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SMD code 8 in SOT-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.

3 parts in SOT-323 are printed 8

Not sure which one you have?

Answer up to 4 quick questions and these 18 parts are ranked, with a meter test that settles it. It works on a dead part too.

  • AX6903IASOT-323Voltage supervisor, 3 pins, AXElite TechnologyVoltage supervisor3 pinsAXElite Technology
    What it is
    Voltage supervisor
    Maker
    AXElite Technology
    Package
    SOT-323
    Pins
    3
    Details
    Voltage detector IC: 4.25V±1.5%, -Reset PPO
    Source
    Published code list

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

  • ELM7550CEBSOT-323Voltage supervisor, 3 pins, ELM TechnologyVoltage supervisor3 pinsELM Technology
    What it is
    Voltage supervisor
    Maker
    ELM Technology
    Package
    SOT-323
    Pins
    3
    Details
    Voltage detector IC: 5.0V±2%, +Reset PPO
    Source
    Published code list

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

  • ELM7550NEBSOT-323Voltage supervisor, 3 pins, ELM TechnologyVoltage supervisor3 pinsELM Technology
    What it is
    Voltage supervisor
    Maker
    ELM Technology
    Package
    SOT-323
    Pins
    3
    Details
    Voltage detector IC: 5.0V±2%, +Reset ODO
    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.
    • AOZ8S503BDS-05ESD protection diode, Alpha & Omega SemiconductorESD protection diodeNot recordedAlpha & Omega Semiconductor
      What it is
      ESD protection diode
      Maker
      Alpha & Omega Semiconductor
      Package
      Not recorded
      Pins
      Not recorded
      Source
      Manufacturer datasheet

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

    • AOZ8S513BDS-05ESD protection diode, Alpha & Omega SemiconductorESD protection diodeNot recordedAlpha & Omega Semiconductor
      What it is
      ESD protection diode
      Maker
      Alpha & Omega Semiconductor
      Package
      Not recorded
      Pins
      Not recorded
      Source
      Manufacturer datasheet

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

    • AOZ8839DI-05ESD protection diode, Alpha & Omega SemiconductorESD protection diodeNot recordedAlpha & Omega Semiconductor
      What it is
      ESD protection diode
      Maker
      Alpha & Omega Semiconductor
      Package
      Not recorded
      Pins
      Not recorded
      Details
      ESD protection for high-speed interfaces
      Source
      Manufacturer datasheet

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

    • FDZ192NZN-channel MOSFET, onsemiN-channel MOSFETNot recordedonsemi
      What it is
      N-channel MOSFET
      Maker
      onsemi
      Package
      Not recorded
      Pins
      Not recorded
      Details
      Power MOSFET, N-Channel, Trench , 1.5 V Specified Thin WLCSP
      Source
      Manufacturer datasheet

      Is it dead? The meter test is below: N-channel MOSFET.

    • MJD122RF transistor, Taitron ComponentsRF transistorNot recordedTaitron Components
      What it is
      RF transistor
      Maker
      Taitron Components
      Package
      Not recorded
      Pins
      Not recorded
      Details
      SMD RF/VHF/UHF Transistors
      Source
      Manufacturer datasheet

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

    • MJD127RF transistor, Taitron ComponentsRF transistorNot recordedTaitron Components
      What it is
      RF transistor
      Maker
      Taitron Components
      Package
      Not recorded
      Pins
      Not recorded
      Details
      SMD RF/VHF/UHF Transistors
      Source
      Manufacturer datasheet

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

    • PMEG3005AESFSchottky diode, 2 pins, NexperiaSchottky diode2 pinsNexperia
      What it is
      Schottky diode
      Maker
      Nexperia
      Package
      Not recorded
      Pins
      2
      Details
      30 V, 0.5 A low VF MEGA Schottky barrier rectifier
      Source
      Manufacturer datasheet

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

    • PS03TBUL2ESD protection diode, KECESD protection diodeNot recordedKEC
      What it is
      ESD protection diode
      Maker
      KEC
      Package
      Not recorded
      Pins
      Not recorded
      Source
      Manufacturer datasheet

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

    • TCR4DG45LDO regulator, ToshibaLDO regulatorNot recordedToshiba
      What it is
      LDO regulator
      Maker
      Toshiba
      Package
      Not recorded
      Pins
      Not recorded
      Details
      TCR4DG series
      Source
      Manufacturer datasheet

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

    • TCR5RG46ALDO regulator, ToshibaLDO regulatorNot recordedToshiba
      What it is
      LDO regulator
      Maker
      Toshiba
      Package
      Not recorded
      Pins
      Not recorded
      Details
      TCR5RG series
      Source
      Manufacturer datasheet

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

    • VS3V3BT1FSESD protection diode, ROHMESD protection diodeNot recordedROHM
      What it is
      ESD protection 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.

    • BBY58-02W2 pins, InfineonNot recorded2 pinsInfineon
      What it is
      Not recorded
      Maker
      Infineon
      Package
      Not recorded
      Pins
      2
      Details
      C-diode: Dual, Tuning, VCO, 10V, 5,5..6,6/17,5..19,3pF(4/1V)
      Source
      Published code list

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

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.

N-channel MOSFET

Diode range, part lifted. Test drain to source first, then short gate to source and test again.

Working, it reads

Red probe on the source, black on the drain: about 0.4 to 0.9 V, the body diode. Open the other way. The gate reads open to both other pins, both ways.

Dead, it reads

  • Drain to source the same both ways, near 0 V with a continuous beep, and still so after shorting gate to source: shorted. The classic failure.
  • The gate reads low to source or drain: gate shorted. Often all three pins end up shorted together.
  • No body diode at all: failed open.
On the board
the gate usually has a resistor to the source, so gate to source reads that resistor, which is not a fault. A drain short can be the load. Lift a leg to be sure.
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 diode range can charge the gate enough to turn the part on, and then drain to source reads near 0 both ways on a good part. Short gate to source and test again before you condemn it.

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.

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.

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.

Silicon diode

Diode range, part lifted or one leg off the pad. Red probe on the anode.

Working, it reads

About 0.5 to 0.8 V anode to cathode, and open the other way. Small switching diodes read about 0.6 to 0.7 V; large rectifiers can read a little lower.

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: failed open.
  • A reading the wrong way round as well: 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 three-pin body can hold two diodes. With a common pin they read two junctions from that pin, just like a transistor; in series they read two drops end to end. Test each pair the datasheet names.

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 8

One character differs, and it is one that is easy to confuse under a lamp. Each code has a page of its own.

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