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Every time that I plug my Arduino into the computer, this chip immediately gets burning hot, way too hot to touch, this wasn't something that i noticed happened after a particular event, I just noticed it one day. On the chip it reads "52 TI MSP" I googled this but I couldn't find a datasheet. So what does this chip do? And what could have caused it to break and heat up? I have noticed that the board still works, but is it safe for me to keep using it (for the computer and the rest of the components on the board... and myself)?

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  • \$\begingroup\$ Arduino schematics and layouts are freely available, shouldn't be too hard to figure out. Looks like one half of a dual opamp. \$\endgroup\$ – PlasmaHH Jan 25 '18 at 9:40
  • \$\begingroup\$ Found the schematic of the UNO rev 3 on line: www.arduino.cc/en/uploads/Main/Arduino_Uno_Rev3-schematic.pdf The component is a dual op-amp LMV358IDGKR. I assume you use only the USB cable. I don't see an immediate cause. \$\endgroup\$ – Oldfart Jan 25 '18 at 9:48
  • \$\begingroup\$ @oldfart What could be the reason for it heating up? \$\endgroup\$ – skillz21 Jan 25 '18 at 9:50
  • \$\begingroup\$ As I said ** I don't see an immediate cause.** There could be a dozen causes and for that you need to probe around the boards and have a thorough knowledge of electronics. Debugging is as much an art as it is science. \$\endgroup\$ – Oldfart Jan 25 '18 at 10:33
  • \$\begingroup\$ One thing to check would be if any pins on that chip are shorted to their neighbour due to soldering problems. \$\endgroup\$ – Brian Drummond Jan 25 '18 at 10:54
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According to the Uno rev 3 schematic that part is an LMV358 dual op-amp, it drives the mosfet power selection switch and also drives the "L" LED. https://upload.wikimedia.org/wikipedia/commons/7/7d/Arduino_Uno_Upload.png

It you continue using the board there is a chance the chip will eventually burn even further and potentially cause other problems, in an extreme case the chip might blow its top throwing tiny shrapnel bits around.

The op-amp section that drives the LED has a series 1k resistor, so unless there is a short ahead of the resistor that shouldn't be the problem, but does the LED still flash at times? The other op-amp section drives the gate of a mosfet that selects the main system power source (usb or external).

Mosfets, especially discrete parts, can be very susceptible to damaged from a static zap. During winter months low indoor humidity can greatly increase the potential for static problems. Since one pin of the mosfet connects directly to the usb 5v there is a chance that just the act of plugging and unplugging the usb might have caused a static zap to the Uno board.

If the mosfet's gate became shorted to either the drain or source pin that could easily cause heating of the op-amp chip, (the op-amp's output would then be shorted to one of the power supply lines). Check if the mosfet is also getting hot. The mosfet is the small 3 pin device just to the right of the fuse (which is just below the usb connector in the Uno picture you uploaded).

If you suspect the mosfet is defective you could try removing and/or replacing it, (the mosfet type is listed as an FDN340P.) But if you do take that repair route keep in mind two things, without the mosfet the Uno will only operate when power is supplied from the DC jack. Another issue is that in removing the mosfet there is a chance that just in that process you could damage the part, so if you really want to remove/replace the mosfet do use static protection, (a static wrist strap and even connect the Uno ground to the same ground as the strap). But before doing any component work do check for other obvious problems like shorts or bent pins, also be sure your not shorting something out with other I/O lines too.

If you do decide to try a repair it may be best to just go ahead and replace both the mosfet and op-amp.

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  • \$\begingroup\$ Yes, the L led sometimes flashes really fast for a few seconds and turns off, The small chip next to the op-amp seems to be heating up as well, is that connected to the op-amp as well? It might just be from the heat from the op-amp. \$\endgroup\$ – skillz21 Jan 25 '18 at 12:44
  • \$\begingroup\$ And no, the MOSFET doesn't heat up. \$\endgroup\$ – skillz21 Jan 25 '18 at 12:44
  • \$\begingroup\$ The chips to the left and just below the op-amp are voltage regulators. If there is excess current drain (like due to a shorted mosfet), one or both of those parts might heat up. Most modern regulators will have a limiting function so it would be less likely one of theses would burn out. \$\endgroup\$ – Nedd Jan 25 '18 at 12:47
  • \$\begingroup\$ The mosfet could still be defective even if it is not getting hot, it would depend on the actual type of damage it sustained. \$\endgroup\$ – Nedd Jan 25 '18 at 12:56

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