8-21
6. CPU CIRCUIT
1) CPU
IC801: 8 bit CPU / CMOS IC
IC802: EEPROM / CMOS IC
IC571: I/O Expander
This system has the following functions.
Frequency Counter
I
2
C BUS control
fH band
Degaussing Control
DAC control (see 2. DC Control Circuit)
PMS control (see 3. Power Management system (PMS) Circuit )
OSD control (see 5. User Control Operation)
a. Frequency Counter
IC801 counts Horizontal frequency by event counter, Vertical frequency by interval timer. Horizontal
sync is negative input to IC801 pin 4. Vertical sync is positive input to IC801 pin 36.
Sync range
Horizontal 31.0 - 115.0 kHz
Vertical 55.0 - 160 Hz
If Horizontal frequency is less than 1 kHz or Vertical frequency is less than 10 Hz, IC801 judges “NO
PULSE”. And IC801 enters to “PMS MODE”.
b. I
2
C BUS control
CPU (IC801) controls the following ICs through I
2
C BUS.
DAC IC751(M62393FP)、IC532(M62392FP)
PREAMP IC711(M52742ASP)
E
2
PROM IC802(24LC08,M24C08) 、IC8A1(24LCS21A)
I/O EXPANDER IC571(M62320FP)
OSC IC(DSP) IC501(HE6-0092)
OSD IC IC791(M35070-050FP)
SUB CPU IC851(MC68HC705BD32FU)
AUTO SIZE IC IC8M1(BU6483K)
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