help needed to identify sot-23 transistor

[[email protected]]

Hi,

The smd sot-23 transistor is marked as A009. This transistor is used
to control a fan speed in a buck step down converter. The transistor
is breakdown so that the whole 12V is applied on the fan. And I have
no idea what kind of transistor is it MOFSET or PNP

thanks

 

[Eeyore]

Hi,

The smd sot-23 transistor is marked as A009. This transistor is used
to control a fan speed in a buck step down converter. The transistor
is breakdown so that the whole 12V is applied on the fan. And I have
no idea what kind of transistor is it MOFSET or PNP

SMT parts of that size all have very abbreviated markings.

Good luck identifying it.

Graham

 

[nobody]

Hi,

The smd sot-23 transistor is marked as A009. This transistor is used
to control a fan speed in a buck step down converter. The transistor
is breakdown so that the whole 12V is applied on the fan. And I have
no idea what kind of transistor is it MOFSET or PNP

thanks

There is a search engine for surface mount package markings here, but it
is far from complete:

http://www.random-science-tools.com/electronics/SMD_markings.php

There is a site here with quite a few parts, but I couldn't see A009

http://clivetec.superihost.com/SMD_CodesA.htm

Remember that it could be a letter "o" not zero and sometimes the last
digit is the date code, not the device type.

Unfortunately, it is very hard to identify these parts from the code
they aren't even unique so if you do find one which is marked A009, it
may not be the one you want.

Can you work out what it is by looking at the voltages on the three
pins? Does it go between the fan and ground or the fan and +ve?

Good luck.
--

 

[Robert Baer]

Hi,

The smd sot-23 transistor is marked as A009. This transistor is used
to control a fan speed in a buck step down converter. The transistor
is breakdown so that the whole 12V is applied on the fan. And I have
no idea what kind of transistor is it MOFSET or PNP

thanks

It may not be a transistor; it is possible to have the whole switcher
circuitry in a SOT-23 package.
?PNP????

 

[MassiveProng]

It may not be a transistor;

Examination of the surrounding circuitry would prognose that.

it is possible to have the whole switcher
circuitry in a SOT-23 package.
OK.

?PNP????

You know... the opposite of NPN.

 

[Ben Jackson]

There is a search engine for surface mount package markings here, but it
is far from complete:

http://www.random-science-tools.com/electronics/SMD_markings.php

That's very handy. I think I'll go add every SMT part I buy to that
just in case I need to ID them later myself!

 

[Alex]

HI,

I meant bi-polar not PNP. The broken park is marked as Q317 on the
board. The one near by is marked SS which appears to be a MOSFET tr-or
and it is also marked as Q316. So I assume that Q317 is also a tr-or.
And seems like it is packed not into the SOT-23 but into the SOT-323
because it is a little bigger then the Q316

I'm attaching a scheme very sketchy one http://
petergof.googlepages.com/scheme.PNG

Honestly speaking it absolutely make no sense to me. So most probably
I've interpreted something wrong

 

[Alex]

What I'm 100% sure is that 12V is applied now onto the fan. Previously
+5.85V were applied on low load and 9.5V on full load.

 

[Winfield Hill]

I meant bi-polar not PNP. The broken park is marked as Q317 on the
board. The one near by is marked SS which appears to be a MOSFET tr-or
and it is also marked as Q316. So I assume that Q317 is also a tr-or.
And seems like it is packed not into the SOT-23 but into the SOT-323
because it is a little bigger then the Q316

I'm attaching a scheme very sketchy one http://
petergof.googlepages.com/scheme.PNG

Honestly speaking it absolutely make no sense to me. So most probably
I've interpreted something wrong

It looks like a p-channel mosfet transistor to me.

 

[Alex]

It looks like a p-channel mosfet transistor to me.

I also thought about it. But then its source leg shall be on +12 and
not on the ground.

 

[Winfield Hill]

I also thought about it. But then its source leg shall be on +12 and
not on the ground.

Yes, its source leg is at +12, not ground, because it couldn't
work otherwise. It's a common circuit. The sketch is wrong.

 

[Alex]

Yes, its source leg is at +12, not ground, because it couldn't
work otherwise. It's a common circuit. The sketch is wrong.

um, seems like i have to disassemble my computer to perform some
measuring which is a bit of work. But thanks anyway.

 

[nobody]

That's very handy. I think I'll go add every SMT part I buy to that
just in case I need to ID them later myself!

Good idea. If we all did that we may have a chance of identifying these
things.

--

 

[Tom Bruhns]

It looks like a p-channel mosfet transistor to me.

http://www.tkb-4u.com/code/smdcode/indexsmdcode.php is another place
to look for SMT marking codes. They suggest than an A9 in SOT23 may
be a Siliconix SI2309DS, a P-channel mosfet. The Vishay/Siliconix
data sheet says the marking is simply A9, but another manufacturer of
an equivalent part may be marking them A0009. (That's quite a bit to
get on a SOT23, it seems like. Usually the codes are just two or
three characters.)

Cheers,
Tom

 

[Robert Baer]

Examination of the surrounding circuitry would prognose that.




You know... the opposite of NPN.

Almost nobody uses a PNP, especially in a fan controller...

 

[Robert Baer]

HI,

I meant bi-polar not PNP. The broken park is marked as Q317 on the
board. The one near by is marked SS which appears to be a MOSFET tr-or
and it is also marked as Q316. So I assume that Q317 is also a tr-or.
And seems like it is packed not into the SOT-23 but into the SOT-323
because it is a little bigger then the Q316

I'm attaching a scheme very sketchy one http://
petergof.googlepages.com/scheme.PNG

Honestly speaking it absolutely make no sense to me. So most probably
I've interpreted something wrong

Q316, Q317 etc have absolutely *nothing* to do with part type or
function; those are part designators.
The manufacturers PC layout and build kit list would have more info,
like "Q5 NPN 2N2222A,...R23 5K 20Watt".
Even markings *on* a part can be what i call "mouse numbers" meaning
"house numbers" which are not related to what they really are.
A number of large companies use their own internal coding system and
have standard parts marked (by the makers) to their specs.

 

[Alex]

linkis another place
to look for SMT marking codes. They suggest than an A9 in SOT23 may
be a Siliconix SI2309DS, a P-channel mosfet. The Vishay/Siliconix
data sheet says the marking is simply A9, but another manufacturer of
an equivalent part may be marking them A0009. (That's quite a bit to
get on a SOT23, it seems like. Usually the codes are just two or
three characters.)

Cheers,
Tom

Seems like you are right! Thanks a lot Tom!