Control brushed motors with 3.7v cell lipo


I have to control a very tiny small brushed motor that works with a 3.7v single cell lipo battery. The only thing that I have on hand to connect arduino to control this motor is a buk9507. I already used this FET to control things with 8v and even more, but I am not sure if it will work.

My other issue is that even if you say I can use 3.7v with this buk9507 chip, can I connect drain pin of this chip to 5v arduino pwm pin and control the 3.7v on the drain-source? I know this is a logic fet and it is supposed to work with 5v at the gate, but I never see someone use a higher voltage on the gate than in the drain-source.

[u]MOSFET driver circuit[/u].

can I connect drain pin of this chip to 5v arduino pwm pin and…

Yes, the drain can go to the motor which is powered by a lower voltage. But, the gate goes to the 5V PWM. :wink:

@DVDoug thanks! I was afraid of that and thanks for clearing this out! But do you think this chip can work with 3.7v? Cause the datasheet says 12v, it does have say a minimum voltage and becuse of that I thought the mininmum would be the logic voltage (5v).

If you look at the datasheet ( do so) you'll find that a Vgs of 3.7v is borderline on the way to low Rds.

But even if your 3.7v LiPo is powering the arduino as well as the motor ( you say very tiny) it ought to be OK.

Note that 3.7v is the voltage at which a LiPo is almost completely discharged. Fully charged would be 4.2v, which is plenty..


Yes, its a bit borderline - remember there is a big spread on plateau voltages for MOSFETs, a volt or more
of variation between devices, and its only rated for 5.0V or above gate drive. You'd be better off with
one rated at 4.5V (which most logic level MOSFETs are), or preferable 3V of course.

My intuition is that it will likely work well with a few amps load, a small chance your particular device is
going to run hot.