*
REV.-A
Gate Array (IC7A: E05A16GA)
This gate array
(IC7A)
outputs the carriage speed control signal
(PCO
and
PC3)
to the 4-phase stepper
motor drive
IC
(IC2A:
STK6722HZ), under the control of the CPU. The carriage speed is controlled
by combining the reference voltage for the 4-phase stepper motor drive
IC
(IC2A)
with
PCO
and
PC3.
Figure 2-35 shows the block diagram of the gate array
(IC7A)
operation.
CPU
7810HG
(4B)
PD7
I
PDO
m
G
GA(E05A
15HA)
+5V
STK6722
(3A)
DB7
I
DBO
Pco
PD 1
7
R97
3.OIK
(2A)
VCC2
Vref
PD
Figure 2-35.
GA (E05A16GA) Operation Diagram
This gate array also performs another function. When a hardware error (except a paper end) is
detected in the printer, the gate array outputs the power down signal (PD 1 ) to the 4-phase stepper
motor drive IC
(IC2A)
and shuts off the +36 VDC, so that damage to the circuit can be minimized.
2-43
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