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Topic: Driving low-power dc motor (Read 744 times) previous topic - next topic

PacificSan

Hello,

I will be using a low-torque (6 oz-in) dc gearmotor with a range of 1.5 - 3V. Is there a way to power this motor with an H-bridge (L298n) without potentially damaging the motor? The H-bridge needs a minimum of 4.5 V.

Magician

It's o'k to power bridge with 5V, if you're using PWM control "effective" voltage would be lower. For example, analogWrite(9 , 128) will set less than 2.5V outputs. You can power motor from arduino if it drain less than 500 mA, otherwise you need external PS

PacificSan


It's o'k to power bridge with 5V, if you're using PWM control "effective" voltage would be lower. For example, analogWrite(9 , 128) will set less than 2.5V outputs. You can power motor from arduino if it drain less than 500 mA, otherwise you need external PS


Just to verify and be sure, it is okay to power the motor through a 5 V bridge, as long as the PWM results in a voltage less than the maximum operating voltage for the motor. Am I correct?

Magician

Yes, about right. Even if you overdrive PWM to 100%, source / sink saturation voltage of the IC would eat up 1.5-2.5V or so, and unlikely that motor will get more than 3.5V.

MarkT

The torque specification with no other information doesn't help us - the running current and stall current are the
important parameters to consider when driving a motor - just provide a link to the motor you are considering, then
our answers won't be all guesswork.
[ I won't respond to messages, use the forum please ]

PacificSan

Here's a link to the datasheet for the motor. It is included as part of a larger gearbox assembly kit.
The no-load current ranges from 95 -160 mA, while the stall current ranges from 1.4 to 2.7 A.

http://www.pololu.com/file/0J17/re_260ra.pdf

Would using an H-bridge still be safe at these currents?

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