Driving 3v motors with SN754410. 5v supply - please advise.

Other Hardware Motors, Mechanics, Power and CNC
1

Hello All

I have a bunch of 3v motors (Voltage Range: 1.5V to 4.5V nominal voltage 3V) and wish to drive them using a SN754410 Quad half-h driver.

The sheet for the driver states the chip is designed to drive voltages from 4.5-36V.

Since I do not wish to damage my motors and my supply voltage is 5V, would it be adequate to place resistors in series with the motors, on one of the 2 wires running to each motor from the SN754410 chip?

Thanks

2

Better than using series resistors (which waste power) is to use the principle of pulse-width modulation (PWM) to deliver an effective voltage of 3V from a higher input voltage. The analogWrite() function can be used for this purpose.

If, for example, you have a 9V power source you could use analogWrite(85) to generate a 33% duty cycle waveform and deliver an effective voltage of 9/3=3V.

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The Gadget Shield: accelerometer, RGB LED, IR transmit/receive, speaker, microphone, light sensor, potentiometer, pushbuttons

3

Hi There RuggedCircuits

I was under the impression that one could use PWM to controll the speed of the motor...

So I guess I could use PWM and never use percentage higher than 60% (if source is 5V) for my 3V motors, with PWM of 60% (PWM=153) as my full speed?

Cheers

4

That sounds correct.

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The Rugged Motor Driver: two H-bridges, more power than an L298, fully protected