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I'm trying to identify a component on a GoPro Hero10's PCB.

enter image description here

It measures 1x1mm and appears to be a UDFN-4 package (or similar). It is grouped with one capacitor and doesn't have an obvious connection to a larger IC.

I have highlighted all relevant traces I could identify. The board is an HDI PCB with about 10 layers and blind/buried, plugged micro-vias, which makes things difficult.

The connector on the right is for the GoPro's front screen, the one right next to the long red trace is for the USB port.

The test point above the component in question appears to be connected to a via which would end here if it went straight through all layers (it most likely doesn't):

enter image description here

Here's an overview showing the PCB in its entirety from both sides:

enter image description here

Here's a close-up of the chip in question:

enter image description here

I'm not sure what kind of component this could be, which makes searching for it really difficult.

Does anyone have an idea what it is?

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    \$\begingroup\$ I'm saving this question to refer to in the future for other "identify this component" type questions. Everything about this is an ideal example of how one should ask this sort of question. \$\endgroup\$
    – JYelton
    Jul 11, 2022 at 23:57
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    \$\begingroup\$ I fully agree! This has sharp pictures, good descriptions, highlights what you're asking about, gives an overview, names and explains measured voltages, states the device and application, explains your own thought process... Excellent! This is a question that someone reading in the future will benefit from! \$\endgroup\$ Jul 12, 2022 at 0:38
  • \$\begingroup\$ Could it be a logic IC, perhaps? I'm pretty sure you can get single-gate logic chips in a package like that (with the exposed pad acting as the fifth pin needed for two-input gates), and sometimes you do just need a single inverter or an or gate or something. \$\endgroup\$
    – Hearth
    Jul 12, 2022 at 0:47

2 Answers 2

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My bet would be an LDO:

Package and Marking seem to match.

enter image description here

http://www.analog.com.tw/ImgShow/DS-1701BG-01.pdf

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  • \$\begingroup\$ LDO was actually my first guess as well because the package seems to very common for LDOs but it would be missing an input (or output) capacitor and the potential input/output pins have the same voltage. The pinout doesn't match this particular LDO either: EN and GND would have to be swapped. There are also two large PMICs on the front of the PCB (ACT88760 and ACT9150, according to Hypoxic), which include multiple LDOs, so another stand-alone LDO would most likely be unnecessary. \$\endgroup\$
    – marvp
    Jul 12, 2022 at 0:38
  • \$\begingroup\$ @marvp Input capacitors aren't strictly required for most linear regulators, so it would be possible to not have one. The other reasons you give are good reasons to doubt that this is one, though. \$\endgroup\$
    – Hearth
    Jul 12, 2022 at 0:47
  • \$\begingroup\$ My lousy reasoning (spent 10 seconds on it) was that it could be a specific LDO for the SD card or something like that. Being 3.3V output would explain why In/Out are the same (1.8V = not regulating, I assumed there could be something wrong with the board). Anyways, initially I posted it as a comment but decided to turn into an answer, either way good luck with the hunt! \$\endgroup\$
    – Wesley Lee
    Jul 12, 2022 at 2:29
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Thanks to some kind person on r/askelectronics, I can now provide an answer to my own question: It is a voltage monitor, which generates a reset signal when the supply voltage drops below 1.67V.

Part number: TPS3839G18DQN

enter image description here

I was (and kind of still am) confused by the wide VDD trace, given that the TPS3839 doesn't require any significant current but I looked through all datasheets I could find for TI-products with this package type/size and this was the only one with a "ZL" marking.

It's also most definitely a TI chip due to the marking style. Most other manufacturers use a dot as a pin 1 marking on this package but TI uses this little bracket. Although I could not find a picture that shows the TPS3839's top, other X2SON/DQN ICs from TI (in this case an LDO) look just like the one on the GoPro's PCB:

enter image description here

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