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LG
LVDD
CPU
LSI1
MSM6755B-13
LX0 ~ LX7
LY1 ~ LY7
Q1 ~ Q4
Q5 ~ Q8
Q2 ~ Q4
La ~ Lg
(Common)
(Segment)
MWEB
LED
Latch
IC3
7-segment LED Keyboard LEDs
LED
Latch
IC2
MD0 ~ MD3
MD4 ~ MD7
MA0
Amp.
IC301
Filter Block
Q305
CPU
LSI1
FILTER BLOCK
Since the sound signal from the CPU is a stepped waveform, the filter block is added to smooth the waveform.
POWER AMPLIFIER (IC301: LA4598)
The power amplifier is a two-channel amplifier with standby switch.
The following table shows the pin function of IC301.
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
LED DRIVING