Application Information: continued
For rotation in the other direction the sequence must be
reversed.
The extra quarter steps are added to the half step
sequence by putting one coil on half current according to
the sequence.
The torque of each step is constant in full step operation.
A
A
B
AB® B®B® B®AB®A ®A etc.
2
2
2
Half step operation
Power is applied alternately to one winding then both
according to the sequence:
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.
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.
L-C filter
A coil is turned off by setting IN0 and IN1 both high.
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.
Quarter step operation
It is preferable to realize the quarter step operation at full
power otherwise the steps will be of very irregular size.
Input and Output Sequences for Half Step and Full Step Operation
L
OUTA
MOTOR
WINDING
(LM, RM)
CS3717A
OUTB
C
4 ¥1010
1
10
L @
L M
C @
L
STAND BY WITH
HOLDING TORQUE
1M = 80mA
HALF STEP MOTOR DRIVE
1M = 250mA
FULL STEP MOTOR DRIVE
1M = 500mA
1
2
3
4
5
6
7
8
IN0
IN1
A
A
DIRECTIONA
DIRECTIONB
IN
IN0B
IN1B
500 mA
IMA
- 500 mA
500 mA
OUT
IMB
- 500 mA
5
CHERRY [ CHERRY SEMICONDUCTOR CORPORATION ]
