Casio CTK-220L Manual De Usuario

— 5 —

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

Since the sound signal from the CPU is a stepped waveform, the filter block is added to smooth the waveform.

The power amplifier is a two-channel amplifier with standby switch.
The following table shows the pin function of IC301.

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