Epson SQ-B50/2550 Technical Manual page 117

REV.-A
2.4.2.4 Drive Circuit Control
The drive circuit is shown in Figure 2-53. The drive circuit consists of transistors with corrector follower
bridge connection. The motor current signal to the current motor is provided as it is pre-driven at each
port of the DCU, NPN 1,2 and PNP 1,2. Here the term "pre-drive" or "pre-driven" means overcurrent
control. A more detailed description will be provided later.
Table 2-5 shows a variety of current signal combinations given at each port.
Table 2-5. Current Signals
Motor Operation Rotation
PNP1 PNP2 NPN1 NPN2
Contents
CW LOW HIGH HIGH
Cu rrent flow from CM+ to
LOW
CM~
Acceleration/
constant velocity
Current flow from
CM~
to
CCW HIGH LOW LOW HIGH
CM+
Hold LOW LOW HIGH HIGH
CM + and CM - have the same
-
electrical potential.
CW HIGH
LOW
LOW HIGH
Reverse braking against clock-
wise rotation.
Reverse braking
CCW LOW HIGH HIGH LOW
Reverse braking against coun-
terclockwise rotation.
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