Building a motor control into my project

Other Hardware Motors, Mechanics, Power and CNC
1

My project needs a motor control that can handle 5 amps continuous. The monster moto shield from sparkfun looks like it uses a good h bridge that isn't beyond my scope of soldering. In this schematic, am I correct that I can just take the part I circled in yellow, and that's all I need to add this motor controller to my Arduino project? I'm not sure if I need Q1, D1, & R9. I can't tell what they do, but I'm guessing they work together? I just need a basic PWM motor control for 1 motor (12 volts, 5 amps), no current sensing or limiting, or anything else...

2

I expect you will need all the resistors and capacitors. You probably also need the two MOSFETs and the Zener diode which I think are to protect the system against short-circuits.

3

Hmmm. After searching some more, it seems to make 5 amp controller isn't so easy. I've always been used to the Arduino motor driver tutorial that uses the L293. It's a 5 minute setup.
http://itp.nyu.edu/physcomp/Labs/DCMotorControl
(This is a great tutorial!)
Is there not just a beefier L293 type of chip that would let me control 5 amps instead of 1?

4

A quick search at DigiKey.com shows a number of 5A H-Bridge chips from ON Semiconductor and Freescale Semiconductor. They are all surface-mount chips.

5

Ok. I'll search one out and post back if it will work. It seemed there were a lot of other components involved with many 5 amp or heavier controllers but they were MOSFET type controllers. I'll see what u find in te H bridge line.

6

I like the looks of the VNH5019 chip. I found the schematic at Pololu,and I think I understand it all.

A couple questions I have.

Will this MOSFET work for Q1?

What are C2A & C2B?

I found the main VHN5019 IC here, I think?

Thanks.

7

Will this MOSFET work for Q1?

The notes for Figure 4 in the VNH5019A-E datasheet (http://www.st.com/internet/com/TECHNICAL_RESOURCES/TECHNICAL_LITERATURE/DATASHEET/CD00234623.pdf) list the requirements for the MOSFET used for reverse-battery protection. Figure 5 shows the circuit without the MOSFET.

What are C2A & C2B?

I don't see those in the Pololu schematic.

8

johnwasser:

Will this MOSFET work for Q1?

The notes for Figure 4 in the VNH5019A-E datasheet (http://www.st.com/internet/com/TECHNICAL_RESOURCES/TECHNICAL_LITERATURE/DATASHEET/CD00234623.pdf) list the requirements for the MOSFET used for reverse-battery protection. Figure 5 shows the circuit without the MOSFET.

What are C2A & C2B?

I don't see those in the Pololu schematic.

C2A & C2B are at the top right...

The datasheet says,
The external N-channel Power MOSFET used for the reverse battery protection should have the following characteristics:

  • BVdss > 20 V (for a reverse battery of -16 V);
    .......this is true
  • RDS(on) < 1/3 of H-bridge total RDS(on)
    ..........the RD(on) for the MOSFET is 3.9, is that ok?
  • Standard Logic Gate Driving
    ...........the datasheet for the MOSFET says, N-channel logic level, so that's ok?

Thanks for the help, and thanks for the help learning how to read datasheets, too.

9

What are C2A & C2B?

I'm not sure what they are for but the value "NP" means "Not Populated" so you don't need them.