L6223A ST Microelectronics, Inc., L6223A Datasheet - Page 18

• Manufacturer Part Number: L6223A
• Description: Dmos Programmable High Speed Unipolar Stepper Motor Driver
• Manufacturer: ST Microelectronics, Inc.

L6223A
Figure 22: Pover output configuration.
Use of the Programming Mode
A typical application of the L6223A requires driv-
ing the motor according to Fig. 23a and Fig. 23b.
Starting from t
tor is kept in stand-by; at time t
eration period that is completed at time t
motor then is driven at a contant speed until t
when the speed is decelerated and is stopped at
t
During these events the L6223A can be pro-
grammed several times for different working
modes. The most important parameter is the cur-
rent through the windings of the stepper: at the
time t
fied, for example, as it is shown in Fig. 23b. This
behaviour allows the best motion control and, at
the same time, optimizes efficency of the power
output block of the I. C.
by programming: in fact, between t
vice can be programmed to work in Closed Loop
and to chop at half of the RC oscillator frequency
during the time t
the I. C. can be programmed to work in Open
Loop mode where the current can be fixed by the
reduction of the minimum T
defined by the discharge time of the RC oscillator.
Of course in this way the current can be modified
by Supply Voltage changes; the same is not pos-
sible in Closed Loop operation where the device,
in order to keep the windings current constant,
modifies the T
at high V
is driven at a constant speed (t
current and high Supply Voltage, it could become
necessary to program the lower chopping fre-
18/33
5
But this is not the best in terms of performances
= t
0
0
for a new standby period.
; t
1
S
; t
. This is the reason why when the motor
2
; t
0
ON
3
= t
3
and t
time: wide at low V
5
to t
and continuing until t
4
4
. In the stand-by condition
the current can be modi-
ON
time (75% or 50%)
1
3
begins an accel-
to t
1
and t
S
4
) with small
and narrow
1
5
the mo-
the de-
3
. The
4
,
quency to allow a suitable T
the current of the windings would go out of con-
trol.
The motion profile, shown in Fig. 23a can be ob-
tained when preferred, with only two program
changes actuated while the motor is in stand-by.
The current becomes as shown in Fig. 23c. The
device can be programmed at t
55% (stand-by) and at t
the actuations, the DA/CLEV is kept high to allow
the program change, while, by keeping it to zero
during t
ically select as 100% (Fig. 23d). During t
current is reduced according to the percentage
programmed at the time t
Power dissipation (Simplified method of calcula-
tion).
Here below the Full Step Operating Mode is con-
sidered; in addition, the following working condi-
tions have been taken up:
1) Constant speed rotation of the driven unipolar
stepper Motor.
Figure 23: a,b) Speed profile and motor current
control change for the best efficency of the I.C.
c,d) Current control change by using DA/CLEV
input only, during the stand-by period.
1
- t
3
and t
4
- t
1
5
, the current is automat-
1
for I
.
motor
ON
0
width otherwise
= 70%: for both
= t
5
for I
3
- t
motor
4
the
a
b
c
d
=