M41T00AUD
Audio section operation
29/44
Figure 16. Audio section diagram
BPF
100Hz - 8kHz
256Hz
512Hz
256/512
SELEC
T
T
ONE
ON/OFF
F
rom inter
nal
RTC timing chain
register bits
Sum m
ultiple audio
signals through e
xter
nal
resistors
, b
ut single input
Switch 256/512 signal
in place of audio signal
GAIN, 3dB steps
,
–33dB to +12dB
(4-bit register)
300mW
@ 8
Ω
V
DD
V
DD
2
V
DD
2
V
BIAS
A
OUT+
A
OUT–
AIN
Lo
w end of band pass filter is actually
implemented b
y
b
loc
king capacitor at
input pin.
Only the high end (lo
w-pass
section) is implemented at this point in the
audio section.
R2 10k
Ω
FBK
R1 20k
Ω
R1
x 20k
Ω
R2 should
be a minim
um
of 10kOhm
Set R1
’s
to
2x
R2 f
or unity gain
1
μ
F
ai13328
0.1
μ
F
S
IN
