3A (6A Peak) LMD18200T Motor Driver Board

Description:This is a motor driver board for brushed DC motors. The motor driver is capable of driving up to 55V motors @ 3A continuously (6A peak). The REQUIRED digital inputs are DIRECTION and PWM. There is an optional BRAKE input that may be used if the jumper is removed.

Please read the datasheet available at:

Schematic:The schematic of the board shown below.

Please note that during testing and setup, the input pins should not be left floating (i.e., not connected to anything) because the motor may act erratically.

Additionally, the frequency of the PWM signal driving the motors should be between 1-5kHz. However, this is not an exact value and it may be varied as needed. However, if the period interval is too slow, the motor driver chip may overheat and go into thermal shutdown. It is a good idea to verify proper operation over an extended amount of time BEFORE finalizing any software for your robot (and WELL BEFORE demo day).

The following items are needed for EACH driver board:

  1. Heat Sink (Newark Electronics PN: 52F-6207), 1 required.
  2. Driver Chip (National Semiconductor PN: LMD18200T), 1 required.
  3. Motor driver circuit board (available from Dr. Arroyo), 1 required.
  4. Bypass capacitors (0.01uF, should have some in IMDL lab), 2 required.
  5. Two pin male header (available in IMDL lab), 1 required.
  6. Four pin male header (available in IMDL lab), 1 required.
  7. Two position terminal block (Radio Shack PN: 276-1388), ½ of a Package required (2 two-position blocks required, 4 are in a package).
  8. Heat sink compound (Radio Shack PN: 276-1372), less than 1 tube.

Note: To obtain the driver IC’s from National Semiconductor for FREE, follow these steps:

  1. Go to
  2. Scroll down to Package Availability, Models, Samples & Pricing.
  3. There is a Samples link. Click on it.
  4. Follow the instructions.
  5. You may order up to 5 samples (if you need less, order 5 and I can use the extra drivers).
  6. Have the shipment sent to your home address.

Assembly Instructions

The blank PCB with all of the required parts is shown below. Note the PCB is shown with the top up.

Place the motor driver chip as shown. I prefer to use a rubber band to hold the IC and other components in place while soldering. Note that the image below is of the BOTTOM of the circuit board. You can tell the top from the bottom by the letters SDN ’01 on the top of the board.

After placing the IC chip in the holes and securing it with a rubber band, solder the IC to the board.

Repeat this process for all of the components. Do NOT solder the heat sink yet.

Insure that all of the components are soldered into place as shown below.

Place a small blob of heat sink compound on the back of the IC.

Spread the compound evenly over the back surface of the IC (you may want to use the heat sink as a squeegee to do this).

After the compound is spread evenly, slide the heat sink onto the IC and make sure that the mounting leads of the heat sink are seated properly into their mounting holes. Solder the heat sink into place.

The board is now finished and ready to use. Please note that the motor driver IC is static sensitive, and therefore you should be careful when carrying the board. Also note that a jumper is required if you are not using the brake signal. Here is what the finished board should look like:

Have fun and don’t blow anything up…

©Scott Nortman 2001