Filter
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The following table shows the pin functions of the key touch LSI.
Pin No. Terminal In/Out Function
1 REQB Out Interrupt request. Not used.
2, 3 FI10, SI10 In Key input signal
4 VCC In +5V source
5 CRDB In Read enable signal
6 CWRB In Write enable signal
7 CCBB In Chip select signal
8, 9 T, STBY In Not used. Connected to +5V.
10 RESB In Reset signal
11 W In Not used. Connected to +5V.
12 CKI In 10 MHz clock input
13, 14 TMD, TST In Not used. Connected to ground.
15 CKO Out Not used.
16 GND In Ground (0V) source
17 XIN In Not used. Connected to ground.
18 XOUT Out Not used.
19 TRES In Not used. Connected to ground.
20 ~ 23, 25 ~ 28 CD0 ~ CD7 In/Out Data bus
24 GND In Ground (0V) source
29 ~ 31 CR0 ~ CR2 In Address bus
32 VCC In +5V source
33 ~ 39, 41 ~ 43
53 ~ 55, 57 ~ 63
FI0 ~ FI9,
SI0 ~ SI9
In Key input signal
40 VCC In +5V source
44 ~ 47, 49 ~ 52 KC0 ~ KC7 Out Key scan signal
48, 56 GND In Ground (0V) source
64 VCC In +5V source
Filter Block
Since the sound signals from the DAC are stepped waveforms, the filter block is added to smooth the
waveforms.
AVDD
1K
1K 1K
C182(H)
C152(H)
AG
AG
1K
AG
To main volume
-
+
M5218APR
10V22µ
C104(H)
2SC1740SQ
10K
AVEE
10V22µ
From the DAC