2991 DC Motor Driver Question

I have a 24V DC Brushed motor that I am looking to drive with this board: https://www.pololu.com/product/2991


-I noticed there is a PWM input pin that needs to be connected to run the motor. The details of this product’s page state that this PWM input can be set to High (5V) or Low (0V) in order to run the motor. Is this correct? Or does the PWM pin need to have a PWM input?

I am curious because I would like to not have a PWM signal to run the board. I just want to put simple 5V logic to this pin to have the motor move

-The driver page states it is capable of running a motor continuously at 17A. The motor I have is rated for less than that, around 8A. Will the driver feed 17A continuously to the motor? Or do I need to incorporate the current limiting function? I would like to avoid using that if possible.



A PWM signal quickly switches between logic high and logic low, which effectively acts as a way to control the speed of the motor. For example, a PWM signal with 100% duty cycle is the same as supplying digital high (the motor is running at full speed), and a PWM signal of 0% is the same as supplying a digital low signal (the motor is not running at all). If the device that generates the PWM signal is a 5V device, then the PWM signal will quickly switch between 5V (high) and 0V (low). The inputs on our G2 motor drivers, which includes PWM, are compatible with 1.8V, 3.3V, and 5V logic. So, yes, you can just send a 5V (high) or 0V (low) signal to those inputs. You can also send PWM signals to the PWM pin, since those quickly switch between logic high and low.

In systems like this, current is not forced into the device. Instead, it is drawn by the device based on the load. So, a motor driver that can handle 17A will not force 17A into a motor. Instead, the motor will draw current based on its load, and a motor driver that can provide 17A continuously should be able to provide up to 17A to the motor. I recommend trying to find out under what condition your motor’s current rating was specified. For example, at what voltage was the 8A rating drawn? How much load was on the motor’s output (is this a stall current or the no-load current draw)? You can take a look at the “Specs” tab of any of our motor pages to get an idea of how we describe our motor’s specifications, and you can learn more about the various motor parameters under the first FAQ on the “FAQs” tab of any gearmotor product page.

By the way, if you do not need to control the direction of rotation of your motor, it sounds like you might be able to use one of our basic relay modules, like this one. If you tell me more about how you want to control your system or application, and generally describe the behavior you want from your motor, I might be able to recommend an appropriate motor controller.