Motor considerations – Pololu Simple User Manual
Page 29
Motor Considerations
The two terminals of your brushed, DC motor connect to the OUTA and OUTB pins. When selecting a motor for
your controller (or a controller version for your motor), it is important to consider how the motor will be used in your
system. If the motor is likely to be stalled for prolonged periods of time or under heavy load, or if the motor will be
rapidly changing direction without acceleration limiting enabled, you should be taking into account the stall current of
the motor at the voltage it will be running and selecting a controller that can deliver a continuous current that exceeds
the stall current.
It is not unusual for the stall current of a motor to be an order of magnitude (10×) higher than its free-
run current. When a motor is supplied with full power from rest, it briefly draws the full stall current,
and it draws nearly twice the stall current if abruptly switched from full speed in one direction to full
speed in the other direction.
Occasionally, electrical noise from a motor can interfere with the rest of the system. This can depend on a number of
factors, including the power supply, system wiring, and the quality of the motor. If you notice parts of your system
behaving strangely when the motor is active (e.g. corrupted serial data, bad RC pulses, noisy analog voltage readings,
or the motor controller randomly resetting), consider taking the following steps to decrease the impact of motor-
induced electrical noise on the rest of your system:
1. Solder a
across the terminals of your motor, or
solder one capacitor from each terminal to the motor case. For the greatest noise suppression, you can use three
capacitors (one across the terminals and one from each terminal to the case).
2. Make your motor leads as thick and as short as possible, and twist them around each other. It is also
beneficial to do this with your power supply leads.
3. Route your motor and power leads away from your logic connections if possible.
4. Place decoupling capacitors (also known as “bypass capacitors”) across power and ground near any
electronics you want to isolate from noise.
Pololu Simple Motor Controller User's Guide
© 2001–2014 Pololu Corporation
4. Connecting Your Motor Controller
Page 29 of 101