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SMD code K3 in SOT-23-5

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

  • EM5213AJ-30SOT-23-5Load switch, Excelliance MOSLoad switchExcelliance MOS
    What it is
    Load switch
    Maker
    Excelliance MOS
    Package
    SOT-23-5
    Pins
    5
    Details
    Power switch
    Source
    Manufacturer datasheet

    Is it dead? The meter test is below: Load switch.

  • BCT2020EUK33-TRSOT-23-5LDO regulator, Broadchip Technology GroupLDO regulatorBroadchip Technology Group
    What it is
    LDO regulator
    Maker
    Broadchip Technology Group
    Package
    SOT-23-5
    Pins
    5
    Details
    Linear voltage regulator IC: LDO, 3.3V±2%, 200mA, +CE
    Source
    Published code list

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

  • BCT2036EUK33-TRSOT-23-5LDO regulator, Broadchip Technology GroupLDO regulatorBroadchip Technology Group
    What it is
    LDO regulator
    Maker
    Broadchip Technology Group
    Package
    SOT-23-5
    Pins
    5
    Details
    Linear voltage regulator IC: LDO, 3.3V±2.5%, 300mA, +CE
    Source
    Published code list

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

  • ELM89333BSOT-23-5LDO regulator, ELM TechnologyLDO regulatorELM Technology
    What it is
    LDO regulator
    Maker
    ELM Technology
    Package
    SOT-23-5
    Pins
    5
    Details
    Linear voltage regulator IC: LDO, 3.3V±2%, 300mA, +CE
    Source
    Published code list

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

  • FP6146-28S8GSOT-23-5LDO regulator, FitipowerLDO regulatorFitipower
    What it is
    LDO regulator
    Maker
    Fitipower
    Package
    SOT-23-5
    Pins
    5
    Details
    Linear voltage regulator IC: LDO, 2.8V±2%, 300mA, +CE
    Source
    Published code list

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

  • RN5RG33AASOT-23-5Nisshinbo Micro DevicesNot recordedNisshinbo Micro Devices
    What it is
    Not recorded
    Maker
    Nisshinbo Micro Devices
    Package
    SOT-23-5
    Pins
    5
    Details
    VR-IC: Ext. transistor, 3.3V±2,5% 1A*
    Source
    Published code list

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

  • RN5RY231ASOT-23-5Nisshinbo Micro DevicesNot recordedNisshinbo Micro Devices
    What it is
    Not recorded
    Maker
    Nisshinbo Micro Devices
    Package
    SOT-23-5
    Pins
    5
    Details
    VR-IC: VFM step-up DC-DC conv. ctrl, 2,3V±2,5%, 150mW, <180KHz
    Source
    Published code list

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

  • RT9167A-18CBRSOT-23-5LDO regulator, RichtekLDO regulatorRichtek
    What it is
    LDO regulator
    Maker
    Richtek
    Package
    SOT-23-5
    Pins
    5
    Details
    VR-IC: LDO, CE, 1.8V±2%, 600mA
    Source
    Published code list

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

  • 7 more parts have no package on record. Nothing rules them out, so they stay.
    • HFCN-1810+RF filter, Mini-CircuitsRF filterMini-Circuits
      What it is
      RF filter
      Maker
      Mini-Circuits
      Package
      Not recorded
      Pins
      Not recorded
      Details
      LTCC filter, 1950-4750 MHz
      Source
      Manufacturer datasheet

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

    • HFCN-1810D+RF filter, Mini-CircuitsRF filterMini-Circuits
      What it is
      RF filter
      Maker
      Mini-Circuits
      Package
      Not recorded
      Pins
      Not recorded
      Details
      LTCC filter, 1950-4750 MHz
      Source
      Manufacturer datasheet

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

    • MMBZ5253BWSZener diode, Taitron ComponentsZener diodeTaitron Components
      What it is
      Zener diode
      Maker
      Taitron Components
      Package
      Not recorded
      Pins
      Not recorded
      Details
      SMD Zener Diodes (Three Terminals) - 200mW
      Source
      Manufacturer datasheet

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

    • NCV8135BMTW040LDO regulator, onsemiLDO regulatoronsemi
      What it is
      LDO regulator
      Maker
      onsemi
      Package
      Not recorded
      Pins
      Not recorded
      Details
      500 mA, Very Low Dropout Bias Rail CMOS Voltage Regulator
      Source
      Manufacturer datasheet

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

    • RB058LB100Schottky diode, ROHMSchottky diodeROHM
      What it is
      Schottky diode
      Maker
      ROHM
      Package
      Not recorded
      Pins
      Not recorded
      Details
      Schottky Barrier Diode
      Source
      Manufacturer datasheet

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

    • AP8821N-23GIVoltage supervisor, Anwell SemiconductorVoltage supervisorAnwell Semiconductor
      What it is
      Voltage supervisor
      Maker
      Anwell Semiconductor
      Package
      Not recorded
      Pins
      Not recorded
      Details
      Voltage detector IC: 2.3V±2%, -Reset ODO, H-free
      Source
      Published code list

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

    • AP8821N-23GSVoltage supervisor, Anwell SemiconductorVoltage supervisorAnwell Semiconductor
      What it is
      Voltage supervisor
      Maker
      Anwell Semiconductor
      Package
      Not recorded
      Pins
      Not recorded
      Details
      Voltage detector IC: 2.3V±2%, -Reset ODO, H-free
      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.

Load switch

Voltage, board powered, black probe on ground.

Working, it reads

Switched on, the output pin sits at the input voltage. Switched off, it sits near 0 V.

Dead, it reads

  • Output at the input voltage while switched off: the pass element has shorted.
  • Input present and switched on, no output: failed open, or shut down into a shorted load. Power off and measure output to ground.
On the board:
An output near 0 Ω to ground is usually the load. Lift the output pin to see which.
Compare:
If an identical part sits elsewhere on the board, measure it the same way: that is what this one should read.
Watch for:
The pinout and whether the enable is active high or low differ between parts. The datasheet gives both.

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.

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.

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.

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.

Codes that begin with K3

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 140 more parts.

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