MCP73871 and TPS61090 Troubleshooting

[Colby_Allen]

I apologize in advance if I violate any forum conventions here. If that happens I will adapt postings accordingly moving forward. I’m not expecting to be spoonfed here, more so just wondering if anyone has encountered a similar challenge in their journey.

Here is the archived KiCad project (From Kicad version 7.0.9, but I can convert this if anyone on another version is has time or is interested in taking a look)

Context:
I have been working on a PCB design that incorporates the TPS61090 (Boost converter) and MCP73871 (Charge controller) of Adafruit’s Powerboost1000C.

I’ve checked the Powerboost1000C circuit diagrams and Eagle PCB board files provided by Adafruit, and pretty meticulously matched everything to spec. However, when I plug this in, the boost converter chip (TPS61090) gets extremely hot, and yes, eventually starts smoking.

Circuit:
For power, I will be switching between a +5V USB and a 3.7V-4.2V Lipo battery supply. The power circuit is the portion highlighted in Yellow, where the microUSB port feeds USB power from the Teensy’s VUSB pin (#1) to a MCP73871 charge controller (U2, #2). Directly below this are two terminals (Orange) where the battery joins the circuit. Both power sources then feed into the TPS61090RSAR boost converter (U1, #3). If the battery is discharging, the 3.7V-4.2V will be stepped up to +5V here. Finally, power is delivered back into the Teensy through the +5V “VIN” pin (#4). The following image depicts this flow:

Power Flow (Yellow):

TPS61090 (Boost Converter):

MCP73871 (Charge Controller):

Physical Board:

Additional Project Files:
Here are the Gerber/Drill files that I used to have this board fabricated

And here is the full schematic of the board. For some reason, the resolution when zooming is much better on the mobile app (You can even read the text on the datasheet pinouts).

2 Questions:
Having read elsewhere that the passives (Capacitors, resistors, etc.) might need to be placed closer to their respective ICs, I have two questions:

1. Could I be missing decoupling capacitors; 10 or 100nF caps, placed close to all power inputs?

2. I’m thinking a board revision is the best plan of action moving forward. Are there any steps that I might want to take before that?

[ekoeck]

If something gets hot and starts smoking it won’t be because of missing decoupling capacitors (except in very rare cases). Best start with disconnecting (by cutting the traces) the TPS from the MCP and check if the MCP works correctly. If so connect the TPS again and disconnect the load and so on. So you will eventually find out where things go awry. No use in doing a revision, if you don’t know what’s causing the trouble.
Pro-tip: when designing multi stage power supplys add 0R resistors/solder jumpers in front of each stage to a) verify the function step-by-step without frying something and b) be able to solder on a wire and supply the power with a lab supply if some stages don’t work properly.

HTH

[paulvdh]

You have an extremely verbose way of saying … very little.
In your long post, I can not figure out what the actual problem is you want to solve.

Looking at the pictures you posted, the track layout looks extremely bad for an SMPS circuit. SMPS circuits have both fast changing currents and voltages, and this makes track layout extremely important.

So I thought, maybe I missed something, and decided to do a download of your project.
1283 files and nearly half a GiB of data:

4 kicad projects in one directory:

paul@cezanne:~/downloads/WDM(RevB_V2)$ ls -hl *pro
-rw-rw-r-- 1 paul paul 6,8K Apr 30 02:44 ‘Adafruit PowerBoost 1000C Rev B.kicad_pro’
-rw-rw-r-- 1 paul paul 18K May 26 01:32 teensy_beats.kicad_pro
-rw-rw-r-- 1 paul paul 12K May 13 16:21 ‘WDM(RevB_V1)_backup_5.13.24.kicad_pro’
-rw-rw-r-- 1 paul paul 17K Aug 18 17:52 ‘WDM(RevB_V1).kicad_pro’

I also see gerber files both in the project root, and in sub directories. Directories with other projects inside your “root” directory.
That is were I gave up. I am not wading though that mess and deleted the whole thing.

I was already fearing for something like that when I read your post with all sorts of (random?) details but little structure and saw your posted schematic with al those datasheet pages pasted into it.

I guess you have some serious organizational problems, but you probably already knew that. It’s also something I can not help with.