LM5122: Power Management Lab Kit PRO issues

James Van Volkenburgh

Part Number: LM5122

Howdy!

I'm having issues using the TI PMLK PRO to demonstrate how a working BOOST converter works. I am following the lab kit manual (Experiment 13) trying to find the Duty Cycle of the board but cannot seem to get the board to respond correctly.

Details:
- 10 V input from a DC power supply
- Nodes TP10 and TP13 to Osciliscope
- Output Voltage measures at 24 V under no load
- [H3-H8 sh, J13 op, J14 op, J15 op, J18 sh, J19 op, J20 op] || sh: shorted, op: open

PIN Attempts:
- With J15 sh
- With J15 op

- With J16 op
- With J16 sh left side

- With J9 sh
- With J9 op

Load Attempts:
- 5 kOhm
- 400 Ohm
- 300 Ohm
- 200 Ohm
- 100 Ohm
- 50 Ohm

Each attempt results in a garbage signal from the switching node seen by the oscilloscope and a voltage drop from 24 V to around 11 V (15 V for the 400 Ohm attempt). I have followed the lab manual precisely and accurately and cannot seem to get the board to work. How do I get this board to work successfully?

Thanks and Gig'em!
James Van Volkenburgh
Electrical Engineering Undergraduate

over 7 years ago

0 EricLee over 7 years ago

TI__Guru 59001 points

Hi
I think you are seeing DCM operation. Would you please post the TP10 waveform?
Regards,
EL

0 James Van Volkenburgh over 7 years ago in reply to EricLee

Prodigy 40 points

Howdy!

Thanks for the quick reply. I will get those waveforms for you mid-day tomorrow! I'll include the waveform without a load, then with a load.

0 James Van Volkenburgh over 7 years ago in reply to EricLee

Prodigy 40 points

Here is the waveform under no load.

Here is the Voltage Drop when pulling a load of 200 Ohms

Here is the waveform between TP10 and TP13 (GND) under said load.

Boost Converter PDF.pdf Here is a PDF in case the images don't work.

0 Garrett Roecker over 7 years ago in reply to James Van Volkenburgh

TI__Mastermind 21720 points

Hi James,

I am assuming that you mean experiment 1 of the PMLK-BOOST Experiment Book not experiment 13.

I am also not sure what what you are referencing when you mention H3-H8. Can you please explain?

- [H3-H8 sh, J13 op, J14 op, J15 op, J18 sh, J19 op, J20 op] || sh: shorted, op: open

The proper setup can be found on page 30 and 32 for experiment 1 in the book.

-Garrett

0 James Van Volkenburgh over 7 years ago in reply to Garrett Roecker

Prodigy 40 points

Howdy!

In my kit, I not only have the Boost, but also other boards, e.i. Buck Converter. I have the PMLK-PRO Experiment Book. However, I assume Chapter 1 in the boost experiment book correlates to the first experiment in my boost section (Experiment 13). H3- H8 is what connects one of the two inductors. J13, J14, J15, J18, J19, and J20 are all pins on the board that you either short or leave open. I have followed the instructions in the manual to the tee with no success. I also tried the Buck converter without any issues and believe I might have a faulty boost converter board.

0 Garrett Roecker over 7 years ago in reply to James Van Volkenburgh

TI__Mastermind 21720 points

Hi James,

Please make sure that you are using the 10uH inductor. Also J14 should be shorted as specified on page 30 of the PMLK-Boost Experiment book.

Also please make sure that your input power supply is not current limiting. Most of the time it is something simple causing the issue.

-Garrett

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LM5122: Power Management Lab Kit PRO issues