Author Topic: 3.3V Regulator Not Working On Custom PCB  (Read 1003 times)

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Offline waymond91Topic starter

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3.3V Regulator Not Working On Custom PCB
« on: February 10, 2022, 06:06:08 pm »
Hello,
I just received a custom board assembled from JLCPCB. However, I am having some difficulty with a 3.3V regulator.
Its a little ESP32 board with some I2S and GPS peripherals.
The first board  I actually fired up had a short between 3.3V and ground. After spending an afternoon taking off components and cutting traces, I discovered that there was a short in hole for the mems microphone and the 3.3V pour. On a fresh board I've cut that connection and now I can program the board with my programmer (esp-prog) and power 3.3V directly from that.
However, when I plug in a 1s lipo, no power comes out of the 3.3V regulator. When I plug in USB I only get 0.5v.
Here are my schematic and top layer:

And a link for the pesky part: https://www.lcsc.com/product-detail/Dropout-Regulators-LDO_MICRONE-Nanjing-Micro-One-Elec-ME6217C33M5G_C427602.html
I apologize for the orientation of the VBUS (which is VUSB) line on the schematic...
Any tips on how to diagnose and repair? Should I just ship a different component from digikey, or is likely there is a problem with the PCB itself?
 

Online fourfathom

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Re: 3.3V Regulator Not Working On Custom PCB
« Reply #1 on: February 10, 2022, 06:25:10 pm »
Look at your Pin-3 connection.  You have it "NC" on the schematic and the layout, but on the regulator spec sheet it is "CE", and pin 4 is the NC.  This would certainly explain the regulator being shut down.  This is for the SOT23-5 footprint, which it looks like you are using.
We'll search out every place a sick, twisted, solitary misfit might run to! -- I'll start with Radio Shack.
 
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Offline waymond91Topic starter

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Re: 3.3V Regulator Not Working On Custom PCB
« Reply #2 on: February 10, 2022, 06:51:49 pm »
Wow, thank you so much! Apparently I just looked at the picture in the data sheet, not the table of pin assignments  :palm:
 

Online fourfathom

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Re: 3.3V Regulator Not Working On Custom PCB
« Reply #3 on: February 10, 2022, 08:04:32 pm »
Yeah, that data sheet isn't the best I've ever seen!
We'll search out every place a sick, twisted, solitary misfit might run to! -- I'll start with Radio Shack.
 

Offline waymond91Topic starter

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Re: 3.3V Regulator Not Working On Custom PCB
« Reply #4 on: February 10, 2022, 08:33:41 pm »
Yeah looks like the ins and outs are also in the wrong position, so with any luck I can find a different part that fits
 

Online fourfathom

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Re: 3.3V Regulator Not Working On Custom PCB
« Reply #5 on: February 10, 2022, 08:45:58 pm »
For testing it looks like you can bridge R8 (or replace it with a zero-Ohm resistor), then jumper Pins 3 and 4 (connecting pins 1,3,4 to Vin).  This assumes that pin 4 (NC) is truly not connected to anything internally.  Your pin 2 (ground) and pin 5 (Vout) are connected correctly.
We'll search out every place a sick, twisted, solitary misfit might run to! -- I'll start with Radio Shack.
 
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Offline waymond91Topic starter

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Re: 3.3V Regulator Not Working On Custom PCB
« Reply #6 on: February 10, 2022, 09:18:20 pm »
We did it!
 

Online fourfathom

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Re: 3.3V Regulator Not Working On Custom PCB
« Reply #7 on: February 10, 2022, 10:23:24 pm »
Congratulations!  Now on to the next mystery!
We'll search out every place a sick, twisted, solitary misfit might run to! -- I'll start with Radio Shack.
 


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