Hello piclist,

i would like to hear from someone that uses this DC/DC chip, and problems
that found using it.
The good thing about it is that it has a Switching input, and also has a
Linear regulator inside. All in one chip, and two different inputs. Its of
great help.

#
I've found problems when starting the chip, with the Switching regulator.
Prior to power up, when the output voltage is less than ~1.5V the regulator
sits on 2V output. If on that moment i take batteries off, anf then on
again, the regulator jumps to my desired 5V output.
It only regulates fine on 5V output, if prior to power-up, the output is
bigger than ~1.5V.   wierddd...
When erroneously sitting at 2V, I noticed that if i touch pin 4 (Switching
current control) with a srewdrive, or a wire, the regulator sudenly jumps.
It seems it needs some noise on that pin to start up correctly ?

#
The Liner regulator works fine.

Has anyone found this problem, or know how to solve it ??


Besides this Texas TL499, anyone know another that has this characteristics
inside of it, the two different regulators  ??

Looking forward for your replies.
Kind regards,

Antonio Sergio Sena


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