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SMD code KW in SOD-128

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.

1 part in SOD-128 is printed KW

Not sure which one you have?

Answer up to 4 quick questions and these 10 parts are ranked, with a meter test that settles it. It works on a dead part too.

  • TPSMZ15ATGSOD-128TVS diode, Fagor ElectronicaTVS diodeFagor Electronica
    What it is
    TVS diode
    Maker
    Fagor Electronica
    Package
    SOD-128
    Pins
    2
    Details
    Transient voltage supressor: Vrm=12.8V, Vbr=14.3..15.8V, Ipp=28A, 600W
    Source
    Published code list

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

  • 9 more parts have no package on record. Nothing rules them out, so they stay.
    • VS12VUA1VWMTVS diode, ROHMTVS diodeROHM
      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.

      Datasheetfor VS12VUA1VWM, opens in a new tab
    • VS12VUA1VWMTFTVS diode, ROHMTVS diodeROHM
      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.

      Datasheetfor VS12VUA1VWMTF, opens in a new tab
    • BU45L264GVoltage supervisor, ROHMVoltage supervisorROHM
      What it is
      Voltage supervisor
      Maker
      ROHM
      Package
      Not recorded
      Pins
      Not recorded
      Details
      Voltage detector IC: 2.6V±1%, -Reset ODO, Rdt=400ms
      Source
      Published code list

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

    • BU4937FVoltage supervisor, ROHMVoltage supervisorROHM
      What it is
      Voltage supervisor
      Maker
      ROHM
      Package
      Not recorded
      Pins
      Not recorded
      Details
      CMOS-IC: Voltage Detector 3,7V, Reset Push-pull output
      Source
      Published code list

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

    • BU4937FWEVoltage supervisor, ROHMVoltage supervisorROHM
      What it is
      Voltage supervisor
      Maker
      ROHM
      Package
      Not recorded
      Pins
      Not recorded
      Details
      CMOS-IC: Voltage Detector 3,7V, Reset Push-pull output
      Source
      Published code list

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

    • BU4937GVoltage supervisor, ROHMVoltage supervisorROHM
      What it is
      Voltage supervisor
      Maker
      ROHM
      Package
      Not recorded
      Pins
      Not recorded
      Details
      CMOS-IC: Voltage Detector 3,7V, Reset Push-pull output
      Source
      Published code list

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

    • FP6812-23CC8PVoltage supervisor, FitipowerVoltage supervisorFitipower
      What it is
      Voltage supervisor
      Maker
      Fitipower
      Package
      Not recorded
      Pins
      Not recorded
      Details
      Voltage detector IC: 2.32V±1.5%, +Reset PPO, -MR
      Source
      Published code list

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

    • MDZ5241CZener diode, FutureWafer TechZener diodeFutureWafer Tech
      What it is
      Zener diode
      Maker
      FutureWafer Tech
      Package
      Not recorded
      Pins
      Not recorded
      Details
      Zener diode: 10.45..11.55V, Zzt=22.0, Izt=5.0mA, 150mW
      Source
      Published code list

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

    • R5426D112FDNisshinbo Micro DevicesNot recordedNisshinbo Micro Devices
      What it is
      Not recorded
      Maker
      Nisshinbo Micro Devices
      Package
      Not recorded
      Pins
      Not recorded
      Details
      CMOS-IC: Li-Ion Battery Over-charge/discharge Protection, Vc/d=1,12V
      Source
      Published code list

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

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.

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.

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.

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