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SMD code 3400 in SOT-23

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.

12 parts in SOT-23 are printed 3400

Not sure which one you have?

Answer up to 4 quick questions and these 13 parts are ranked, with a meter test that settles it. It works on a dead part too.

  • BL3400SOT-23N-channel MOSFET, Galaxy MicroelectronicsN-channel MOSFETGalaxy Microelectronics
    What it is
    N-channel MOSFET
    Maker
    Galaxy Microelectronics
    Package
    SOT-23
    Pins
    3
    Details
    5.7A, 30V, 1.4W, N Channel, Power MOSFETs
    Source
    Manufacturer datasheet

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

    Datasheetfor BL3400, opens in a new tab
  • BL3400-3LSOT-23N-channel MOSFET, Galaxy MicroelectronicsN-channel MOSFETGalaxy Microelectronics
    What it is
    N-channel MOSFET
    Maker
    Galaxy Microelectronics
    Package
    SOT-23
    Pins
    3
    Details
    5.7A, 30V, 1.4W, N Channel, Power MOSFETs
    Source
    Manufacturer datasheet

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

    Datasheetfor BL3400-3L, opens in a new tab
  • EM03N58MSOT-23N-channel MOSFET, ETEKN-channel MOSFETETEK
    What it is
    N-channel MOSFET
    Maker
    ETEK
    Package
    SOT-23
    Pins
    3
    Source
    Manufacturer datasheet

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

    Datasheetfor EM03N58M, opens in a new tab
  • FMOS3400ASOT-23MOSFET, Formosa MicrosemiMOSFETFormosa Microsemi
    What it is
    MOSFET
    Maker
    Formosa Microsemi
    Package
    SOT-23
    Pins
    3
    Source
    Manufacturer datasheet

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

    Datasheetfor FMOS3400A, opens in a new tab
  • FMOS3400A-Q1SOT-23MOSFET, Formosa MicrosemiMOSFETFormosa Microsemi
    What it is
    MOSFET
    Maker
    Formosa Microsemi
    Package
    SOT-23
    Pins
    3
    Source
    Manufacturer datasheet

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

    Datasheetfor FMOS3400A-Q1, opens in a new tab
  • JMTJ3400ASOT-23Load switch, JieJieLoad switchJieJie
    What it is
    Load switch
    Maker
    JieJie
    Package
    SOT-23
    Pins
    3
    Source
    Manufacturer datasheet

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

    Datasheetfor JMTJ3400A, opens in a new tab
  • JMTL3400ASOT-23Load switch, JieJieLoad switchJieJie
    What it is
    Load switch
    Maker
    JieJie
    Package
    SOT-23
    Pins
    3
    Source
    Manufacturer datasheet

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

    Datasheetfor JMTL3400A, opens in a new tab
  • L3400ASOT-23N-channel MOSFET, Yangjie Electronic TechN-channel MOSFETYangjie Electronic Tech
    What it is
    N-channel MOSFET
    Maker
    Yangjie Electronic Tech
    Package
    SOT-23
    Pins
    3
    Source
    Manufacturer datasheet

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

    Datasheetfor L3400A, opens in a new tab
  • SMG3400SOT-23MOSFET, SeCoSMOSFETSeCoS
    What it is
    MOSFET
    Maker
    SeCoS
    Package
    SOT-23
    Pins
    3
    Source
    Manufacturer datasheet

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

    Datasheetfor SMG3400, opens in a new tab
  • SMS3400Y-CSOT-23MOSFET, SeCoSMOSFETSeCoS
    What it is
    MOSFET
    Maker
    SeCoS
    Package
    SOT-23
    Pins
    3
    Source
    Manufacturer datasheet

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

    Datasheetfor SMS3400Y-C, opens in a new tab
  • TBL3400SOT-23N-channel MOSFET, Galaxy MicroelectronicsN-channel MOSFETGalaxy Microelectronics
    What it is
    N-channel MOSFET
    Maker
    Galaxy Microelectronics
    Package
    SOT-23
    Pins
    3
    Details
    5.7A, 30V, 1.4W, N Channel, Power MOSFETs
    Source
    Manufacturer datasheet

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

    Datasheetfor TBL3400, opens in a new tab
  • MTN3400N3SOT-23N-channel MOSFETN-channel MOSFETNot recorded
    What it is
    N-channel MOSFET
    Maker
    Not recorded
    Package
    SOT-23
    Pins
    3
    Source
    Published code list

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

  • 1 more part has no package on record. Nothing rules it out, so it stays.

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.

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.

MOSFET

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

Working, it reads

One way between drain and source reads about 0.4 to 0.9 V, the body diode, and the other way open. The gate reads open to both other pins.

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.
  • No body diode at all: failed open.
On the board
the gate usually has a resistor to the source, which reads as that resistor and is not a fault. 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.

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.

Codes that begin with 3400

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

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