Decentralized Power Distribution Architecture

RE: Decentralized Power Distribution Architecture

jw0752 — Sat, 26 Jan 2019 04:43:33 GMT

One of the things I like to do is to order in a component like the MP2363 and then bread board it and play with it. Since the parts arrived today I mount the MP2363 on an adapter board and built the recommended circuit around it. The chip comes with a central solder pad that is tied to ground which my adapter board did not support but at the current levels (up to 500 mA) that I tested, it did not seem to matter.

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Initially I put a 1K resistor across the output for a load but soon added the Electronic load and settled on a 250 mA load. The unit is advertised to operate at 365 kHz and this one was solid at 347.2 kHz. I set the control resistors up to produce the 2.5 volts in the recommended circuit and then I experimented, replacing the 16.9K resistor to get higher voltages and lower voltages. For my final tests I settled on a 47K resistor which produced an output of 5.3 volts. Tests were made at various input voltages and loads up to 500 mA. The unit was stable as long as the input voltage was 2 volts above the output voltage. I could detect no significant heat in the MP2363 even at 500 mA. Here is a picture of a wider view of the lay out:

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I initially had some problems getting the circuit to work properly but as is usually the case it was me forgetting to provide the poor thing with a critical component or connection. In this case I forgot to tie the pin 4 to ground. Surprisingly the unit worked even without the ground but the frequency was 42 kHz and the output had no ability to support a load. Go figure!. Once the ground was attached no further problems were encountered

Here is the instrumentation:

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At the time of this picture the input voltage was 13.3 Volts and the input current was 120 mA. Output voltage was 5.3 Volts and the load on the output was 257 mA. My calculator says that that is 85% efficiency which isn't bad considering the long wires and bread board configuation.

The MP2363 is a great little Step Down Converter and of course it was a lot of fun to play with.

John

RE: Decentralized Power Distribution Architecture

jw0752 — Mon, 21 Jan 2019 03:55:04 GMT

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Red 12+ Black Ground White 1 V Orange 1.7 V Blue 3.3 V Brown 5.3 V

Tonight I decided to see if I could excise the 4 Step Down circuits from the larger board and still have an operational power section. I studied the layout and made my best guess as to where I could cut the board and not cut required circuitry. I used the SMD rework station to get a couple of larger ICs out of the way of the saw. When I first powered up the unit after cutting I had only the 5.5 volt section working. Trouble shooting and comparison of the sections showed that the enable pin 7 of the three down MP2363s was low. The data sheet indicates that pin 7 should be allowed to float for auto power up. The 5.5 volt section was already open but the other 3 sections were tied back to one of the chips I had removed to avoid the saw cut. Apparently the 1V, 1.7V, and 3.3V were designed to be powered on at the control of the chip I removed. With this insight I cut the trace to pin 7 on each of the non-functional MP2363s and tried once again to see if the unit was working. Once I had the unit working I also added a load to each channel. I did not try the three amps advertised in the data sheet as my jumper wires would have been stressed by this amount but I did subject each section individually to 2 Amps of load. To me it is simply amazing that these small DC converters can deliver 3 Amps with so little heat and such amazing voltage stability.

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Simple experiments like this one always seem to net a little additional knowledge. Now I know that I can turn the chips on and off with the number 7 enable pin. This information was in plain sight in the data sheets but it always helps my learning process if I have to get physically involved with the process.

Now I have to keep this circuit in mind so I can incorporate it into a future build somehow.

John

RE: Decentralized Power Distribution Architecture

DAB — Sun, 20 Jan 2019 20:18:44 GMT

Good job of reverse engineering John.

We will make an electronics engineer out of you yet.

DAB

RE: Decentralized Power Distribution Architecture

genebren — Sun, 20 Jan 2019 16:13:11 GMT

That board is a relative gold mine just in those power circuits. You could salvage parts for a few projects right from that corner of the board.

Have fun!

Gene