There's cheap and then there's cheap...

I been doing a lot of work with PLC It's really fun work because it's mostly handing led lighting and and the car wash motors and brushes. But at ClydeCrashKop I get a lot of they don't no what there talking about.
I been doing control work a long time I'm glade I have it's easy work the older I get LOL.

Today I had the joy to fix what my co worker's been trying to get to work for weeks

dknguyen said:

What microcontroller is designed for use with a transformerless power supply?

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Microchip's PIC micros.


Transformerless power supplies are instrumental in keeping costs low in microcontroller-based applica- tions powered from a wall receptacle. Both resistive and capacitive power supplies offer substantial cost and space savings over transformer-based and switch- based supplies. Capacitive power supplies offer an energy efficient solution, while resistive power supplies offer increased cost savings.


https://ww1.microchip.com/downloads/en/appnotes/00954a.pdf
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gophert said:

Microchip's PIC micros.


Transformerless power supplies are instrumental in keeping costs low in microcontroller-based applica- tions powered from a wall receptacle. Both resistive and capacitive power supplies offer substantial cost and space savings over transformer-based and switch- based supplies. Capacitive power supplies offer an energy efficient solution, while resistive power supplies offer increased cost savings.

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How is it designed for it though?

dknguyen said:

How is it designed for it though?

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How is it NOT designed for it? Ask the author of the Microchip App Note why it works (a stupid question from my point of view), or ask the author of the referenced datasheet at the beginning of this thread to understand how a microcontroller can specifically not work with transformerless power supplies (also a stupid question because there is nothing special about the power from a transformerless supply).

gophert said:

How is it NOT designed for it? Ask the author of the Microchip App Note why it works (a stupid question from my point of view), or ask the author of the referenced datasheet at the beginning of this thread to understand how a microcontroller can specifically not work with transformerless power supplies (also a stupid question because there is nothing special about the power from a transformerless supply).

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Function was never the question. Safety was, and the lack of isolation was the entire point of the initial comment about the warning.

dknguyen said:

Function was never the question. Safety was, and the lack of isolation was the entire point of the initial comment about the warning.

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The question I addressed was.which (if any) microcontroller manufacturer would recommend transformerless supplies. My answer was, Microchip, for one. Not everyone agrees with the blanket statement that transformerless power supplies are too dangerous to use.

I think the only statement that I have ever seen that says, "do not use transformerless power supplies" was on allaboutcircuits.com and the datasheet of the cheap microcontroller that is the subject of this thread.