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voltage regulator problem
2

voltage regulator problem

voltage regulator problem

(OP)
Hi all,
I am trying to use a fixed 2.7V voltage regulator (MIC5219-2.7YM5), and the voltage output is 1.4V when I wire it according to the datasheet and supply it with anywhere from 2.5V to more than 5V. When I tried putting a load on it (20K), the voltage drops to almost zero. Any idea why this is? I ordered three of these regulators and got the same result when I tried all of them. Thank you.

RE: voltage regulator problem

You need to include a sketch.
What is the input voltage to the regulator when you load it up?

RE: voltage regulator problem

Only thing I can guess is that Enable is floating or low. Shall be tied high on these regulators.

Gunnar Englund
www.gke.org
--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

RE: voltage regulator problem

Decoupling? I see no capacotors in your diagram.

Did you see any wild HF oscillation on the output?

Gunnar Englund
www.gke.org
--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

RE: voltage regulator problem

Did you thoroughly read the datasheet?  While the Bypass input can be left floating, the output REQUIRES a capacitor to PREVENT oscillation.

TTFN

FAQ731-376: Eng-Tips.com Forum Policies

RE: voltage regulator problem

(OP)
I think I put the decoupling cap on at first, but took it out when it didn't work. I will try again.  I don't see conceptually how not having the decoupling cap would cause the voltage to drop as soon as I put any load on though...can someone explain this to me? Thanks

RE: voltage regulator problem

HF oscillations and their consequences aren't always easy to understand. Could YOU explain why you left it out? Thanks.

Gunnar Englund
www.gke.org
--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

RE: voltage regulator problem

(OP)
because I am an idiot and didn't read the datasheet? haha

RE: voltage regulator problem

OK! That's a good explanation. Does it work now?

Gunnar Englund
www.gke.org
--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

RE: voltage regulator problem

Don't feel too bad Brashear.
Everyone here has at some stage or other in their career, learned a similar lesson.

RE: voltage regulator problem

(OP)
yup, that fixed it! Thanks everyone

RE: voltage regulator problem

That's one good reason for having an oscilloscope handy during integration.  Many odd things can be readily dispensed with if you can actually see what's what.

TTFN

FAQ731-376: Eng-Tips.com Forum Policies

RE: voltage regulator problem

Op Amps found in everthing these days !

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