L6223 Datasheet, PDF (26/33 Pages) STMicroelectronics – DMOS PROGRAMMABLE HIGH SPEED UNIPOLAR STEPPER MOTOR DRIVER

L6223
Matching the L6223 with the motor.
For the correct design of the application the fol-
lowing notes must be considered.
* For low motor resistance and high supply volt-
age the L6223 minimum duty cycle may limit
the minimum current at a value higher than re-
quested.
In this case we suggest to reduce the window
protection time changing the RC oscillator net-
work. (See Fig. 21a and External RC Network).
* Only in single device application, for very low
motor resistance, a large current imbalance
may affect the correct motor rotation. Motor re-
sistance value higher than 7 Ohm are generally
recommended for 35V Power Supply.
* The correct motor winding execution is very im-
portant for the motor and the L6223 efficiency.
A simple test is the measurement of the stray
inductance between the central tap and the
ends shorted together of each winding. Theo-
retically the inductance would be zero; values
higher than 50µH may show poor motor quality.
Computer Aided Development Board
An improvement in the application development
and in system debugging can be obtained by
means of the Personal Computer.
Interfacing the appliction with the PC, the motor
can be driven directly by this in real time opera-
tion. This permits the testing in very short time
and a lot of different motion configurations, during
application debugging and optimization. More-
over, by paralleling more application boards, an
efficient reliability test can be implemented.
The development board designed to drive L6223
in Single and Dual Device configuration is shown
in Fig. 32a-b. Fig. 33 is the corresponding electri-
cal circuit. On the board are mounted three
L6223: two for the Dual Device configuration and
one for the Single Device. The three connectors
J1, J2, J3 allow the application board to be inter-
faced with the PC and to be paralleled with an-
other one. The remaining connectors provide the
interface with the motor and the power and logic
supply. The ground area has been sized to act as
heatsink (35 micron thickness). When the copper
area is not sufficient to dissipate the heat an ex-
ternal heatsink is required.
26/33