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SMD code WMs in SOT-416

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.

The last letter, s, is lower case, which on NXP and Philips parts is a date or factory code, so it was set aside and WM was searched.

1 part in SOT-416 is printed WMs

Not sure which one you have?

Answer up to 4 quick questions and these 16 parts are ranked, with a meter test that settles it. It works on a dead part too.

  • BCR183TSOT-416Digital transistor (PNP, resistors built in), 3 pins, InfineonDigital transistor (PNP, resistors built in)3 pinsInfineon
    What it is
    Digital transistor (PNP, resistors built in)
    Maker
    Infineon
    Package
    SOT-416
    Pins
    3
    Details
    pnp dig 50V 10k+10k
    Source
    Published code list

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

  • 14 more parts have no package on record. Nothing rules them out, so they stay.
    • SMAFJ7.0CATVS diode, Blue RocketTVS diodeNot recordedBlue Rocket
      What it is
      TVS diode
      Maker
      Blue Rocket
      Package
      Not recorded
      Pins
      Not recorded
      Source
      Manufacturer datasheet

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

    • SMAHFL7.0CATVS diode, Formosa MicrosemiTVS diodeNot recordedFormosa Microsemi
      What it is
      TVS diode
      Maker
      Formosa Microsemi
      Package
      Not recorded
      Pins
      Not recorded
      Source
      Manufacturer datasheet

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

    • SMF7.0CA-MFLTVS diode, Formosa MicrosemiTVS diodeNot recordedFormosa Microsemi
      What it is
      TVS diode
      Maker
      Formosa Microsemi
      Package
      Not recorded
      Pins
      Not recorded
      Source
      Manufacturer datasheet

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

    • TBZT52B18HEZener diode, Galaxy MicroelectronicsZener diodeNot recordedGalaxy Microelectronics
      What it is
      Zener diode
      Maker
      Galaxy Microelectronics
      Package
      Not recorded
      Pins
      Not recorded
      Details
      18V, 500mW, Surface Mount Zener Diodes
      Source
      Manufacturer datasheet

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

    • 74LVC1G06FS3Diodes IncorporatedNot recordedNot recordedDiodes Incorporated
      What it is
      Not recorded
      Maker
      Diodes Incorporated
      Package
      Not recorded
      Pins
      Not recorded
      Details
      CMOS logic IC: Inverter (ODO)
      Source
      Published code list

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

    • 74LVC1G07FS3Diodes IncorporatedNot recordedNot recordedDiodes Incorporated
      What it is
      Not recorded
      Maker
      Diodes Incorporated
      Package
      Not recorded
      Pins
      Not recorded
      Details
      CMOS logic IC: Noninverting buffer/driver (ODO)
      Source
      Published code list

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

    • AX5505R29DC-DC converterDC-DC converterNot recordedNot recorded
      What it is
      DC-DC converter
      Maker
      Not recorded
      Package
      Not recorded
      Pins
      Not recorded
      Details
      Micropower VFM Synchronous Step-up DC/DC Converter
      Source
      Published code list

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

    • BCR183L3Digital transistor (PNP, resistors built in), InfineonDigital transistor (PNP, resistors built in)Not recordedInfineon
      What it is
      Digital transistor (PNP, resistors built in)
      Maker
      Infineon
      Package
      Not recorded
      Pins
      Not recorded
      Details
      Si-pnp-Digi: Sw, 50V, 100mA, 250mW, R1/R2=10k/10k, 130MHz
      Source
      Published code list

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

    • BD46291GVoltage supervisor, ROHMVoltage supervisorNot recordedROHM
      What it is
      Voltage supervisor
      Maker
      ROHM
      Package
      Not recorded
      Pins
      Not recorded
      Details
      CMOS-IC: Voltage Detector 2,9V, -Reset Push-pull output, 100ms
      Source
      Published code list

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

    • LT4ME64CATVS diode, Lite-On SemiconductorTVS diodeNot recordedLite-On Semiconductor
      What it is
      TVS diode
      Maker
      Lite-On Semiconductor
      Package
      Not recorded
      Pins
      Not recorded
      Details
      Transient voltage supressor: Vrwm=64V, Vbr=71.1..78.6V, Ipp=3.9A, 400W(1ms), Bidir.
      Source
      Published code list

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

    • MIC2211-1.6/2.8BMLLDO regulator, MicrelLDO regulatorNot recordedMicrel
      What it is
      LDO regulator
      Maker
      Micrel
      Package
      Not recorded
      Pins
      Not recorded
      Details
      Linear voltage regulator IC: LDO, Dual out, Vo1/Vo2=1.6V(150mA)/2.8V(300mA)±1%, +CE
      Source
      Published code list

      Is it dead? The meter test is below: Voltage regulator.

    • RP300K42DCVoltage supervisor, RicohVoltage supervisorNot recordedRicoh
      What it is
      Voltage supervisor
      Maker
      Ricoh
      Package
      Not recorded
      Pins
      Not recorded
      Details
      Voltage detector IC: 4.2V±1%, +Reset PPO, -MR, Rdt=200ms
      Source
      Published code list

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

    • S-1315D27-A6T2U36 pins, ABLICNot recorded6 pinsABLIC
      What it is
      Not recorded
      Maker
      ABLIC
      Package
      Not recorded
      Pins
      6
      Details
      equivalent [2.7V LDO]
      Source
      Published code list

      Is it dead? The meter test is below: Voltage regulator.

    • SMAS7.0CATVS diode, Formosa MicrosemiTVS diodeNot recordedFormosa Microsemi
      What it is
      TVS diode
      Maker
      Formosa Microsemi
      Package
      Not recorded
      Pins
      Not recorded
      Details
      Transient voltage supressor: Vrwm=7.0V, Vbr=7.78..8.60V, Ipp=33.3A, 400W(1ms), Bidir.
      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.

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.

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.

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.

Voltage regulator

Voltage, board powered, black probe on ground. Then ohms with the power off.

Working, it reads

Input pin at the supply, output pin at its rated voltage, and the enable pin high if it has one.

Dead, it reads

  • Output equal to the input: the pass element has shorted. Everything after it may have taken the full input.
  • Input present, enable high, no output: failed open, or holding itself off into a shorted load. Power off and measure output to ground.
  • Power off, input to output near 0 Ω: shorted.
On the board:
An output at 0 V is often a shorted load with the regulator in current limit. Lift the output pin: if the short stays on the board, the regulator may be fine.
Compare:
The same regulator on another rail or another board shows the right voltages and the right resistances.
Watch for:
Makers put input, output and ground on different pins in the same package, so take them from this part's datasheet. Diode or ohms readings between its pins say little; check it powered.

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 WMs

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 WMs

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

Did you find your part?

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