Login Join Maker Pro
Or sign in with

# Help identifying unknown component (SMD Diode?)

#### Protonus

Feb 18, 2015
9
Hey folks, hoping someone can help identify this component. It's from an AeroForce Technology Inc., brand automotive gauge. I believe it to be damaged, there was a nearby burned/lifted/broken trace (visible at the bottom left edge of the photo), from a botched DIY install by a close friend.

I've attached a high res macro photo of the component and markings.

Written on it is the part number 3LIVP, and what I think is a rating of 18A ? I believe the brand identity is sideways and is a logo of LF?

It's about 7x6x2mm in size.

The component location board marking looks like D, or DI to me?

I think this is a SMD diode? Rated for 18A? And that thick line at one end is the cathode mark? Not sure. I'm not very good at component recognition, sorry.

Can anyone confirm what this is? Package type, size, rating etc, or better yet provide a datasheet? I tried all the links in the pinned thread and I've been googling all I can think to.

Thank you very much in advance!

#### Protonus

Feb 18, 2015
9
Forgot to mention, it tests 1.5 MOhm Anode to Cathode assuming that's an alignment mark, but the other direction is open/infinite resistance. Made me think fried diode?

#### 73's de Edd

Aug 21, 2015
3,477
I'm not seeing any foil path on the viewable side shown . . .excluding the groundplane . . .that is being 18 amp worthy.
Otherwise that seems to be one hefty Littlefuse TVS diode, in SMD casing, with AFT's house numbering on it and should read open circuit.
And if its working with automotive 12 VDC, seems like 18V might be a likely conduction threshold.

Last edited:

#### dorke

Jun 20, 2015
2,342
Let me start by saying that SMD markings are a true pain in the a.

LF is the marking logo of Little-Fuse ,part marking is 18A,
it is a Uni-directional 18V/400W TVS diode P4SMA18A
,here is the datsheet

It could be(less likely ) the 600W P6SMB18A.

Here we have an example of ambiguity of marking from the same manufacture !
(from different ones, is the standard case) ,18A marking 2 possible devices

BTW,
1.The line is the cathode marking.
2.Yes it is fried,if you checked it out of circuit!
3."It's about 7x6x2mm in size."
Please be more accurate,it may help decide which of the 2 possible parts it is,see the datasheets.

Last edited:

#### Alec_t

Jul 7, 2015
3,331
18A marking 2 possible devices
Very confusing. However, the package size is bigger for the higher wattage device.

#### kellys_eye

Jun 25, 2010
5,495
It will measure 'open-circuit' under normal test conditions - goes 'short' under over-voltage situations, as it should.

#### Protonus

Feb 18, 2015
9
Hey everybody, I finally got around to fixing this gauge the other day. So first of all, thank you all so very much, for helping me identify that part! I learned a lot in the process, and truly appreciate it!

I was able to jump the burned/lifted trace with a wire, and I soldered in a "P4SMA18A" as suggested above, to replace the fried diode. The replacement part was a bit physically smaller as you'll see, so perhaps it was not the exact right replacement - but the values were similar enough and well... it's been working great, so I think it was ok!

Thanks again!

#### 73's de Edd

Aug 21, 2015
3,477
YEA ! ! ! . . . . . .PROTRONS rule . . . . . . Vis . . .a . . . .vis . . . mere electrons . . .

73's de Edd

Last edited by a moderator:

#### kellys_eye

Jun 25, 2010
5,495
YEA ! ! ! . . . . . .PROTRONS rule . . . . . .
Bah.... Vote ELECTRONS for 2020......

Last edited by a moderator:

Replies
11
Views
1K
Replies
3
Views
594
Replies
6
Views
54
Replies
7
Views
162
Replies
3
Views
339