On 6/11/08, Vasile Surducan <piclist9@gmail.com> wrote:
> One perfect application for TL431 is replacing a few lines of code and
> some comparators and/or AD inputs for monitoring precisely the PIC
> supply value in portable applications. It's what I named "oldest but
> goldest". Like LM723, ICL7107 and a few other components without age
> and without aging.
> :)

TL431 is also widely used in the feedback path of many
isolated Flyback converters together with an opto-coupler.
Be very careful about the caps used with TL431. Back in
1999, one of my colleague wrongly used one cap. The
symptom was that the regulator would not regulate properly
at higher operating temperature and it would trip the secondary
crowbar over-voltage protection circuits and thus caused the
primary fuse to blow. It was a solenoid driver module and
customer found out that the modules would have the fuse blow
after few weeks and the failure all happened during the
switch-on moment. Initially we all thought the inrush current control
circuit was the culprit. In the end, we found out it was due to
a wrong cap used with TL431.

Xiaofan
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