3.1. Choosing the power supply and motor

The information in this section can help you select a power supply and motor that will work with the Motoron.

The Motoron is designed to work with brushed DC motors. These motors have two terminals such that when a DC voltage is applied to the terminals, the motor spins.

When selecting the components of your system, you will need to consider the voltage and current ratings of each component:

• The voltage range of your power supply is the range of voltages you expect your power supply to produce while operating. There is usually some variation in the output voltage so you should treat it as a range instead of just a single number. In particular, keep in mind that a fully-charged battery might have a voltage that is significantly higher than its nominal voltage.
• The current limit of a power supply is how much current the power supply can provide. Note that the power supply will not force this amount of current through your system; the properties of the system and the voltage of the power supply determine how much current will flow, but there is a limit to how much current the power supply can provide.
• The operating voltage range of a Motoron is the absolute range of voltages that can be supplied to the Motoron’s VIN and GND pins, which power the motors. The Motoron requires a DC power supply. The operating voltage range of each Motoron is listed on the Motoron category page and on each Motoron’s product page, both in the summary at the top and in the “Specifications” tab.
• The continuous output current per channel of a Motoron is the maximum amount of current that the Motoron can continuously provide to each motor. The output current for each Motoron is listed on the Motoron category page and on each Motoron’s product page, both in the summary at the top and in the “Specifications” tab.
• The rated voltage of a DC motor is the voltage at which the DC motor was designed to run. You can apply voltages to the motor that are higher or lower than its rated voltage, but higher voltages bring a risk of overheating the motor or reducing its lifetime.
• The no-load current of a DC motor is the current that the motor will draw if you apply the rated voltage to the motor while its output is not connected to anything.
• The stall current of a DC motor is the current that the motor will draw if you apply the rated voltage to the motor while forcing its output shaft to remain stationary.

There are guidelines you should be aware of when selecting the components of your system:

1. The voltage of your power supply should generally be greater than or equal to the rated voltage of each DC motor. Otherwise, you will not get the full performance that the motor was designed for. If your power supply’s voltage is much higher than the rated voltage of a DC motor, you might account for that by using lower speeds for that motor in your commands to the Motoron.
2. The voltage of your power supply should be within the operating voltage range of the Motoron. Otherwise, the Motoron could malfunction or (in the case of high voltages) be damaged. Additionally, we recommend that the voltage of your power supply should be at least 6 V less than the absolute maximum, which leaves a safety margin for ripple voltage on the supply line. Note that a fully-charged battery will have a voltage much higher than the nominal voltage.
3. The typical current draw you expect for each motor should be less than the Motoron’s continuous current per motor. Each motor’s typical current draw will depend on your power supply voltage, the speeds you command the motor to move, and the current ratings of the motor. For the Motoron M1T550, M1U550, M2T550, M2U550, M3S550, M3H550, M1T256, M1U256, M2T256, M2U256, M3S256, and M3H256, a motor that draws too much current could trigger the Motoron’s overcurrent or overtemperature faults, which shut down the motor. For the Motoron M2S and M2H, a motor that draws too much current could cause the board to overheat, resulting in permanent damage.
4. The current limit of the power supply should be higher than the typical total current draw for all the motors in your system. Furthermore, it is generally good for the current limit to be much higher than that so your system can smoothly handle the times where the motors are drawing more than the typical current, for example when they are accelerating or encountering extra resistance.
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