Service manual

Circuit Description
3-2
3-2 Circuit Operation
3-2-1 Clock
1) System Clock
• ARM946ES RISC PROCESSOR: drives PLL internally uses 120MHz and external Bus uses 60 MHz.
2) Video Clock
• Fvd =((PAPER 1SCAN LINE sending time * SCAN effective late /1SCAN LINE DOT #)*4
=(600dpi*600dpi*58.208mm/s*216mm*4)/(25.4mm*25.4mm*76.1%)=28.697MHz
•PAPER 1SCAN LINE sending time=SCAN LINE interval/DOCUMENT SPEED (58.208mm/S)
•1SCAN LINE DOT #=MAZ SCAN distance(216mm)*DOT# per 1mm
3)USB Clock
3-2-2 POWER ON/OFF RESET
1) Signal Operation
Input Signal +3.3V Power Line (VCC)
Output Signal ARM946ES nRESET and 29LU16ø
• POWER ON/OFF DETECT VCC RISING/FALLING 4.5° ≠ 4.6V
RESET TIME (Td) 1.48~1.52ms
• Td=(Ct*V sensing)/I charge (...Ct=33µF, Is=100µA)
2) TIMING CHART
Device Oscillator
Frequency 12MHz
Device Oscillator
Frequency 57.0167MHz
Device Oscillator
Frequency 48MHz
20 MCLK
MCLK
nRESET
nPWRGD
HICLK
reRESETn
RESETn
20 MCLK
5.461 ms
(65535 MCLK)
5.461 ms
(65535 MCLK)
CLK falling
15 HCLK