Epson LQ-2550 Technical Manual page 131

Reference Voltage Generation Circuit
Figure 2-80 shows the reference voltage generation circuit and Table 2-53 shows the relationship
between each POT terminal state of the MCU and carriage speed. This circuit changes the voltage
applied to the RS terminal of the CR motor driver IC S17304 (7C) using the combination of R55, R56,
The current limit is raised as the carriage speed increases by changing the voltage applied to the RX
terminal.
Table 2-53. MCU POT Terminal States and Carriage Speed
RX Terminal
Voltage
High
Low
(4 B)
5
1
Figure 2-80. Reference Voltage Generation Circuit
H H H
L H H
H H
L
H H L
S 1 - 7 3 0 4
2 0 Rx (7C)
\
G7
CR Motor Coil
Mode
Current [A/Coil]
Driving
1.0 * 0.1
Holding 0.25
2-85
REV.-A
Carriage Speed
Voltage
Speed O or 1
Speed 2 or 3
Speed 4
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