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SMD code MB in SOD-323

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

  • UFZV15BSOD-323Zener diode, ROHMZener diodeROHM
    What it is
    Zener diode
    Maker
    ROHM
    Package
    SOD-323
    Pins
    2
    Source
    Manufacturer datasheet

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

  • UFZVFH15BSOD-323Zener diode, ROHMZener diodeROHM
    What it is
    Zener diode
    Maker
    ROHM
    Package
    SOD-323
    Pins
    2
    Details
    Zener Diode (AEC-Q101 qualified)
    Source
    Manufacturer datasheet

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

  • 13 more parts have no package on record. Nothing rules them out, so they stay.
    • 2SAR512RPNP transistor, ROHMPNP transistorROHM
      What it is
      PNP transistor
      Maker
      ROHM
      Package
      Not recorded
      Pins
      Not recorded
      Details
      PNP -2.0A -30V Middle Power Transistor
      Source
      Manufacturer datasheet

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

    • BGB420RF amplifier (MMIC), InfineonRF amplifier (MMIC)Infineon
      What it is
      RF amplifier (MMIC)
      Maker
      Infineon
      Package
      Not recorded
      Pins
      Not recorded
      Source
      Manufacturer datasheet

      Is it dead? The meter test is below: RF amplifier.

    • KTC812TNPN transistor, KECNPN transistorKEC
      What it is
      NPN transistor
      Maker
      KEC
      Package
      Not recorded
      Pins
      Not recorded
      Source
      Manufacturer datasheet

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

    • PBZ5.6BZener diode, ROHMZener diodeROHM
      What it is
      Zener diode
      Maker
      ROHM
      Package
      Not recorded
      Pins
      Not recorded
      Source
      Manufacturer datasheet

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

    • RB168VWM200Schottky 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.

    • RB168VWM200TFSchottky diode, ROHMSchottky diodeROHM
      What it is
      Schottky diode
      Maker
      ROHM
      Package
      Not recorded
      Pins
      Not recorded
      Details
      Schottky Barrier Diode (AEC-Q101 qualified)
      Source
      Manufacturer datasheet

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

    • 74LVC1G02FX4Diodes IncorporatedNot recordedDiodes Incorporated
      What it is
      Not recorded
      Maker
      Diodes Incorporated
      Package
      Not recorded
      Pins
      Not recorded
      Details
      CMOS logic IC: 2-input NOR gate
      Source
      Published code list

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

    • BD49L36GVoltage supervisor, ROHMVoltage supervisorROHM
      What it is
      Voltage supervisor
      Maker
      ROHM
      Package
      Not recorded
      Pins
      Not recorded
      Details
      Voltage Detector
      Source
      Published code list

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

    • BD52E26G-MVoltage 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
      Source
      Published code list

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

    • BU45L304GVoltage supervisor, ROHMVoltage supervisorROHM
      What it is
      Voltage supervisor
      Maker
      ROHM
      Package
      Not recorded
      Pins
      Not recorded
      Details
      Voltage detector IC: 3.0V±1%, -Reset ODO, Rdt=400ms
      Source
      Published code list

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

    • IXD5120N412NR-GVoltage supervisor, IXYSVoltage supervisorIXYS
      What it is
      Voltage supervisor
      Maker
      IXYS
      Package
      Not recorded
      Pins
      Not recorded
      Details
      Voltage detector IC: 4.1V±2% -Reset ODO
      Source
      Published code list

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

    • IXD5127N18KNRVoltage supervisor, IXYSVoltage supervisorIXYS
      What it is
      Voltage supervisor
      Maker
      IXYS
      Package
      Not recorded
      Pins
      Not recorded
      Details
      Voltage detector IC: 1.8V±0.8%, +Reset ODO, -MR, 800ms Rt delay
      Source
      Published code list

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

    • KDZ5.6BZener diode, ROHMZener diodeROHM
      What it is
      Zener diode
      Maker
      ROHM
      Package
      Not recorded
      Pins
      Not recorded
      Details
      Z-diode: 5,6V±2,5%, 40mA, 1W
      Source
      Published code list

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

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.

RF amplifier

Voltage, board powered, on the output pin that the bias resistor or choke feeds.

Working, it reads

The output pin sits at the device voltage the datasheet gives, a few volts, below the supply.

Dead, it reads

  • Output pin at 0 V, or near 0 Ω to ground with the power off: shorted inside.
  • Output pin at the full supply voltage: open inside, no current flowing.
On the board:
Measured on the board with power on; the bias network is part of the reading.
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 figures depend on the part and its bias resistor. 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.

NPN transistor

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

Working, it reads

Red 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.

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.

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 MB

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 MB

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 143 more parts.

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