Lab 6

The questions below are due on Tuesday March 17, 2026; 06:00:00 PM.
 
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Learning Objectives

Today's lab will focus on assembling and testing your buck converter boards.

  • Solder the surface mount parts.
  • Solder through-hole parts.
  • Test your boards!
  • Get a checkoff.

Buck converter assembly

This is now the second board that you designed and made. We'll approach the assembly much like we did for the sensor boards, just with different components.

However, since we're kinda pro at this now, we'll simplify the instructors. Feel free to refer to lab05 when you want more detail.

Surface Mount

We're going to start by soldering in the SMT parts.

  1. Apply solder paste to all the pads for the SMD parts: Resistors, Capacitors, Inductor, LEDs, and the TPS62A01 IC pads.

  2. Get all your parts. Some R's and C's are from the EDS main room, the resistive divider ones and the rest of the parts are from the 6.900 area. The IC is in the parts cabinet

We have a set of resistor values in our parts cabinet that you may want to use for your resistive divider: 93.1k, 95.3k, 97.6k, 442k, 453k, 464k.

The inductor you want is the 1 uH 3.3A inductor with part number 490-13053-1-ND from the parts cabinet.

  1. Place the components on the pads, and then use the hot plate to reflow the solder. Should be the same as last week, but a bit easier cause the IC pads are bigger.

Some checks

Bad soldering for the IMU boards usually results in the IMU just not working till you fix it. Bad soldering for power converters often results in blue smoke and the need to get a new IC. So we're going to do more extensive checking before firing it up.

Checkoff 1:
Ask a staff member to look over your assembled board.

Thru-hole

After your board has been checked by staff, get a 1x3 right-angle header (same as we used in lab01) and solder that in.

Testing the Board!

Now let's verify that your buckboard works in your system.

When you insert your board, if any of the components start to get super hot or smoke, that's bad and a sign that something is probably shorted and you should unplug it immediately.

  1. With your existing LDO board in place, compile and upload the starter code from lab05, the one that prints out accelerometer readings. Start up the serial monitor so you can verify that your system works.

  2. Take out your LDO board. Plug in your new buck converter board. Your sytsem should start back up, the status LEDs should light back up and the serial monitor should start printing again.

If the LEDs don't light up and the serial monitor doesn't start printing, unplug the buck board and ask for help.

  1. Next, take a look at the 3V3 coming out of the buckboard (hmm... where would one look to test a signal?) on an oscilloscope or a Joulescope. Your output may have some blips when load changes, but it should be pretty stable and not noisy!

Checkoff 2:
When you get things working, find a staff member and allow them to join you in celebration of your second working PCB!