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SMD code KXs in SOT-343

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 KX was searched.

3 parts in SOT-343 are printed KXs

Not sure which one you have?

Answer up to 4 quick questions and these 33 parts are ranked, with a meter test that settles it. It works on a dead part too.

  • BF5030WSOT-343RF transistor, InfineonRF transistorInfineon
    What it is
    RF transistor
    Maker
    Infineon
    Package
    SOT-343
    Pins
    4
    Source
    Manufacturer datasheet

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

  • PT7M6228CHC4SOT-343Voltage supervisor, Pericom TechnologyVoltage supervisorPericom Technology
    What it is
    Voltage supervisor
    Maker
    Pericom Technology
    Package
    SOT-343
    Pins
    4
    Details
    Voltage detector IC: 2.8V±1.5%, +Reset PPO
    Source
    Published code list

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

  • PT7M6228CHC4ESOT-343Voltage supervisor, Pericom TechnologyVoltage supervisorPericom Technology
    What it is
    Voltage supervisor
    Maker
    Pericom Technology
    Package
    SOT-343
    Pins
    4
    Details
    Voltage detector IC: 2.8V±1.5%, +Reset PPO, Lead free
    Source
    Published code list

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

  • 12 more parts have no package on record. Nothing rules them out, so they stay.
    • FSA881UMLogic gate, onsemiLogic gateonsemi
      What it is
      Logic gate
      Maker
      onsemi
      Package
      Not recorded
      Pins
      Not recorded
      Details
      / - USB Port 2:1 Switch with Accessory and Charger Detection
      Source
      Manufacturer datasheet

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

    • SMF10A-MFHTVS diode, Formosa MicrosemiTVS diodeFormosa 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.

    • SMF10A-MFLTVS diode, Formosa MicrosemiTVS diodeFormosa 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.

    • SMF10A-MSTVS diode, Formosa MicrosemiTVS diodeFormosa 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.

    • SMF10A-MS-Q1TVS diode, Formosa MicrosemiTVS diodeFormosa 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.

    • VS90VLNVWMTVS 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.

    • VS90VLNVWMTFTVS 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.

    • 2SK3291Sanyo ElectricNot recordedSanyo Electric
      What it is
      Not recorded
      Maker
      Sanyo Electric
      Package
      Not recorded
      Pins
      Not recorded
      Details
      n-MOS*-e: Sw, U-Hi-Sp, 60V, 1,6A, 1.3W, 5/18ns, 0,68Ω(0.8A)
      Source
      Published code list

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

    • BU45L274GVoltage supervisor, ROHMVoltage supervisorROHM
      What it is
      Voltage supervisor
      Maker
      ROHM
      Package
      Not recorded
      Pins
      Not recorded
      Details
      Voltage detector IC: 2.7V±1%, -Reset ODO, Rdt=400ms
      Source
      Published code list

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

    • BU4938FVoltage supervisor, ROHMVoltage supervisorROHM
      What it is
      Voltage supervisor
      Maker
      ROHM
      Package
      Not recorded
      Pins
      Not recorded
      Details
      CMOS-IC: Voltage Detector 3,8V, Reset Push-pull output
      Source
      Published code list

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

    • BU4938FWEVoltage supervisor, ROHMVoltage supervisorROHM
      What it is
      Voltage supervisor
      Maker
      ROHM
      Package
      Not recorded
      Pins
      Not recorded
      Details
      CMOS-IC: Voltage Detector 3,8V, Reset Push-pull output
      Source
      Published code list

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

    • BU4938GVoltage supervisor, ROHMVoltage supervisorROHM
      What it is
      Voltage supervisor
      Maker
      ROHM
      Package
      Not recorded
      Pins
      Not recorded
      Details
      CMOS-IC: Voltage Detector 3,8V, Reset Push-pull output
      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.

Bipolar transistor

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

Working, it reads

From the base, one probe colour 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.

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.

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 KXs

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 KXs

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

Codes not listed here are printed on 56 more parts.

Did you find your part?

Open this in the search to correct a character or try another package.