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I'm analyzing the included PCB in a Harbor Breeze solar light (model SL1832) to see if I can repurpose any parts of it for use in a LoRa mesh network node. There's this small IC marked AAYav, but when I search that code in an SMD marking database, none of the options that come up seem to match.

Some testing reveals the IC seems to cut voltage to the output (the two wires on top) when the battery voltage drops to 2.8 V, so I'm guessing it's some kind of voltage supervisor, but if anyone happens to know the exact component, I'd love to know more. On a related note, would love to know what the capacitor C1 is for.

Here are some pictures of the PCB: Top down view of PCB used for battery charging in Harbor Breeze solar light Backlit view of the same PCB revealing more details on how the traces are laid out, flipped vertically for readability

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  • \$\begingroup\$ The chip marking is consistent with the Ricoh voltage regulator -- see pgs 19-20 on the datasheet: mouser.com/datasheet/2/792/rp107-ea-923721.pdf. However the circuit does not seem to line up at all... \$\endgroup\$ Commented Oct 7 at 23:54
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    \$\begingroup\$ You need to determine what function this microcircuit performs. To do this, you need to draw a diagram by hand. There are several microcircuits with this marking, each with a different purpose. \$\endgroup\$ Commented Oct 8 at 5:36
  • \$\begingroup\$ (Those are very cold solder joints). Maxim likes to mark everything in cryptic ways like this with lots of AA... Unfortunately they no longer document how their parts are marked thanks to the merger with AD. \$\endgroup\$ Commented Oct 8 at 6:29

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I might have figured it out!

I think this IC is an XC6114 series voltage detector, specifically the XC6114B629MR. Here is the datasheet.

From the datasheet, the pinout is (starting from the bottom left pin and going counter-clockwise):

  • 1 - RESETB
  • 2 - Vss (Ground)
  • 3 - RESET
  • 4 - WD (Watchdog)
  • 5 - Vin

Here's how it seems to be used here:

  • Over-discharge protection for the included 3.7v 1500 mAh 18650 Li-Ion battery, cutting power around the 2.9v threshold.
  • Automatic power shutoff to the output (the LED light) when the solar panel is active

I'm still not entirely sure how this particular chip accomplishes this, but I'm assuming it's got something to do with the watchdog functionality. The WD pin seems to take the solar panel as input to switch RESET and RESETB so that the LED remains off during the day.

Here's the circuit diagram I was able to puzzle out: Circuit diagram of the PCB used in this Harbor Breeze brand solar light. The negative leads of the battery and solar panel are connected together. The positive lead of the solar panel goes to the WD pin of the IC. The RESETB and Vss pins of the IC are connected together and lead back to the shared negative leads of the battery and solar panel. The RESET pin of the IC goes to the positive LED through-hole. There is a polarized capacitor with 1 microfarad capacitance allowing current to flow from the RESETB path to the LED path. In the middle of the PCB, there is a single pole double throw switch that either shorts the LED path to the positive battery terminal, or shorts two leads on the same ground plane, doing nothing and keeping the light off as a result. Finally, two 15 Ohm resistors sit in between the LED negative leads and the Vin pin of the IC.

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  • \$\begingroup\$ I'm not sure why , but I'm getting "Content not viewable in your region" on a blue background instead of an image of the circuit diagram. \$\endgroup\$ Commented Oct 8 at 22:06
  • \$\begingroup\$ Yeah, Imgur's policy is... weird these days. Just paste it in the compose window and it's hosted by Stack. \$\endgroup\$ Commented Oct 8 at 22:54
  • \$\begingroup\$ I attempted that, but the image wouldn't paste for me for some reason. I got stuck having to host it on Imgur for that exact reason. Seems the inline answer compose window doesn't support Slack image pasting, but the dedicated window that appears when you edit an answer does support it. Fixed it now, regardless. \$\endgroup\$ Commented Oct 9 at 14:34
  • \$\begingroup\$ I might say something stupid, but this marking is very similar to the TL431ASA-7 chip (SOT23-5). \$\endgroup\$ Commented Oct 9 at 18:20
  • \$\begingroup\$ This can't be the XC6114B629MR chip. It's marked with 4 characters, but you have a chip with 5 characters. \$\endgroup\$ Commented Oct 13 at 8:10

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