 Datasheet - Page 5

• Manufacturer Part Number: CMX649
• Description: ADM Codec
• Manufacturer: CML Microcircuits

ADM Codec
4.
Notes:
2003 CML Microsystems Plc
1. C1 - C4 and R1 - R4 set the microphone amplifier gain and frequency response. The values
2. DC blocking capacitor for driving a speaker from an external speaker amplifier. The value shown
3. V
4. Bias decoupling capacitor.
5. A 4.096MHz Xtal/Clock input will yield exactly 16kbps/32kbps/64kbps internally generated data
6. To achieve good noise performance, V
C6
External Components
shown set the gain to unity and the low and high –3 dB frequency rolloff points to approximately
150Hz and 15kHz respectively.
is based on a 32
approximately 150Hz.
clock rates.
from extraneous in-band signals are very important. It is recommended that the printed circuit
board is laid out with a ground plane in the CMX649 area to provide a low impedance connection
between the V
DD
MIC
R1, R2
R3, R4
C1, C3
C2, C4
decoupling capacitor.
C7
C2
C4
R2
R4
SS
C5
Note 1
Note 1
Note 1
Note 1
R3
pin and the V
impedance speaker where the highpass rolloff frequency is set to
Figure 2 Recommended External Components
C1
R1
C3
100 pF
0.01 F
100k
100k
DECODE VAD
ENCODE VAD
AUDIO OUT
DD
MIC OUT
VBIAS
STRB
and V
MIC+
MIC-
VDD
VSS
10%
10%
20%
20%
DD
BIAS
10
1
2
3
4
5
6
7
8
9
and V
5
decoupling capacitors.
BIAS
CMX649E3
C5
C6
C7
X1
decoupling and protection of the signal path
Note 2
Note 3
Note 4
Note 5
20
19
18
17
16
15
14
13
12
11
33.0 F
1.0 F
1.0 F
4.096MHz
TX DATA
TX CLK
CSN
SCLK
CMD
RPLY
IRQN
XTAL/CLK
RX CLK
RX DATA
20%
20%
20%
INTERFACE
X1
CMX649
D/649/2
C