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SMD code BW in SOD-123

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 13 parts are ranked, with a meter test that settles it. It works on a dead part too.

  • LBZT52MB15T1GSOD-123Zener diode, 2 pins, LRCZener diode2 pinsLRC
    What it is
    Zener diode
    Maker
    LRC
    Package
    SOD-123
    Pins
    2
    Details
    Zener diode, VZ Min 14.7 V, VZ Max 15.3 V, Vz@IZT mA 5
    Source
    Manufacturer datasheet

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

  • S-LBZT52MB15T1GSOD-123Zener diode, 2 pins, LRCZener diode2 pinsLRC
    What it is
    Zener diode
    Maker
    LRC
    Package
    SOD-123
    Pins
    2
    Details
    Zener diode, VZ Min 14.7 V, VZ Max 15.3 V, Vz@IZT mA 5
    Source
    Manufacturer datasheet

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

  • 11 more parts have no package on record. Nothing rules them out, so they stay.
    • CDBQC0530L-HFSchottky diode, ComchipSchottky diodeNot recordedComchip
      What it is
      Schottky diode
      Maker
      Comchip
      Package
      Not recorded
      Pins
      Not recorded
      Details
      30 V, 0.5 A Schottky barrier diode
      Source
      Manufacturer datasheet

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

    • KRX208EDigital 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.

    • KRX208UDigital 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.

    • LFM0530-T1006Schottky diode, Formosa MicrosemiSchottky diodeNot recordedFormosa Microsemi
      What it is
      Schottky diode
      Maker
      Formosa Microsemi
      Package
      Not recorded
      Pins
      Not recorded
      Source
      Manufacturer datasheet

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

    • VS6V0UA1VWMTVS diode, ROHMTVS diodeNot recordedROHM
      What it is
      TVS diode
      Maker
      ROHM
      Package
      Not recorded
      Pins
      Not recorded
      Details
      Transient Voltage Suppressor
      Source
      Manufacturer datasheet

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

    • VS6V0UA1VWMTFTVS diode, ROHMTVS diodeNot recordedROHM
      What it is
      TVS diode
      Maker
      ROHM
      Package
      Not recorded
      Pins
      Not recorded
      Details
      Transient Voltage Suppressor
      Source
      Manufacturer datasheet

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

    • 2SA2018HPNP transistor, ROHMPNP transistorNot recordedROHM
      What it is
      PNP transistor
      Maker
      ROHM
      Package
      Not recorded
      Pins
      Not recorded
      Details
      Si-pnp: Sw, 15V, 500mA, 150mW, B=270..680, 260MHz
      Source
      Published code list

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

    • BU46K302GVoltage supervisor, ROHMVoltage supervisorNot recordedROHM
      What it is
      Voltage supervisor
      Maker
      ROHM
      Package
      Not recorded
      Pins
      Not recorded
      Details
      Voltage detector IC: 3.0V±1%, -Reset PPO, Rdt=200ms
      Source
      Published code list

      Is it dead? The meter test is below: Integrated circuit.

    • SMD15KPA75CATVS diode, MDE SemiconductorTVS diodeNot recordedMDE Semiconductor
      What it is
      TVS diode
      Maker
      MDE Semiconductor
      Package
      Not recorded
      Pins
      Not recorded
      Details
      Transient voltage supressor: Vrwm=75.0V, Vbr=83.80V, Vcl=122.0V, Ipp=123.8A, 15000W(1ms), Bidir.
      Source
      Published code list

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

    • SMD30KPA66CATVS diode, MDE SemiconductorTVS diodeNot recordedMDE Semiconductor
      What it is
      TVS diode
      Maker
      MDE Semiconductor
      Package
      Not recorded
      Pins
      Not recorded
      Details
      Transient voltage supressor: Vrwm=66.0V, Vbr=73.7V, Vcl=107.0V, Ipp=283.2A, 30000W(1ms), Bidir.
      Source
      Published code list

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

    • SMP22TVS diode, VishayTVS diodeNot recordedVishay
      What it is
      TVS diode
      Maker
      Vishay
      Package
      Not recorded
      Pins
      Not recorded
      Details
      Transient voltage supressor: Vbr=24.4..29.8V, Vrwm=22V, Ipp=10.2A, 400W(1ms)
      Source
      Published code list

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

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.

Zener diode

Diode range for the forward check, part lifted, red probe on the anode. A bench supply for the Zener voltage.

Working, it reads

About 0.6 to 0.8 V forward and open in reverse on the diode range. Its Zener voltage shows only on a supply: feed it through a resistor that sets about 5 mA, cathode to positive, read quickly, and it should hold near its rated voltage.

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, forward too: failed open.
  • Holds well off its rated voltage on the supply test: drifted.
  • A soft knee, or a voltage that creeps on the supply test: 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 meter's diode range stops at about 2 to 3 V, so almost every Zener reads open in reverse on it, good or bad; a 3 V meter may just show a 2.4 or 2.7 V part. Above about 3 V the meter cannot tell a Zener from a plain diode.

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.

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.

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.

PNP transistor

Diode range, part lifted or its base leg off the pad.

Working, it reads

Black probe on the base reads about 0.6 to 0.75 V to the emitter and to the collector, and open the other way round. Collector to emitter reads open both ways.

Dead, it reads

  • Collector to emitter the same both ways, near 0 V with a continuous beep: shorted. The commonest failure.
  • The base the same both ways to another pin, near 0 V or a middling value: a shorted junction.
  • Only one junction reads, or none: a junction has failed open. It then looks like a diode.
  • A reading the wrong way round, where it should be open: 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 pair of diodes with a common pin reads just like a transistor, and some transistors carry a built-in diode or resistor. The datasheet says which.

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

Integrated circuit

Voltage with the board powered; ohms from each pin to ground with it off.

Working, it reads

Supply pin at its voltage and the output doing what the datasheet says. Readings between pins depend on the part.

Dead, it reads

  • A pin near 0 Ω to ground or to the supply pin where an identical part does not read that: failed short.
  • Supply present, output stuck: failed, or its load has.
On the board:
A pin shorted to ground on the board can be anything on that net. Lift the pin to be sure.
Compare:
The surest reference is the same IC on a working board, measured pin by pin.
Watch for:
Its protection diodes can read like junctions between pins, even like a transistor. That proves nothing either way.

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 BW

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

Codes that begin with BW

For a marking with its end worn or burnt off. Each code has a page of its own.

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