Pololu Simple Bedienungsanleitung PDF herunterladen (Seite 28)

Power Considerations

The Pololu Simple Motor Controllers can be powered either from USB using a USB A to mini-B cable

[http://www.pololu.com/product/130] or from a power supply, such as a battery pack, connected to the large VIN and GND

pads. When the VIN supply is not present, the controller can use USB power to perform all of its functions except for

driving the motor. The controller automatically selects VIN as the power source when it is present, even when USB

is connected. It is OK to have both USB and VIN power simultaneously connected.

Power for the motor must be supplied to the controller through the large VIN and GND pads. The smaller

VIN and GND pads on the left side of the board in the diagrams above are not suitable for high currents

and should not be used to power the motor controller. These smaller power pins provide a convenient way

to pass the input voltage on to other parts in your system, but they should not be used to power anything

that will draw more than 500 mA.

All Simple Motor Controller versions can operate from VIN supplies as low as 5.5 V, but the maximum continuous

output current will be lower for voltages under 7 V. The maximum power ratings for the Simple Motor Controllers

are shown below:

Simple Motor Controller 18v7 18v15 24v12 18v25 24v23

Absolute max voltage 30 V 30 V 40 V 30 V 40 V

Recommended max voltage 24 V 24 V 34 V 24 V 34 V

Max continuous current w/o heat sink 7 A 15 A 12 A 25 A 23 A

It is very important that you select a power source that does not exceed the absolute maximum voltage rating for

your Simple Motor Controller. Ripple voltage on the supply line can raise the maximum voltage to more than the

average or intended voltage, so we recommend you to select a voltage that leaves at least a 6 V margin for noise. It

is also important to note that batteries can be much higher than their nominal voltage when fully charged, so we do

not recommend using the 18v7, 18v15, or 18v25 versions with 24 V batteries unless appropriate measures are taken

to limit the peak voltage.

For 24 V applications, we recommend the 24v12 or 24v23 versions. We strongly recommend against using

the 18v7, 18v15, or 18v25 with 24 V batteries, which can significantly exceed 24 V when fully charged

and are dangerously close to the maximum voltage limits of these lower-voltage controllers. Using a 24 V

battery with an 18vX Simple Motor Controller makes the device much more susceptible to damage from

power supply noise or LC voltage spikes.

Finally, make sure you select a power source that is capable of delivering the current your motor will require (e.g.

alkaline cells are typically poor choices for high-current applications), and place a large capacitor across power and

ground near the motor controller to limit electrical noise (such a capacitor is pre-installed on fully-assembled 18v7,

18v15, and 24v12 controller versions).

The Simple Motor Controllers feature a configurable low-voltage shutoff that can help you avoid

damaging batteries that are sensitive to over-discharging, such as Li-Po packs. See Section 5 for more

information.

4. Connecting Your Motor Controller Page 28 of 101

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Pololu Simple Bedienungsanleitung Seite 28