Epson SQ-B50/2550 Technical Manual page 96

REV.-A
2.4.1.3 Paper Feed Motor Drive Circuit
This circuit uses the SLA7020M to drive the paper feed motor at a constant speed. Refere to the
Appendix for the SEIMA Board Circuit Diagram (location 2-3/I-J).
The SLA7020M is a hybrid IC that uses a constant-current driven stepping motor. The value of the
current is determined by the value of the external voltage input. The IC is divided into two phases, AB
(AA) and CD (BB), that use the same circuit.
Reference
Current
Motor Main
Current
rz
RC to Protect
Abnormal Chopper
Operation
Vb
Vcc
f""
Auxiliary Excitation
Motor
RC to Set
RZ8
Current Current
~
Chopper OFF Time
C7/C8
J;:
T,=- _ _
J~s
n
IN OUT
-
OUT
r-------------
- - - - - - - - - - - - - - -
- -
- -
f' ' '
I
R30
REF
Excitation Current
C9/C 10 ,..
I
Current Peak _ Chopper OFF
Signal Transfer
- Current Control and
_ Circuit
Counter Electromotive
I
Detection
Time Control
D Force Cancel Circuit
:r
Circuit
Circuit
f---
L ________________
GNO _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
- - - - -
Rs
;.1.
oo~ ~
Rs
Db T-
T
R esi st or for
Current Detection
Figure 2-28. SLA 7020M Internal Block Diagram
2-28