— 7 —
Filter Block
From DAC
To power amplifier
Name
Voltage
For operation of
VDD
+5 V
CPU, Reset IC, Sound source ROM, LED Latches
DVDD
+5 V
Power jack, Photocoupler
AVDD
+5V
DAC, Filter
LVDD
+5 V
LED Drivers
VCC
+9 V
Power amplifier, Pilot lamp
VC
+9 V
Power amplifier
Pin No.
Terminal
In/Out
Function
1
Power GND
In
Ground (0V) source
2
Ch1 B.S.
Terminal for a bootstrap capacitor
3
Ch1 OUT
Out
Channel 1 output
4
VCC
In
+9V source
5
Ch1 N.F.
In
Negative feedback input
6
Ch1 IN
In
Channel 1 input
7
D.C.
Terminal for a decoupling capacitor
8
Pre GND
In
Ground (0V) source
9
Stand by
In
Power control signal input. 0 V: Off, +9 V: On
10
Ch2 IN
In
Channel 2 input
11
Ch2 N.F.
In
Negative feedback input
12
Ch2 OUT
Out
Channel 2 output
13
Ch2 B.S.
Terminal for a bootstrap capacitor
14
NC
Not used
POWER SUPPLY CIRCUIT
The power supply circuit generates six voltages as shown in the following table. VDD voltage is always
generated. The others are controlled by APO signal from the CPU.
FILTER BLOCK
Since the sound signals from the DAC are stepped waveforms, the filter block is added to smooth the
waveforms.
POWER AMPLIFIER (IC102: LA4598)
The power amplifier is a two-channel amplifier with standby switch.
The following table shows the pin function of IC102.
