MITSUBISHI <CONTROL / DRIVER IC>
M54640P
STEPPER MOTOR DRIVER
DESCRIPTION
The M54640P is a semiconductor IC to drive a stepper motor by
the bipolar method.
PIN CONFIGURATION (TOP VIEW)
Output
M
B
←
1
16
→
E
15
→
M
A
14
13
GND
12
11
←
V
R
10
←
C
9
Io
Comparator
reference input
Comparator input
Output current
setting
Current sensor
Output
FEATURES
q
Bipolar and constant-current drive
q
Wide current control rage (20 – 800mA)
q
Wide supply voltage drive range (10 – 40V)
q
Built in flywheel diodes
q
Current level can be changed by steps or continuously.
q
Built in a thermal shutdown circuit
One-shot-multi
T
→
2
time constant
Output power V
MM
3
supply
4
GND
5
Power supply V
CC
Output current
value setting
Output current
direction switching
I
1
6
7
V
MM
Output power
supply
M54640P
P
h
→
8
APPLICATION
Printer, FDD, HDD, Fax
Outline 16P4
FUNCTION
The M54640P drives a stepper motor by the bipolar drive method to
change the current direction of a single coil and controls the current
direction with PHASE input pin. In order to obtain higher efficiency,
the constant current drive system to control the coil current is
introduced. The current value can be selected among four levels (0
to max.) by selecting the combination of three internal comparators
by logic input. It also can be continuously changed by controlling
the reference voltage. Conversion to voltage is conducted by the
current value sensing resistor (R
s
) and the voltage is sensed with
each comparator, and then each comparator output triggers
monomulti and the current is cut for a certain time (t
OFF
) by utilizing
the inductance of the coil.
Also, diodes needed for choppering and a thermal shutdown circuit
as a countermeasure against overvoltage are built in this circuit.
BLOCK DIAGRAM
Comparator reference input
V
CC
V
R
11
6
Schmitt trigger
Cutput current
P
h
8
direction switcing
I
1
7
I
0
9
>1
>1
1
1
1
Output
M
A
Output
M
B
3 V
MM
14 Output power
supply
15
1
Output current
value setting
00
V
KH
01
10
11
V
KM
Monostable
t
OFF
= 0.69
•
R
T
C
T
Current sensor
V
KL
4
GND
5
12
13
10
C
Comparator input
2
16
E
Current sensor
T
One-shot-multi time constant
MITSUBISHI [ MITSUBISHI ELECTRIC SEMICONDUCTOR ]
