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SMD code 3At

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, t, is lower case, which on NXP and Philips parts is a date or factory code, so it was set aside and 3A was searched.

130 parts are printed 3At

Not sure which one you have?

Answer up to 4 quick questions and these 50 parts are ranked, with a meter test that settles it. It works on a dead part too.

  • PSGP3ASOD-323Rectifier, 2 pins, PrisemiRectifierSOD-3232 pinsPrisemi
    What it is
    Rectifier
    Maker
    Prisemi
    Package
    SOD-323
    Pins
    2
    Details
    Rectifier diode, 1 A, 200 V
    Source
    Manufacturer datasheet

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

  • RB058MM200SOD-123FSchottky diode, 2 pins, ROHMSchottky diodeSOD-123F2 pinsROHM
    What it is
    Schottky diode
    Maker
    ROHM
    Package
    SOD-123F
    Pins
    2
    Details
    Schottky Barrier Diode
    Source
    Manufacturer datasheet

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

  • RB058MM200TFSOD-123FSchottky diode, 2 pins, ROHMSchottky diodeSOD-123F2 pinsROHM
    What it is
    Schottky diode
    Maker
    ROHM
    Package
    SOD-123F
    Pins
    2
    Details
    Schottky Barrier Diode (AEC-Q101 qualified)
    Source
    Manufacturer datasheet

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

  • S-LBC856ALT1GSOT-23PNP transistor, 3 pins, LRCPNP transistorSOT-233 pinsLRC
    What it is
    PNP transistor
    Maker
    LRC
    Package
    SOT-23
    Pins
    3
    Details
    Bipolar transistor, PNP, IC 100 mA, VCEO 65 V
    Source
    Manufacturer datasheet

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

  • S-LESD5Z3.3AT5GSOD-523ESD protection diode, 2 pins, LRCESD protection diodeSOD-5232 pinsLRC
    What it is
    ESD protection diode
    Maker
    LRC
    Package
    SOD-523
    Pins
    2
    Details
    ESD protection diode, VRWM 3.3 V, IR @VRWM 1 μA, VBR Min 5 V
    Source
    Manufacturer datasheet

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

  • S1DWS-HFSOD-323Rectifier, 2 pins, ComchipRectifierSOD-3232 pinsComchip
    What it is
    Rectifier
    Maker
    Comchip
    Package
    SOD-323
    Pins
    2
    Details
    200 V, 1 A rectifier
    Source
    Manufacturer datasheet

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

  • SBC856ALSOT-23PNP transistor, 3 pins, onsemiPNP transistorSOT-233 pinsonsemi
    What it is
    PNP transistor
    Maker
    onsemi
    Package
    SOT-23
    Pins
    3
    Details
    General Purpose Transistors Series
    Source
    Manufacturer datasheet

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

  • SBC856ALT1GSOT-23PNP transistor, 3 pins, HXYPNP transistorSOT-233 pinsHXY
    What it is
    PNP transistor
    Maker
    HXY
    Package
    SOT-23
    Pins
    3
    Details
    Bipolar transistor, 65 V, 0.1 A
    Source
    Manufacturer datasheet

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

  • SM4003WSSOD-323Rectifier, 2 pins, YFWRectifierSOD-3232 pinsYFW
    What it is
    Rectifier
    Maker
    YFW
    Package
    SOD-323
    Pins
    2
    Details
    Rectifier diode
    Source
    Manufacturer datasheet

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

  • SR3.3SOT-143ESD protection diode, 4 pins, ProTek DevicesESD protection diodeSOT-1434 pinsProTek Devices
    What it is
    ESD protection diode
    Maker
    ProTek Devices
    Package
    SOT-143
    Pins
    4
    Details
    ESD protection diode, VRWM 3.3 V, Cj 0.8 pF
    Source
    Manufacturer datasheet

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

  • TBC856ASOT-23PNP transistor, 3 pins, Galaxy MicroelectronicsPNP transistorSOT-233 pinsGalaxy Microelectronics
    What it is
    PNP transistor
    Maker
    Galaxy Microelectronics
    Package
    SOT-23
    Pins
    3
    Details
    65V, 0.1A, General Purpose PNP Bipolar Transistor
    Source
    Manufacturer datasheet

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

  • TMBRX3A0SOD-123FSchottky diode, 2 pins, Galaxy MicroelectronicsSchottky diodeSOD-123F2 pinsGalaxy Microelectronics
    What it is
    Schottky diode
    Maker
    Galaxy Microelectronics
    Package
    SOD-123F
    Pins
    2
    Details
    3A, 100V, Surface Mount Schottky Barrier Rectifiers
    Source
    Manufacturer datasheet

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

  • TMMSZ5263ASOD-123Zener diode, 2 pins, Galaxy MicroelectronicsZener diodeSOD-1232 pinsGalaxy Microelectronics
    What it is
    Zener diode
    Maker
    Galaxy Microelectronics
    Package
    SOD-123
    Pins
    2
    Details
    56V, 500mW, Surface Mount Zener Diodes
    Source
    Manufacturer datasheet

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

  • 2 more parts have no package on record
    • RB168L-40Schottky diode, ROHMSchottky diodeNot recordedNot recordedROHM
      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.

    • RB168L-40TFSchottky diode, ROHMSchottky diodeNot recordedNot recordedROHM
      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.

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.

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.

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.

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.

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.

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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