Author Topic: Identifying SMD by Code  (Read 880 times)

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Offline fanzam

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Identifying SMD by Code
« on: November 17, 2019, 11:55:59 am »
I would like help to identify SMD components, may I ask what is the best practice without having access to the schematics.

I was told that there is a book which can translate package factory code to part number however I tried and cannot find any books online.
I have found websites which give examples however did not manage to find my model

Code                     Package                Part No
FAJ **                   ?????                    ????
6BT24                   SOT-23                 BC817-25

Thanks in advance
Mark
 

Offline tggzzz

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Re: Identifying SMD by Code
« Reply #1 on: November 17, 2019, 12:20:15 pm »
Consider:
  • how many different SMD devices exist
  • how many different codes are available with that number of characters
  • what is the consequence of comparing 1 and 2
There are lies, damned lies, statistics - and ADC/DAC specs.
Glider pilot's aphorism: "there is no substitute for span". Retort: "There is a substitute: skill+imagination. But you can buy span".
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Offline Gyro

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Re: Identifying SMD by Code
« Reply #2 on: November 17, 2019, 12:44:18 pm »
Here are a couple of sites, the first one might be the "book" you are talking about...

http://www.marsport.org.uk/smd/mainframe.htm

http://www.s-manuals.com/smd
Chris

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Offline ataradov

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Re: Identifying SMD by Code
« Reply #3 on: November 17, 2019, 07:04:47 pm »
The small package is SOT-23-5.

I have a few of those PDFs that have some parts listed, but I quite literally never found a single part that I was looking for there.

So the best thing to do is identify the part function and search for something like "SOT-23-5 LDO FA", "SOT-23-5 OpAmp FA", etc.
Alex
 

Offline SiliconWizard

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Re: Identifying SMD by Code
« Reply #4 on: November 17, 2019, 07:19:37 pm »
Finding SMD by marking code is always a bit hit or miss.

But I think it may be this: https://smd.yooneed.one/code4641.html
FAJ
RP170N181B5
Ricoh
SOT-23-5
Linear voltage regulator IC

RP170 series: https://www.e-devices.ricoh.co.jp/en/products/power/vr_ldo/rp170/
 

Offline flolic

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Re: Identifying SMD by Code
« Reply #5 on: November 17, 2019, 07:22:22 pm »
From my book.
 

Offline Yansi

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Re: Identifying SMD by Code
« Reply #6 on: November 17, 2019, 07:37:02 pm »
The small package is SOT-23-5.

I have a few of those PDFs that have some parts listed, but I quite literally never found a single part that I was looking for there.

So the best thing to do is identify the part function and search for something like "SOT-23-5 LDO FA", "SOT-23-5 OpAmp FA", etc.

It is not SOT23-5. Look at the real SOT23 near  it.

This is a SC70, or thereof.
http://ww1.microchip.com/downloads/en/DeviceDoc/5L_SC70_LT_C04-061D.pdf
 
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Offline ataradov

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Re: Identifying SMD by Code
« Reply #7 on: November 17, 2019, 07:44:24 pm »
It is not SOT23-5. Look at the real SOT23 near  it.
This is a SC70, or thereof.

The package nomenclatures confuse me a lot. I just use parts that I've used personally as a reference. I have never seen a part that would be of the same size as your typical 3-pin SOT-23 with 5 pins.

The LDO I use all the time MIC5504-3.3YM5-TR comes in the same small package. The datasheet calls it SOT-23-5. On the digikey it is described as   "Package / Case: SC-74A, SOT-753",  "Supplier Device Package: SOT-23-5".

But calling those smaller packages "SOT-23-5" for search purposes was more useful than not, so I personally will continue to do so.
Alex
 

Offline SiliconWizard

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Re: Identifying SMD by Code
« Reply #8 on: November 17, 2019, 07:51:40 pm »
Some (many) distributors don't help with this, as they often get this wrong as well in their catalogs.

https://en.wikipedia.org/wiki/Small-outline_transistor#SOT23-5,_SOT353

Judging on the pic relative to the other part which is bigger (which we can assume is a SOT23), it's probably a SOT353 instead (note the confusing part is also with the different nomenclatures used between SOT, SC, etc.) which don't help.
 

Offline amyk

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Re: Identifying SMD by Code
« Reply #9 on: November 17, 2019, 07:56:37 pm »
I use the chip.tomsk.ru, which gives plenty of results for FA*. You can search for images with those part numbers and look at the results from people selling the parts, and hopefully find an image match that way.

Note that the 'J' turned 90 degrees is itself an important distinction.
 

Offline Yansi

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Re: Identifying SMD by Code
« Reply #10 on: November 17, 2019, 08:11:39 pm »
It is not SOT23-5. Look at the real SOT23 near  it.
This is a SC70, or thereof.

The package nomenclatures confuse me a lot. I just use parts that I've used personally as a reference. I have never seen a part that would be of the same size as your typical 3-pin SOT-23 with 5 pins.

The LDO I use all the time MIC5504-3.3YM5-TR comes in the same small package. The datasheet calls it SOT-23-5. On the digikey it is described as   "Package / Case: SC-74A, SOT-753",  "Supplier Device Package: SOT-23-5".

But calling those smaller packages "SOT-23-5" for search purposes was more useful than not, so I personally will continue to do so.

It is not that useful, especially when you know it is not true.

SOT23 is always SOT23 size, and there are 3, 5, 6 and even 8 pin variant of it. The plastic body is still the same size (3mm wide). 4 pin variant of SOT23 exists too, but it is called SOT143 and one of the leads is wider.

Do not confuse SOT143 (3mm) with SOT343, that is the smaller brother of it (2mm wide body).

SC70 (2mm wide body also called SOT323) is the smaller brother of SOT23 (3mm wide body). 

SC88 is I think a 5pin variant of SC70,  and SOT363 is sometimes what a 6pin SC70 is called as. 

If not enough confusion already, I think there is even smaller variant of all those, the SOT416 (1.6mm wide body). And all derivates of it.

//EDIT: There is indeed a metric crap ton of SOT23-5 devices sized exactly as SOT23. For example: MCP6001T-I/OT, 74LVC1G14DBV,  .. etc. ... Just look around.

Also please account for manufacturing tolerance of couple tenths of milimeter, with these devices. The sizes mentioned above shall be the nominal ones.
« Last Edit: November 17, 2019, 08:15:38 pm by Yansi »
 

Offline fanzam

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Re: Identifying SMD by Code
« Reply #11 on: November 18, 2019, 12:32:29 am »
Hi all ,

Thanks for your kind reply.

Yansi Is correct this matches my dimensions since 100% it is not sot23-5.
From datasheet I can confirm it is  SC70-5 well done to spot that from the image.

Other hint I have is the silkscreen, FT for me stands for Mosfet but once again I am guessing.

I was hoping that these codes are unique, Trail and error is possible but what I should order to narrow this down.

I have 3 of these that are working fine so I can match with the new part.

Regards
Mark




« Last Edit: November 18, 2019, 12:35:23 am by fanzam »
 

Offline SiliconWizard

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Re: Identifying SMD by Code
« Reply #12 on: November 18, 2019, 02:57:14 am »
The LDO I pointed to was the only one I found with a "FAJ" marking, but I got ahold of its datasheet, and only the SOT23-5 package has a FAJ marking. The datasheet shows this same LDO exists in SC70/SC88 package, so it could have been, but with completely different markings... so, likely nope.

The best candidate so far appears to be what flolic pointed to above:  ELM7SH14TB Schmitt Inverter (vendor: ELM technology). It's a single-gate inverter with Schmitt trigger input. Found the datasheet, and they come in SC-70-5 package, with FA marking, and the J being the lot number (possible values: A to Z), which is why it's marked at 90° probably. Of course it may also be something else. Looking at the circuit around may help figuring if it could at least stand a chance of being this single-gate (from its pin-out).

Datasheet: http://www.elm-tech.com/en/products/logic-ic-hs/elm7sh14xb/elm7sh14xb.pdf

Now I'm trying to figure out what the "FT" in the "FT1" reference could stand for if the part is the above.
« Last Edit: November 18, 2019, 03:08:18 am by SiliconWizard »
 

Offline fanzam

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Re: Identifying SMD by Code
« Reply #13 on: November 18, 2019, 05:45:40 am »
Schmitt Inverter makes more sense then a Mosfet since I am not seeing any application for high amperage on this circuit since all it does control power to switch a relay.
This uses a  Coded Magnetic Sensors in order to switch on / off the relay.

This PCB was designed by a small Company in Italy however all the markings on the PCB are correct , R = Resistor , U = IC and so on, I have never seen FT on a PCB but I am sure it mean something.

Regards
Mark
« Last Edit: November 18, 2019, 05:47:16 am by fanzam »
 

Offline amyk

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Re: Identifying SMD by Code
« Reply #14 on: November 18, 2019, 01:03:30 pm »
FET ? If it's driving the relay, it could be one.
 

Offline fanzam

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Re: Identifying SMD by Code
« Reply #15 on: November 18, 2019, 01:45:05 pm »
Mosfet was my first guess however I cannot find any Mosftet that has this package (SC70-5 or SOT353).
Yes, a mosfet can be used as a trigger switch. Mosfet normally are marked as a normal transistor since they are transistor after all (Q), however I have seen many weird markings on PCB, normally I do not pay attention to silkscreen and I just check the schematic but in this case I do not have it.

I have checked the traces on PCB and notice the coils of the 3 relays are going to a 8ch Darlington Sink Driver (ULN2803APG) so this FT1 , 2 and 3 has nothing to do with relays.
I believe this is more something to do with the Coded Magnetic Sensors circuit to stabilize the voltages.

Thanks once again
Mark




 

« Last Edit: November 18, 2019, 02:19:35 pm by fanzam »
 

Offline fanzam

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Re: Identifying SMD by Code
« Reply #16 on: November 21, 2019, 03:44:41 pm »
Hello ,

I have tried my best to create a schematic without removing any components.

The Coded sensor is 4 wire and 2 of the wires are common.

I have done a Schematic Diagram to understand better the circuit in the hope to get this Part number for FT2.
This FT2 all it does send a signal to the MCU if door is Opened or Closed.

After searching several SMT catalogs I manage to find 1 datasheet with FA part number HD74HCT1G14 however the pinout does not match, my GND is on pin 2 and this one I found is on pin3.

If anyone have any idea what I should do next please let me know since I am stuck with this project.
Thanks in advance

Regards
Mark
 

Offline shakalnokturn

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Re: Identifying SMD by Code
« Reply #17 on: November 21, 2019, 05:22:16 pm »
I'm relaying the tip learnt from someone else out here:
Try the Taobao website searching with package type(s) and all or part of marking code. Photos help to identify.
 

Offline fanzam

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Re: Identifying SMD by Code
« Reply #18 on: November 21, 2019, 05:53:15 pm »
Thanks for your suggestion unfortunately I already tried that with no success.

I found this part number NZF220DFT1G which looks promising.
Shall I try this or I will see Magic smoke ?

At this Stage I cannot measure any voltages or signals since I do not have a working circuit but I can only guess.

Regards
Mark

 

Offline SiliconWizard

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Re: Identifying SMD by Code
« Reply #19 on: November 21, 2019, 07:03:44 pm »
Well, if you're positive pin 2 is connected to GND on your board, and that no voltage exceeds the max rated voltage of this chip, I see no reason for magic smoke. (Well, there could be: pin 3/pin 4 and pin 1/pin 5 will basically get shorted through a ~100 Ohm resistance (approx.) Probably not enough to cause magic smoke at those low voltages though.)
« Last Edit: November 21, 2019, 07:08:58 pm by SiliconWizard »
 

Offline fanzam

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Re: Identifying SMD by Code
« Reply #20 on: November 21, 2019, 07:27:48 pm »
Thanks, I will give it a go and hope this help anyone not to give up.

I am using a www.leuze.com Magnetically coded sensor (€85 x 3), I have found the part number from the sensor Datasheet.


Benefits:
Designed to suppress EMI/RFI Noise in Systems Subjected to Electromagnetic Interference.

Regards
Mark
« Last Edit: November 21, 2019, 07:37:42 pm by fanzam »
 

Offline SiliconWizard

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Re: Identifying SMD by Code
« Reply #21 on: November 21, 2019, 07:35:04 pm »
One thing you could try temporarily, is to replace the chip on the board with two resistors (look at the DS) - of 1kOhm or a bit higher even,  further limiting any risk of mishap, but the circuit should IMO still be working like this. If it does, then it'll be definitely safe to use the reference you found.
 

Offline fanzam

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Re: Identifying SMD by Code
« Reply #22 on: November 21, 2019, 07:42:17 pm »
Thanks for your suggestion, The main PCB has a dead transformer and 1 damaged FT part.
I will buy the required parts and I will take your suggestion to remove the MCU to prevent further damage.

I think FT = FILTER  :)

Regards
Mark
 

Offline SiliconWizard

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Re: Identifying SMD by Code
« Reply #23 on: November 21, 2019, 07:55:55 pm »
I think FT = FILTER  :)

Hmm, now it does make sense indeed! :-+
 


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