Newbie with motor drivers

Hi, I got a presales question

I want to control a automotive blower motor’s speed , the motor is 12vdc, rated at 12a, and is brushed
so… I look at 18v25 CS or VNH5019…
also, I only need to go one direction…
and I already have my microcontroller board…

I see there are many ways to control, it…
what do I want?
Sign-magnitude (drive-brake)
Sign-magnitude (drive-coast)
Variable braking (brake-coast)

going to matter for a simple blower fan?

the VNH5019, seems so simple …

any advice?


I am unclear on what your 12A current rating means (e.g. stall current, current draw at peak efficiency, etc.), so I cannot make a confident recommendation. I suspect that the 18v25 would work for you. You might also consider using our dual VNH5019 motor driver where a single motor is connected to both channels. You can find more information on how to connect both channels to a single motor inside the “Using the Driver in Single-Channel Mode” section of the user’s guide.

I recommend sign magnitude (drive-braking) as a simple way to control that motor.

  • Grant

well… I cant exactly tell you what 12a current means, cause they just tell me that on the specs
im waiting to get one in my hand…

am I over kill? since I only need 1 direction, do I need 1/2 bridge?
or just a single mosfet driving the motor

I have to add, you guys here at pololu are really great at your product descriptions, the details are fantastic
also you products are TOP!!!

im going to try it with the VNH5019, now since I loose current sense, will fault from the chip, tell me about a stall?
should I add an Allegro current sensor to my final design to be sure nothing say jams motor and causes current to flow out of control
and possible meltdown


Since you just need unidirectional control, a suitably powerful MOSFET would suffice. As for preventing damage from over-current, I would not rely on the VNH5019’s integrated protection to protect the rest of your system, especially if you are using multiple H-bridges in parallel as I have suggested. You could use an external current sensor like you mentioned, or you might consider adding a fuse.

  • Grant