I have a LED strip and an ESP8266-12 to control it. As the LEDs need 5V I'm using an AMS1117 3.3V linear regulator to get the 3.3V needed for the ESP8266. The circuit works fine but when I try to establish a serial connection to the ESP by connecting an USB-TTL-Adapter the AMS1117 starts to overheat and breaks in the end.

My circuit

The regulator starts to burn when the circuit is running and I connect the ground-cabel of the serial-adapter to the ESP. I'm new to electronics, so I don't know what happens here. Is there a big current floating from my laptops-USB through the regulator to the power-supply? How can I protect the regulator and prevent it from overheating?

  • 1
    \$\begingroup\$ Make sure you have wired it correctly. Remember, the pins are ordered Vin/Vout/GND, not Vin/GND/Vout like many regulators. \$\endgroup\$ – Tom Carpenter Jan 15 '17 at 19:00
  • 1
    \$\begingroup\$ The AM1117 is only capable of supplying 335mA, the ESP8266 may be using more current, depending on what you are doing with GPIO13 (assuming its on/off, but are you sinking current?). Can you elaborate on what GPIO13 does? \$\endgroup\$ – Ron Beyer Jan 15 '17 at 19:15
  • 1
    \$\begingroup\$ If connecting the ground cable between the laptop and your assembly is causing problems, then these two systems disagree about what "ground" is. The most likely suspect is a problem with your LED power supply and that needs to be solved immediately as it may indicate faults which pose electrocution hazards. It is also possible that your laptop power supply has issues, though obviously if you are running the laptop on battery and the only connection between it and the system is your TTL cable, then the issue would need to be a wiring mistake there. Make sure your TTL cable is 3.3V not 5V. \$\endgroup\$ – Chris Stratton Jan 15 '17 at 19:32
  • \$\begingroup\$ I'm aware of the pinout. The circuit works fine if I don't touch it. Only when I connect the ground, the regulator starts overheating immediately. I have a bench-power-supply with earth-ground-plug. I've measured the Ground of the LED-Power-Supply against earth. No difference. TTL is set to 3.3V. \$\endgroup\$ – kielnino Jan 15 '17 at 19:42
  • \$\begingroup\$ I'm also thinking that they disagree about what "ground" is. But how can I solve this? I expirenced the same with an ESP powered via AMS1117 by a phone charger (5V). When I connected my scope's ground and probe to measure the ESPs output the regulator started overheating immediately after the ground was connected. \$\endgroup\$ – kielnino Jan 15 '17 at 19:54

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Browse other questions tagged or ask your own question.