CS3717A Datasheet, PDF (5/8 Pages) Cherry Semiconductor Corporation – 1A H-Bridge Stepper Motor Driver

Application Information: continued
For rotation in the other direction the sequence must be
reversed.
The torque of each step is constant in full step operation.
Half step operation
Power is applied alternately to one winding then both
according to the sequence:
AB®B®AB®A®AB®B®AB®A etc.
Like full step this can be done at any current level; the
torque is not constant but is lower when only one winding
is energized.
A coil is turned off by setting IN0 and IN1 both high.
Quarter step operation
It is preferable to realize the quarter step operation at full
power otherwise the steps will be of very irregular size.
The extra quarter steps are added to the half step
sequence by putting one coil on half current according to
the sequence.
AB®^A2 B®B®^A2 B®AB®AB2®A etc.
Motor selection
As the CS3717A provides constant current drive with a
switching operation, care must be taken to select stepper
motors with low hysteresis losses to prevent motor over-
heating.
L-C filter
To reduce EMI and chopping losses in the motor, a low
pass L-C filter can be inserted across the outputs of the
CS3717A as shown in the following diagram.
Input and Output Sequences for Half Step and Full Step Operation
OUTA
CS3717A
OUTB
L@
1
10
L_M
L
C
MOTOR
WINDING
(L_M, R_M)
C @ ^{4 ¥ 1010}
L
STAND BY WITH
HOLDING TORQUE
1M = 80mA
1
IN0_A
IN1_A
HALF STEP MOTOR DRIVE
1M = 250mA
2345678
FULL STEP MOTOR DRIVE
1M = 500mA
IN
DIRECTION_A
DIRECTION_B
IN0_B
IN1_B
500 mA
OUT
I_MA
- 500 mA
500 mA
I_MB
- 500 mA
5