Asf/Pump Motor Driver Circuit - Epson Stylus PHOTO 2000P Service Manual

EPSON Stylus PHOTO 2000P
attached on the Gear 76 to detect paper feed amount.
The loop scale encoder sensor outputs two kinds of TTL level pulses
Phase A and Phase B to ASIC (IC8).
1/1440"
1/5760"
Phase A
Phase B
Phase A
Phase B
Lens
LED
Figure 2-20. Loop Scale Encoder Pulse
OPERATING PRINCIPLES
Forward Rotation
(Clockwise)
Backward Rotation
(Counterclockwise)
Photo
Photo
Comparators Comparators
Diodes Diodes
A
+
Phase A
A
-
B
+
B Phase B
-
Electrical Circuit Operating Principles

2.2.2.4 ASF/Pump Motor Driver Circuit

ASF/Pump motor is a PM type stepping motor. The block diagram for the
ASF/Pump motor is as shown below:
Current control signals
PFPHAA
DATA Bus PFPHAB
PFENBA
PFENBB
IC8
IC15
E05B70CD
C90A13CA
SWA2
DA0
Figure 2-21. ASF/Pump Motor Circuit Block Diagram
Revision A
+42V
OUTA ASF-A
OUTA ASF-A
PHASE1
ASF-B
OUTB
PHASE2
ASF-B
OUTB
ENABLE1
+42
ENABLE2 VBB
IC12
C69
C79
C75
LB11847
0.1U 100U
0.1U
VCC
VREF1
GND
VREF2
CN6
ASF SENSOR
-
IC22
+
SN104B00PSR
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