Pololu Dual VNH5019 User Manual

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Each VNH5019 motor driver IC has a maximum continuous current rating of 30 A. However, the chips by themselves
will overheat at lower currents. In our tests on a sample unit, we were able to deliver 30 A for a few milliseconds,
20 A for several seconds, 15 A for over a minute, and 12 A for around five minutes. At 6 A, the chip just barely gets
noticeably warm to the touch. The actual current you can deliver will depend on how well you can keep the motor
driver cool. The shield’s printed circuit board is designed to draw heat out of the motor driver chips, but performance
can be improved by adding a heat sink.

This product can get

hot

enough to burn you long before the chip overheats. Take care when handling this

product and other components connected to it.

Many motor controllers or speed controllers can have peak current ratings that are substantially higher than the
continuous current rating; this is not the case with these motor drivers, which have a 30 A continuous rating and over-
current protection that can activate at currents as low as 30 A (50 A typical). Therefore, the stall current of your motor
should not be more than 30 A. (Even if you expect to run at a much lower average current, the motor can still draw
short bursts of high currents, such as when it is starting, if special steps are not taken.)

If your motor has a stall current over the driver’s continuous current rating of 12 A per channel, we recommend
you take extra steps to make sure that your motor will not be exposed to loads that will cause it to exceed 12 A
for prolonged periods of time (or you take extra steps to keep the motor drivers cool, such as increasing air flow or
adding heat sinks). Exceeding 12 A for long durations should not damage the shield, but it will eventually activate the
driver’s thermal protection, which might result in inadequate performance for your application.

It is not unusual for the stall current of a motor to be an order of magnitude (10×) higher than its free-
run current. If you do not know your motor’s stall current, you can approximate it by measuring the
current it draws while held stalled at a lower voltage (such as when powered from a single battery cell)
and then scaling that value linearly with voltage. For example, the stall current of a motor at 6 V is
six times the stall current of that motor at 1 V. Another, less accurate method is to use a multimeter
to measure the resistance between the motor terminals and then use Ohm’s law to compute the stall
current I at voltage V: I = V/R. This last method generally is not as reliable because it can be difficult
to measure such small resistances accurately.

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, first double-check that your power supply is adequate, then consider
taking the following steps to decrease the impact of motor-induced electrical noise on the rest of your system:

Pololu Dual VNH5019 Motor Driver Shield User’s Guide

3. Getting Started with an Arduino

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