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MITSUBISHI
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 MB 1 One-shot-multi T 2 time constant Output power VMM 3 supply 4 GND 5 Power supply VCC Output current value setting Output current direction switching I1 6 7 16 E 15 MA 14 13 GND 12 11 VR 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
VMM Output power supply
M54640P
Ph 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 (Rs) and the voltage is sensed with
each comparator, and then each comparator output triggers monomulti and the current is cut for a certain time (tOFF) 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 VCC VR 11 6 Schmitt trigger Cutput current Ph 8 direction switcing I1 7 I0 9 >1 >1 1 1 1 Output MA Output MB 3 VMM 14 Output power supply
15
1
Output current value setting
00 VKH
01
10
11
VKM Monostable tOFF = 0.69 * RT CT Current sensor
VKL 4 GND 5 12 13 10 C Comparator input 2
16 E Current sensor
T One-shot-multi time constant
MITSUBISHI
M54640P
STEPPER MOTOR DRIVER
ABSOLUTE MAXIMUM RATINGS (Ta=25C, unless otherwise noted)
Symbol VCC VMM VL VC VR IL IC IMM Pd Topr Tstg Parameter Supply voltage Output supply voltage Logic input voltage Analog input voltage Comparative input voltage Logic input current Analog input current Output supply current Power dissipation Operating temperature Storage temperature Conditions Ratings -0.3 - 7 -0.3 - 45 -0.3 - 6 -0.3 - VCC -0.3 - 15 -10 -10 1000 1.92 -20 - 75 -55 - 125 Unit V V V V V mA mA mA W C C
Mounted on a board
Note. Every voltage value is measured when the voltage at GND pin is 0V. The maximum and the minimum of each voltage value are shown in absolute values. Regarding current directions, inflow current is shown in a positive value and outflow current is shown in a negative value. The maximum and the minimum of each current value are shown in absolute values.
RECOMMENDED OPERATING CONDITIONS (Ta=25C, unless otherwise noted)
Symbol VCC VMM IO tPLH tPHL TON Parameter Supply voltage Output supply voltage Output current Logic input rise time Logic input fall time Thermal shutdown temperature Min. 4.75 10 20 Limits Typ. 5 Max. 5.25 40 800 2 2 Unit V V mA s s C
175
ELECTRICAL CHARACTERISTICS (VCC=5V, Ta=25C, unless otherwise noted)
Symbol VIH VIL VCH VCM VCL ICO IOFF Vsat tOFF td ICC IIH IIL Parameter Logic input voltage "H" "L" VCC=5V VR=5V, I0=I1=0 VR=5V, I0=1,I1=0 VR=5V, I0=0, I1=1 I0=I1=1(Ta=25C) The voltage at the sensing resistor is not included. IO=500mA VMM=10V, tON5s Ta=25C, dVK/dt50mV/s VCC=5V VI=2.4V VI=0.4V 25 30 1.6 Test conditions Min. 2.0 0 400 240 75 -20 Limits Typ. Max. VCC 0.8 450 280 100 20 100 4.0 35 2.0 25 20 -0.4 Unit V
Comparator threshold Comparator input current Output cutoff current Saturation voltage Cutoff time Turnoff delay Supply current Logic input current "H" "L"
430 260 90
mV A A V s s mA A mA
MITSUBISHI
M54640P
STEPPER MOTOR DRIVER
SWITCHING CHARACTERISTICS Test circuit Switching waveforms
VMA - VMB or VMB - VMA tOFF = 0.69RTCT 1 CT 1 MB 2T 3 VMM RT 4 GND 5 6 VCC 7 I1 8 Phase GND 12 VR 11 C 10 I0 9 CC VCH VCM VCL 13 RC td E 16 MA 15 VMM 14 CV RS VCC 1/2
tON
tOFF
RS :1 RC : 1k RT : 56k CC : 820pF CT : 820pF CV : 47F
APPLICATION DESCRIPTION
* PHASE INPUT Phase input decides the output mode. PHASE H L * I0, I1 I0 and I1 fixed based on the comparison voltage VR decide the output current level. The current level can be continuously changed by changing the voltage at VR continuously. I0 H L H L I1 H H L L Current level 0 Low Average High MA H L MB L H
* Current sensor When the voltage fall at the current sensing resistor and the selected current level becomes of the same level, the comparator triggers the monostable. Then, the output stage is cut off for a certain time (tOFF). During this cutoff time, the current volume decreases slightly and falls short of the comparison level. After the cutoff time (tOFF), the output stage is in ON state again. This operation is repeated. * Single pulse generator At the comparator output rise edge, the monostable is triggered. The pulse width of the monostable at the external timing Rt and Ct is as follows. tOFF = 0.69 x RtCt Retrigger during tOFF is neglected. * Analog control The output current level can be continuously changed by changing the voltage at VR or the feedback voltage to the comparator.
MITSUBISHI
M54640P
STEPPER MOTOR DRIVER
TIMING CHART
2-phase excitation
Phase A Phase B
I0, 1 = (A) = 0 I0, 1 = (B) = 0
1-2-phase excitation Phase A Phase B
I0, 1 = (A)
I0, 1 = (B)
Microstep (divided into six)
Phase A
Phase B
I0 (A) I1 (A)
I0 (B)
I1 (B)
MITSUBISHI
M54640P
STEPPER MOTOR DRIVER
TYPICAL CHARACTERISTICS (Absolute maximum ratings)
Safety operating temperature
1.0 A : Recommended 0.8 Output current Io (A) B B : Schottky diodes should be externally connected between output pins and power supply pins. 0.6 C : Schottky diodes should be externally instaalled between output pins and power supply pins and between output pins and GND pin. 0.4 A 0.2 C
0
0
10
20
30
40 45
50
Output VMM (V)
Thermal derating
10.0 j-c = 10C/W Allowable power dissipation (W) 8.0 A : Mounted on a 25cm2 glass epoxy board which is coated with copper on one side. c-a = 45C/W B : 10cm2 aluminum heat sink (1t) is used. c-a = 25C/W C : 100cm2 aluminum heat sink (1t) is used. c-a = 10C/W Tj(max) = 150C
6.0
C
4.0 B 2.0 A
0
0
25
50 Ambient (C)
75
100
MITSUBISHI
M54640P
STEPPER MOTOR DRIVER
APPLICATION EXAMPLE
1 820pF 1k 5V
16 15 14 13 12
11 10
9
M54640P
1 2 3 4 5 6 7 8
820pF 56k 1 1k 820pF
Phase A I0A I1A
24V 47F
16 15 14 13 12 11 10 Stepper motor
9
M54640P
1 2 3 4 5 6 7 8 Phase B I0B 56k I1B
820pF
PRECAUTIONS FOR USE
(1) When the whole output current changes by a large margin (for example, when overheat protection operation causes intermittent flow of output current), the supply voltage may undergo a change. Therefore, selection and wiring of power supply should be conducted cautiously to avoid such a situation that the supply voltage exceeds the absolute maximum ratings. (2) When the supply voltage changes by a large margin, the operation of this IC may become unstable. In this case, the change of supply voltage can be controlled by connecting a capacitor at the point near to IC pin between Vcc pin and GND pin. (See above application example.)
(3) Thermal shutdown function * The state of thermal shutdown operation may differ according to the way of wiring within a board. Therefore, sufficient board evaluation should be conducted before use. When the board is changed, operation on the replacing board should be evaluated. * The circuit board on which this IC is mounted is designed to realize low impedance between power supply and output pin. Therefore, it is desirable to take a safe measure such as fixing a fuse to avoid such a situation that the board is damaged by a fire when output pin is internally short-circuited by excessively applied surge voltage by accident.

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