A similar discussion in Microchip Forum.

http://forum.microchip.com/tm.asp?m=119828

The following is the answer is from J_doin, a very experienced
electronics engineer and a PIC expert.

Regards,
Xiaofan


http://forum.microchip.com/tm.asp?m=119828&mpage=3&key=

 RE: J_doin and company, What's the ... (in reply to xiaofan)
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You are completely right, of course. This thread started with many
very clear statements against AN521.

In another thread, discussion of the infamous AN954 - resistive
transformerless supply triggered a host of warnings by forum members,
pointing out the various safety hazards and reliability issues that
both ApNotes failed to mention.

I agree that both ApNotes are incredibly misleading. A complete
reliability discussion should be included in the ApNotes, and resistor
failure modes should be analysed more carefully. Actually, in the
AN521 the author seems to have no knowledge of the concept of
reliability and failure analysis. I completely agree that it should be
removed from MCP site, along with AN954.

Unexperienced developers might risk their lives, and even design
hazardous equipment that can risk the end users' lives.

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