CHAPTER 2
2 - 23
COPYRIGHT
2000 CANON INC. CANOSCAN N650U/N656U/N1220U REV.0 JUNE 2000 PRINTED IN JAPAN (IMPRIME AU JAPON)
V. POWER SUPPLY
The scanner draws its power +5V from USB interface. +5V is used for the digital circuit in
the main PCB.
Power supply to the analog circuit is ON/OFF controlled by the gate array. Drive motor,
contact image sensor, and analog circuit are supplied with power as necessary. 5.5V step up
circuit in the main PCB is used for the analog circuit and for driving the contact image sensor.
Figure 2-24
+5V
Main PCB
Drive motor
Contact image
sensor
Host comuter
USB
port
Gate
array
5.5V step up circuit
LED
Digital circuit
Analog circuit
5.0V reference voltage