I'm working on a project to control a small brushed DC motor (3V, 0.15A), and trying to make the board as cheap as possible (by necessity 
). Can you help me find the part(s) to drive the motor?
The problem is deciding in the parts to switch power to the motor. I'm using an MSP430 to generate the control signals, and would like to use back EMF measurement as a rough speed gauge to do closed loop control of rotational speed. The power source is a pair of AA batteries, so I've looked at existing H-bridge chips designed to operate at 1.8V as well as discrete transistors for making a custom H-bridge. The motor can get away with turning in only one direction, so a half bridge would also be OK.
I found the DRV8837 from TI, but it is a bit too expensive even considering it includes built-in protection circuitry.
Are there other less expensive integrated H-bridge or half bridge chips out there that could drive this motor? If not, are there particular discrete transistors that would work well? Since the system is already low voltage, I think I'd prefer to use *MOS parts to avoid the voltage drop of traditional TTL transistors. Something that includes or enables easier back EMF measurement would be great (advice on back-EMF measurement/schematics also welcome).
Thanks!
). Can you help me find the part(s) to drive the motor?The problem is deciding in the parts to switch power to the motor. I'm using an MSP430 to generate the control signals, and would like to use back EMF measurement as a rough speed gauge to do closed loop control of rotational speed. The power source is a pair of AA batteries, so I've looked at existing H-bridge chips designed to operate at 1.8V as well as discrete transistors for making a custom H-bridge. The motor can get away with turning in only one direction, so a half bridge would also be OK.
I found the DRV8837 from TI, but it is a bit too expensive even considering it includes built-in protection circuitry.
Are there other less expensive integrated H-bridge or half bridge chips out there that could drive this motor? If not, are there particular discrete transistors that would work well? Since the system is already low voltage, I think I'd prefer to use *MOS parts to avoid the voltage drop of traditional TTL transistors. Something that includes or enables easier back EMF measurement would be great (advice on back-EMF measurement/schematics also welcome
).Thanks!
