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SMD code BF in SMA

Marking codes are not standardised, and the same code is reused by unrelated makers for unrelated parts. Below is every part in our tables printed with it, and any printed with a code that is easy to misread as it, from the manufacturers' own marking tables and published code lists.

Not sure which one you have?

Answer up to 4 quick questions and these 43 parts are ranked, with a meter test that settles it. It works on a dead part too.

  • SMAJ13SMATVS diode, 2 pins, DOWOTVS diode2 pinsDOWO
    What it is
    TVS diode
    Maker
    DOWO
    Package
    SMA
    Pins
    2
    Source
    Manufacturer datasheet

    Is it dead? The meter test is below: TVS or ESD protection diode.

  • EC76SMAJ13SMATVS diode, 2 pins, E-CMOSTVS diode2 pinsE-CMOS
    What it is
    TVS diode
    Maker
    E-CMOS
    Package
    SMA
    Pins
    2
    Details
    Transient voltage supressor: Vbr=14.4..17.6V, Vrwm=13V, Ipp=16.8A, 400W(1ms)
    Source
    Published code list

    Is it dead? The meter test is below: TVS or ESD protection diode.

  • P4SMA20SMATVS diode, 2 pins, FagTVS diode2 pinsFag
    What it is
    TVS diode
    Maker
    Fag
    Package
    SMA
    Pins
    2
    Source
    Published code list

    Is it dead? The meter test is below: TVS or ESD protection diode.

  • P4SMAJ13SMATVS diode, 2 pins, Shanghai Lunsure Electronic TechnologyTVS diode2 pinsShanghai Lunsure Electronic Technology
    What it is
    TVS diode
    Maker
    Shanghai Lunsure Electronic Technology
    Package
    SMA
    Pins
    2
    Details
    TVS: 13V, 16.8A, 400W (1ms)
    Source
    Published code list

    Is it dead? The meter test is below: TVS or ESD protection diode.

  • TSMA20SMATVS diode, 2 pins, VishayTVS diode2 pinsVishay
    What it is
    TVS diode
    Maker
    Vishay
    Package
    SMA
    Pins
    2
    Details
    Transient voltage supressor: Vbr=18.0..22.0V, Vrwm=16.2V, Ipp=14A, 400W(1ms)
    Source
    Published code list

    Is it dead? The meter test is below: TVS or ESD protection diode.

  • TV04A130KSMA2 pins, ComchipNot recorded2 pinsComchip
    What it is
    Not recorded
    Maker
    Comchip
    Package
    SMA
    Pins
    2
    Details
    TVS: 13V, 10%, 16.8A, 400W(1ms)
    Source
    Published code list

    Is it dead? The meter test is below: TVS or ESD protection diode.

  • TV04A130K-GSMATVS diode, 2 pins, ComchipTVS diode2 pinsComchip
    What it is
    TVS diode
    Maker
    Comchip
    Package
    SMA
    Pins
    2
    Details
    Transient voltage supressor: Vrwm=13.0V, Vbr=14.40..17.60V, Ipp=16.81A, 400W(1ms)
    Source
    Published code list

    Is it dead? The meter test is below: TVS or ESD protection diode.

  • 8 more parts have no package on record. Nothing rules them out, so they stay.
    • ACDBQC54-HFSchottky diode, ComchipSchottky diodeNot recordedComchip
      What it is
      Schottky diode
      Maker
      Comchip
      Package
      Not recorded
      Pins
      Not recorded
      Details
      30 V, 0.2 A Schottky barrier diode
      Source
      Manufacturer datasheet

      Is it dead? The meter test is below: Schottky diode.

    • ACDBUC54-HFSchottky diode, ComchipSchottky diodeNot recordedComchip
      What it is
      Schottky diode
      Maker
      Comchip
      Package
      Not recorded
      Pins
      Not recorded
      Details
      30 V, 0.2 A Schottky barrier diode
      Source
      Manufacturer datasheet

      Is it dead? The meter test is below: Schottky diode.

    • CDBQC54-HFSchottky diode, ComchipSchottky diodeNot recordedComchip
      What it is
      Schottky diode
      Maker
      Comchip
      Package
      Not recorded
      Pins
      Not recorded
      Details
      30 V, 0.2 A Schottky barrier diode
      Source
      Manufacturer datasheet

      Is it dead? The meter test is below: Schottky diode.

    • CDBU54-HFSchottky diode, ComchipSchottky diodeNot recordedComchip
      What it is
      Schottky diode
      Maker
      Comchip
      Package
      Not recorded
      Pins
      Not recorded
      Details
      30 V, 0.2 A Schottky barrier diode
      Source
      Manufacturer datasheet

      Is it dead? The meter test is below: Schottky diode.

    • CDBUR54-HFSchottky diode, ComchipSchottky diodeNot recordedComchip
      What it is
      Schottky diode
      Maker
      Comchip
      Package
      Not recorded
      Pins
      Not recorded
      Details
      30 V, 0.2 A Schottky barrier diode
      Source
      Manufacturer datasheet

      Is it dead? The meter test is below: Schottky diode.

    • KDS112ESwitching diode, KECSwitching diodeNot recordedKEC
      What it is
      Switching diode
      Maker
      KEC
      Package
      Not recorded
      Pins
      Not recorded
      Source
      Manufacturer datasheet

      Is it dead? The meter test is below: Silicon diode.

    • KRX207EDigital transistor (resistors built in), KECDigital transistor (resistors built in)Not recordedKEC
      What it is
      Digital transistor (resistors built in)
      Maker
      KEC
      Package
      Not recorded
      Pins
      Not recorded
      Source
      Manufacturer datasheet

      Is it dead? The meter test is below: Digital transistor.

    • 2SK3719BF3 pins, RenesasNot recorded3 pinsRenesas
      What it is
      Not recorded
      Maker
      Renesas
      Package
      Not recorded
      Pins
      3
      Source
      Published code list

      Is it dead? The meter test is below: This part.

Is it dead? One meter test per kind

Parts of the same kind are tested the same way, so each test is here once. Each part above points to its own.

TVS or ESD protection diode

Diode range, from the protected line to ground, part lifted if you can.

Working, it reads

A one-way part reads about 0.6 to 0.8 V forward and open in reverse. A two-way part reads open both ways. Arrays with several lines read as the datasheet's diagram draws them.

Dead, it reads

  • From the line to ground, the same reading both ways, near 0 V with a continuous beep: shorted.
  • A reading both ways on a one-way part: leaky.
  • A one-way part open both ways: failed open.
On the board
, a line reading shorted to ground can be this part or anything else on that line. Lift it: if the short goes with it, it has failed.
Compare:
The same part on the next line or connector pin is the healthy reading to compare with.
Watch for:
A two-way part reads open both ways when it is good, exactly like one that has failed open. The meter cannot tell them apart; an identical part on the next line can.

A dead part still carries its marking. A short or an open says it has failed, not that it is a different part.

Schottky diode

Diode range, part lifted or one leg off the pad. Red probe on the anode.

Working, it reads

About 0.15 to 0.45 V anode to cathode, roughly half a silicon diode, and open the other way.

Dead, it reads

  • The same reading both ways round, near 0 V with a continuous beep or the same middling value: shorted.
  • A reading the wrong way round as well: leaky.
  • Open both ways: failed open.
On the board
this is a first look only: the meter reads every path between those pins, and a short can be a neighbour. Lift one leg before you condemn it.
Compare:
If an identical part sits elsewhere on the board, measure it the same way: that is what this one should read.
Watch for:
A large Schottky can read about 0.1 V forward and beep like a short, and leaks a little the wrong way when good, more when warm. It is shorted only if it reads the same both ways. Measure it cold, beside an identical cold one.

A dead part still carries its marking. A short or an open says it has failed, not that it is a different part.

Silicon diode

Diode range, part lifted or one leg off the pad. Red probe on the anode.

Working, it reads

About 0.5 to 0.8 V anode to cathode, and open the other way. Small switching diodes read about 0.6 to 0.7 V; large rectifiers can read a little lower.

Dead, it reads

  • The same reading both ways round, near 0 V with a continuous beep or the same middling value: shorted.
  • Open both ways: failed open.
  • A reading the wrong way round as well: leaky.
On the board
this is a first look only: the meter reads every path between those pins, and a short can be a neighbour. Lift one leg before you condemn it.
Compare:
If an identical part sits elsewhere on the board, measure it the same way: that is what this one should read.
Watch for:
A three-pin body can hold two diodes. With a common pin they read two junctions from that pin, just like a transistor; in series they read two drops end to end. Test each pair the datasheet names.

A dead part still carries its marking. A short or an open says it has failed, not that it is a different part.

Digital transistor

Ohms range, part lifted. The datasheet gives the built-in resistors: R1 in series with the base, R2 from base to emitter.

Working, it reads

Base to emitter reads about R1 plus R2 either way round, about 20 kΩ on a 10 k and 10 k part, give or take their wide tolerance. Collector to emitter reads open. A part with no R2 reads a junction behind R1 one way instead.

Dead, it reads

  • Collector to emitter the same both ways, near 0 Ω with a continuous beep: shorted.
  • From the base, open or far above R1 plus R2: R1 has failed. Static damage shows here most often.
  • Base to emitter near 0 Ω: failed short.
On the board
this is a first look only: the meter reads every path between those pins, and a short can be a neighbour. Lift one leg before you condemn it.
Compare:
The readings depend on the resistor values, so an identical part elsewhere on the board is the surest reference. Measure it the same way.
Watch for:
On the diode range a good part with 10 kΩ resistors reads open on every pair, so a good part looks dead there. Use the ohms range.

A dead part still carries its marking. A short or an open says it has failed, not that it is a different part.

This part

Diode range and ohms range, part lifted.

Working, it reads

Depends on what it is. The datasheet, or an identical part, says.

Dead, it reads

  • Between two pins, the same reading both ways, near 0 V with a continuous beep: shorted.
  • Open between every pair of pins: failed open, or a part that reads open when working.
On the board
this is a first look only: the meter reads every path between those pins, and a short can be a neighbour. Lift one leg before you condemn it.
Compare:
If an identical part sits elsewhere on the board, measure it the same way: that is what this one should read.

A dead part still carries its marking. A short or an open says it has failed, not that it is a different part.

Printed with a code easy to misread as BF

One character differs, and it is one that is easy to confuse under a lamp. Each code has a page of its own.

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