Hi everyone, I hope you all can give me your comments and advices on this
project I am working on.
I am currently working on a motor driving circuit controlled by a
microcontroller. The schematic in jpg file can be found in
http://www34.brinkster.com/marklimkk/sch.jpg

Here's a bit more detail about the circuit:

The purpose of this circuit is to control the movement of a crane that can
move up/down/left/right. As such, 2 DC motors are used. The left/right
movement motor(trolley) is rated at 16V, 2amp. The other motor(hoist) is
rated at 28V, 2.2amp.

The motors are each controlled by a L6203 DMOS full bridge driver. One
uncommon thing about my circuit is that the L6203 input voltage, Vs are
powered by a standard benchtop DC power supply. Since the DC power supply
has 2 output(normally), one half will power the trolley motor while the
other will power the hoist motor.

For a start, I will set the power supply to supply only 3/4 of the max
voltage into the Vs pin. The current will be set to the maximum (i.e. 2amp
and 2.2 amp).

1) My question at this point is, will such a configuration work? Is there
anything I should watch out for?
Is it ok that I does not have a snubber network in my circuit? A friend told
me that it would be unnecessary as the value of the capacitor(calculated) is
too small to be effective.


A PWM signal(20KHZ) goes into the enable pin of the L6203 to control the
voltage that will be sent to the motor. A 0V signal will stop the motor, 50%
PWM will cause the motor to run at half speed etc. Direction is controlled
by 1 pin of the microcontroller to the IN1 and IN2 input pins. The signal is
inverted before going into IN1 so that the voltage can toggle between
positive and negative.
Since my microcontroller is powered separately from the L6203, I have tied
the ground pin of the microcontroller to the ground pin of the L6203 such
that the PWM signal can be correctly detected.

2) Is there any serious flaws in my design?


Thanks alot!
Mark






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