I am working in a project for getting data from a Load Cell, in the project I use a very good Shield built by a very good friend, this shield has a PGA (Programable Gain Amplifier), a Fast ADC chip, and a voltage regulator (to get 5.0 +/- 0.1 V). This shield is over an Arduino Uno, and when I get a command from Serial port I start getting and printing the time and the load cell voltage data each 1 ms, and this is working pretty nice!.

The Arduino is powered by a 120 AC to 5VDC adapter (see the photo attached), this 5 VDC are elevated to ~8 VDC by a

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LM2587S-DC-DC-Step-Up-Adjustable-Boost-Power-Supply-Module-Converter-Regulator, see this link


this was because of I wasn't able to get a 120 AC to 8 VDC adapter, and these 8 VDC (I need 8 volts for the 5.0 V regulator mentioned above) are plugged into the jack power conector of the Arduino Uno,

The data from the serial port goes to a USB to Serial Rs232 cable converter, this use a PL2303HX chip (look the link down), and this is conected to the pc with a 3 m USB extension


The problem is that this is the second time that I heard something like an electric short and all the things conected to the Serial port is damaged, I mean the PC USB port, the Serial to USB cable Converter, the Arduino (once) and the Arduino serial port (in the other time).

Looking for what happened I opened the USB to Serial Cable and I saw something like a fingerprint of a spark (see the photos attached), and how you can see this happened in the power line. According to this I guess that this was an overvoltage or an overcurrent in the PC usb port, but the other things like mouse and keyboard didn't fail.

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I was wondering if someone could help me to understand what happened, I appreciate any idea.

thanks Thanks for your answers, @Ali_Chen this is a block diagram of my circuit

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I don't need exactly 8 volts, but I need 7 V or more for the power jack to power the Arduino, so I choose 8 volts, I use the booster because I couldn't find more than 5V or 12V adapters, and with the 12V regulator of the arduino gets pretty hot, so I prefer to use the booster.

@Ali Chen I saw that too, that the damage was in the power lines, and for that reason I guess that was an over voltage or over current from the pc USB port, but do you think that too?

@slightlynybbled, I had purchase a better supplier USB-TTL cable from SEED, but I buy it from Digikey,


I know this is not as good as Adafruit once, but I am in Colombia and it is really difficult to get this things because I have to pay for shipment and some taxes when it get into the country

excuse me for all the comments in the same answer.

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    \$\begingroup\$ Please explain why do you need the 8 V supply, and how do you apply it to your setup. Schematics in a block form will help. \$\endgroup\$ Oct 27, 2017 at 0:00
  • \$\begingroup\$ Other peripherals on different ports didn't fail because computer has over-current protection and shuts the USB port down so that it does not damage the controller. I think somewhere your power rails were short and therefore the tragedy. \$\endgroup\$
    – ammar.cma
    Oct 27, 2017 at 2:47

2 Answers 2


Looking at the product that you linked, the USB-to-UART is highly suspect, meaning that you probably have a counterfeit PL2303 device. Counterfeit devices usually work, but with little guarantees.

Please check out the reviews next time. When 'works with windows 7 but not windows 8' and 'drivers no longer available' are in the first few reviews, then the device origin becomes highly suspect!

Try the same thing with something more trusted. Adafruit is well-trusted with the community, try one of theirs. Yes, I realize that it is $18 instead of $7, but isn't that worth your USB port, arduino, and other hardware?

  • \$\begingroup\$ This is clearly a PL2303 device, not FTDI… \$\endgroup\$
    – user39382
    Oct 27, 2017 at 3:00
  • \$\begingroup\$ Of course! Mental reflex. Same applies, though, if you don't have drivers and the device is so cheap as to be nearly unreasonable from a non-qualified vendor... highly suspect. Thank you for the comment, will edit. \$\endgroup\$ Oct 27, 2017 at 10:53

As the picture shows, the damage did occur in the area of pins 18 - 19 - 20 - 21. According to PL2303HX datasheet and application schematics, pin20 is VDD_5V, and pins 18 and 21 are GND. Apparently the overvoltage (8V) [or some other power overload] has occurred, and the internal 5 V (to whatever, 3.3V) LDO regulator failed by shorting VDD to GND. As result a typical "pop-up" and smoke happens, due to overheat and explosion of bond wires.


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