Voltage Regulator Electrical Fire?!

Hi all!

I have a PCBA for driving two motors. It consists of a D1-mini (esp8266), 5V LDO voltage regulator (ME6210A50M3G), 2 10µf 0805 capacitors, 40V 3A Schottky diode, 1 N-channel MOSFET, 2 16kΩ 0603 resistors and 2 SOP-8 motor drivers (DRV8871DDAR).

I tested it with no motors attached and just a volt meter, and it worked just fine. I attached two motors and tried it again, and the voltage regulator for the ESP literally exploded and caught fire. Any advice would be great, as I wouldn't want to make that mistake again. I checked the data sheet (linked above), and it seems like it's perfect.

Thanks in advance!

Ohhh.... Slow down. Your presentation is really compact. Lots of facts but not really any strings keeping them together.
I would like to se a wiring of this "smoke generator".

Which motors are they ?
Did you make a schematic ?
A photo of the wiring might also be useful.

For such a project, start with the motors.
Find the stall current of the motors. When a motor is average 250mA, then the stall current can be a few amps.
Then find a motor driver that can supply that stall current.
Then add a Arduino board.

Sorry, just a little flustered. This is my fourth attempt at this project, and I'm getting pretty frustrated. The motors are 12V linear actuators. Here is the specifications:
"Power= 12 Volts DC, max. current draw= 2.5 amps, max. load= 225 pounds, travel speed= 0.39"/min."

Screen Shot 2021-02-19 at 9.42.07 PM.png

Ignore the lower part with the ESP-12F and it's components and wiring.

Screen Shot 2021-02-19 at 9.42.07 PM.png

The drawing is nearly useless. Post a much larger version, and post the details of the motors/actuators and an ENGLISH LANGUAGE version of the motor driver data sheet.

Motors should always be powered by a separate power supply, capable of easily handling the motor stall current. Motors draw the stall current every time they start moving.

I have a PCBA for driving two motors

Did you design the board? If so, consider buying a professionally designed motor driver, like those from Pololu. This task is not for hobbyists.

Rather than a screen capture with some resolution problems, your CAD should allow you to EXPORT your diagram as a jpg image.

Also what your schematic shows is the PCB circuit, not the COMPLETE circuit of your project.
We need to know what you have connected to the plugs and sockets you have in your schematic.

Can you please tell us what the application is, what is the purpose of your project?

Thanks… Tom… :slight_smile:

When you redraw the schematic, please avoid wires crossing over components, and there’s no prize for the smallest drawing in the largest space.

Put more space between parts, wires and annotations.

Admit it... you can only read about half of the image as posted too!

@jremington, only the first page is not English. @TomGeorge, this PCBA is really just a more permanent version for this tutorial I made. Sorry about the schematic. It's late, so I'll fix it up and get back to you tomorrow. Thanks for the response.

for this tutorial I made.

So, you are going to foist this dangerous, failed design on other clueless hobbyists?

Count me out.

@jremington, my tutorial uses a proven to work version of my project using a motor driver bought from amazon, a Arduino uno, and a wemos d1-mini. I was just trying to make it more permanent and cheaper. That tutorial works just fine with no safety issues.

@jremington “this task is not for hobbyists”. Why not? Wouldn’t a simple motor driver chip capable of handling more than the stall current continuously be fine?

It does seem to have more code and hardware than necessary... (I looked at the hackster project site).
There’s nothing wrong with that in itself, but it seems like you published a project that hasn’t been finished yet.
Good luck, I can see what you are trying to do with your driveway requirements, but adding tape on top of glue is rarely the way to develop a product (unless you’re in Chinah)

The schematic in the tutorial looks ok. I’d only look to see if the voltage regulator should have decoupling capacitors and maybe transfer the Nano functions to the ESP.

I can’t read the schematic here but if a 5v regulator is over loaded when 12 volt actuators are added to the circuit, A wiring error is a possible cause.

Can you post EXPORT images of your PCB layout/pattern please?

Thanks.. Tom... :slight_smile:

Here is the PCB pdf. I’m working on the schematic now.

PCB2_PCB_2020-12-11_14-06-44_2021-02-20.pdf (213 KB)

Ops PCB.

Tom... :slight_smile:

Thanks @TomGeorge. The attachment didn't seem to be working properly. Here is the fixed schematic pdf.

Driveway_Schematic.pdf (73.1 KB)

In the schematic the pin VM (motor power supply) on the motor drivers appears connected to Vcc. That can't be right.

Also, nowhere I can find the 12V you talked about in #0.

Major issue with your PCB: there's copper under the ESP12 antenna. That area of the PCB must be kept free from copper (pours and traces); ideally you have the antenna part stick out from the side.

You have plated holes under the buzzer, and the buzzer is even sticking out from the side of the PCB. That's just poor design.

No markings for what appears to be connectors (telling what they are for, and what the polarity is)

I miss mounting holes in that PCB.

I see markings 3V3 and 5V but no 12V, nor can i find regulators (looking for markings Ux and 3-5 pin parts)

With most suppliers you can go up to 100x100mm without extra cost for small runs of PCBs, no reason to cramp it so tiny, especially if you're going to use it for teaching purposes.

OK, as I typed a better schematic appeared. It seems you're using Vcc for the 12V supply. That's confusing to me. So VM to 12V, that'd be correct.

There's a "magnet lock" suggesting electromagnet, without flyback diode on the board.

Do add a 100nF ceramic cap in parallel to the 470µ decoupling for the ESP8266. A general good practice for all ICs. Same for the regulators: it's common to place 100 nF ceramic caps in parallel to the larger caps, even if you intend to use ceramic for the 10µF ones.

That diode between the 5V regulator and its output capacitor looks completely out of place, and will prevent the cap from doing its job properly.

RST from "programming header" is connected directly to GND, which won't do you any good. For normal operation RST should be pulled high, not connected to GND. The ESP12F won't work this way.

The input power supply is a regulated 12V. Thats why the motor driver VM pins are attached to VCC(12V). 5V regulator, 3.3V regulator. Thanks about the antenna. I didn't know that. I made sure that I could put a D1-mini over the top instead if that didn't work. The buzzer is not meant to be soldered to the board. It's meant to be attached to the case, and attached to the PCB with wires. I did forget to add markings for the terminals. I was going to but just forgot.