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MITSUBISHI
M54676P
2-PHASE STEPPER MOTOR DRIVER
DESCRIPTION
The M54676P is a semiconductor IC to drive a bipolar stepper motor by the micro step method by changing the coil current of the motor continuously.
PIN CONFIGURATION (TOP VIEW)
OutA Out A SG A Sense A GND GND Vref A Phase A Phase A 1 2 3 4 5 6 7 8 9 20 VM 19 OutB 18 Out B 17 SG B 16 GND 15 GND 14 Sense B 13 VrefB 12 PhaseB 11 Phase B
FEATURES
qHighly-accurate micro step drive by chopping sink output transistor and source output transistor simultaneously qBipolar and constant current drive qBuilt in a thermal shutdown circuit and standby circuits qBuilt in flywheel diodes
M54676P
APPLICATION
Office automation equipment such as printer and FAX
Vcc5 10
Outline 20P4
FUNCTION
The M54676P can drive a stepper motor by the 2-phase bipolar method and also controls the coil current. Furthermore, it controls the direction of the coil current by Ph input and the coil current value by Vref pin. Because two control circuits are built in this IC, a stepper motor can be driven with a single IC by the 2-phase bipolar method.
BLOCK DIAGRAM
OUT A OUT A VrefB 13 Vcc5 10 1K 20K 6K
Internal bias
VrefA 7
20
VM
1
2
Vref A Amp
+ -
Vref 2 comparator
+ -
9K
0.2V
+ -
1K Current comparator
Vref B Amp
+ -
Vref 2 comparator
+ -
3
SGA
19 OUT B 18 OUT B
9K
0.2V Current comparator
+ -
TSD
4 14 SenseA SenseB
8 PhaseA
9 Phase A
11 12 PhaseB Phase B
16 15 6 GND
5
17 SGB
MITSUBISHI
M54676P
2-PHASE STEPPER MOTOR DRIVER
ABSOLUTE MAXIMUM RATINGS (Ta= 25C, unless otherwise noted)
Symbol VM Vcc5 Iout Vanalg Vlogic Pt K Tj Ta Tstg Parameter Supply voltage 1 Supply voltage 2 Maximum output current Analog input voltage Logic input voltage Allowable loss Thermal derating Junction temperature Operating temperature Storage temperature Conditions Pin Pin
20 10
Pins 4 7 13 and 14 Pins 8 9 11 and 12 100mm x 100mm, t=1.6mm Glass epoxy board ( ja=50C/W ) ditto
Ratings Vcc5 - 20 -0.3 - 7 500 -0.3 - 7 -0.3 - 7 2.5 20.0 150 0 - 75 -20 - 125
Unit V V mA V V W mW/C C C C
ELECTRICAL CHARACTERISTICS (DC CHARACTERISTICS) (Ta=25C, VM=12V, Vcc=5V, unless otherwise noted)
Symbol Vsat Vcc5 H Vcc5 L Icc10 Icc20 Istby Ivref Vref Vsense Vcoff Vin H Vin L Iin H Iin L Isense Ioff Parameter Output saturation voltage Vcc5 input voltage H Vcc5 input voltage L Circuit current VM reactive current Standby VM current Vref input bias current Vref amplifier input voltage range Sense pin threshold voltage Comparator OFF reference voltage Logic input voltage H Logic input voltage L Logic input current H Logic input current L Sense input current Output cutoff current Pins Pins Pins Pins Pins Pins
8 8 8 8 4 1 9 9 9 9 14 2
Test conditions Load=350mA (total) Pin 10 (Vcc5) voltage (Operating mode) Pin 10 (Vcc5) voltage (Standby mode) Pin 10 current (Vcc5=5V) Pin 20 current (VM=12V, Vcc5=5V) Pin 20 current (VM=12V, Vcc5=0V) Vref=0V See Vref-Vsense characteristics 12-4 Vcoff : Comparator OFF reference voltage Sense pin voltage when output changes at Vref=2.5V
Min. 4.5 0
Limits Typ. 1.35 5.0 38 6 0 -10
Max. 1.8 5.5 0.8 57 20 100 Vcc5 -1.5
Unit V V V mA mA A nA V mV V V V A A A A
-200 Vcc off 230 0.1
250 0.2
270 0.3 Vcc5 0.8 10
and and 11 and 11 and =0V 11 and
11 11
12 12 12 12
2.0 0 =5V =0V -20 -15 0 -7 -2 0
12
100
ELECTRICAL CHARACTERISTICS (AC CHARACTERISTICS) (Ta=25C, VM=12V, Vcc=5V, unless otherwise noted)
Symbol Tdon Tdoff Tdamp Tdph Parameter Output turn-on delay Output turn-off delay Vref amplifier response time Phase delay time Test conditions
Time required to turn on output when Sense pin voltage is decreased from 0.5V to 0V at Vref=2.5V Time required to turn off output when Sense pin voltage is increased from 0V to 0.5V at Vref=2.5V Time required to turn on output when Vref pin voltage is increased from 0V to 3.5V at Sense=0.25V
Time required to turn on output when Phase pin voltage is increased from 0V to 5V at Vref=2.5V and Sense=0V
Min.
Limits Typ. 0.3 1.5 10
Max. 1.0 2.5 30 12
Unit S S S S
Tdoff Tdon
3
MITSUBISHI
M54676P
2-PHASE STEPPER MOTOR DRIVER
FUNCTION DESCRIPTION
* Phase input Phase input decides the output mode. Phase A (Phase B) L H H L Out A (Out B) L H Z Z
* 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.
PhaseA (PhaseB) H L H L
OutA (OutB) H 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. * 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.
MITSUBISHI
M54676P
2-PHASE STEPPER MOTOR DRIVER
APPLICATION EXAMPLE
A
Stepper motor
12V 1 OutA Out A VM 20
B
2 RS1 3 SR1 4 SC1 5
OutB Out B
19
SGA
18 RS2
SenseA
SGB
17
GND
GND
16 SR2
6
GND
GND
15 SC2
D/A input
7
VrefA
SenseB
14
8
PhaseA Phase A
VrefB
13
D/A input
9
PhaseB
12
5V
10
VCC5
Phase B
11
RS1,RS2 = 0.5 SR1,SR2 = 1.6K SC1,SC2 = 0.1F
MITSUBISHI
M54676P
2-PHASE STEPPER MOTOR DRIVER
PRECAUTIONS FOR USE Sequence of supply voltage (VM and Vcc5) and logic input voltage
The VM voltage should be the maximum voltage among all voltages applied to this IC. If no voltage is applied to VM and 5V voltage is applied to Vcc5 pin and logic input pin, leak current flows from Vcc5 pin and logic input pin to VM through a surge protection diode. Logic input 5V,0V 5V,0V
Wiring on the board
Current is controlled by flowing output current to the current sensing resistor (1 ohmlevel) to measure the voltage fall. The output current performs the chopping operation at high speed. Therefore, wiring to flow current and to connect the highimpedance input pin (Vref) should be conducted carefully not to cause a cross talk.
VM 12V 12V 0V (Open)
Vcc5 5V 0V (Open) 5V
Mode Normal operation mode Standby mode (No current flows to logic input pin and Vcc pin.) Leak current flows from Vcc5 pin and Prohibited logic input pin to VM pin.
5V,0V
Sequence
After the VM voltage rises, set the Vcc5 power supply voltage and logic input voltage. Similarly, after Vcc5 supply voltage and logic input voltage rise, raise the VM supply voltage.
Time
VM
Vcc5 and logic input
Thermal shutdown function
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 excessive surge voltage applied externally by accident (or when the TSD function is damaged).
Thermal loss
In case that conditions for use (regarding supply voltage and output current) or a board used is changed, sufficient thermal evaluation should be conducted and design should be worked out to leave a margin for thermal loss. The higher the chopping frequency is, the larger switching loss within the IC becomes.

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