M54676E Просмотр технического описания (PDF) - MITSUBISHI ELECTRIC
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M54676E Datasheet PDF : 5 Pages
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MITSUBISHI <CONTROL / DRIVER IC>
M54676P
2-PHASE STEPPER MOTOR DRIVER
FUNCTION DESCRIPTION
• Phase input
Phase input decides the output mode.
PhaseA
(PhaseB)
Phase ∗A
(Phase ∗B)
OutA
(OutB)
Out ∗A
(Out ∗B)
H
L
H
L
L
H
L
H
H
H
Z
Z
L
L
Z
Z
*Z: High impedance
In order to prevent through current caused by turning on output
transistors simultaneously at PhaseA=Phase ∗A=“H”, both phase
inputs go in the high mode simultaneously and output goes in the
high impedance state.
Furthermore, as a countermeasure against output through current
at the time of phase switching, a delay time (3us) to turn on the
motor drive output when phase input goes in high state is set
within the IC.
• Standby circuit
When Vcc5 voltage is 0.8V or below or open, the IC goes in the
standby state. In the standby state, leak current does not flow into
VM power supply, logic input pins (Phase input), and analog input
pins (Vref input and Sense input). Never forget to set VM power
supply to be the maximum voltage level among all voltages
applied to the IC in the standby state. (As for details, refer to
“PRECAUTIONS FOR USE.”)
• Thermal shutdown (TSD) circuit
This IC has the thermal shutdown function to protect itself against
damage by a fire when chip temperature rises abnormally.
• Flywheel diode
Because flywheel diodes for chopper current control are built in
this IC, it is not necessary to connect external flywheel diodes.
Also, by connecting schottky diodes with low VF externally, it is
possible to reduce thermal loss.
• Vref input (Comparative voltage)
Chopper current (motor current) is controlled by changing Vref
input voltage.
By inputting SIN wave to VrefA and COS wave to VrefB, A-phase
coil current and B-phase coil current change continuously and the
microstep drive of a stepper motor is performed.
• Current comparator
Sense pin voltage (voltage fall at current sensing resistor = motor
current) and Vref input proportional voltage (Vref/10) are
compared.
Sense pin voltage < Vref/10: the comparator output is in high
state and output transistors are turned on. Then, current flows into
the motor.
Sense pin voltage > Vref/10: the comparator output is in low state
and output transistors are turned off. Current does not flow into
the motor.
The above operation is repeated to control the current of the
motor.
• Vref comparator
Vref input proportional voltage {(Vref/10)} and internal reference
voltage are compared. If Vref input voltage is 0.3V or lower,
output transistors are turned off and motor current stops
regardless of Phase input and Sense input.
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