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SMD code 5Fa

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, a, is lower case, which on NXP and Philips parts is a date or factory code, so it was set aside and 5F was searched.

106 parts are printed 5Fa

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.

  • WE40115FSOD-882ESD protection diode, 2 pins, WayonESD protection diodeSOD-8822 pinsWayon
    What it is
    ESD protection diode
    Maker
    Wayon
    Package
    SOD-882
    Pins
    2
    Source
    Manufacturer datasheet

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

  • ESD1006B5V0SOD-882ESD protection diode, 2 pins, YFWESD protection diodeSOD-8822 pinsYFW
    What it is
    ESD protection diode
    Maker
    YFW
    Package
    SOD-882
    Pins
    2
    Source
    Manufacturer datasheet

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

  • 2SK3539SOT-323N-channel MOSFET, 3 pins, PanasonicN-channel MOSFETSOT-3233 pinsPanasonic
    What it is
    N-channel MOSFET
    Maker
    Panasonic
    Package
    SOT-323
    Pins
    3
    Details
    MOSFET n-type: Sw, 50V, 100mA, 150mW, 8(10mA), 200/200ns
    Source
    Published code list

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

  • 2SK4072SOT-323N-channel MOSFET, 3 pins, PanasonicN-channel MOSFETSOT-3233 pinsPanasonic
    What it is
    N-channel MOSFET
    Maker
    Panasonic
    Package
    SOT-323
    Pins
    3
    Details
    MOSFET n-type: Sw, 25V, 100mA, 200mW, 6 (10mA), 200/200ns
    Source
    Published code list

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

  • APX803L05-37C3SOT-323Voltage supervisor, 3 pins, Diodes IncorporatedVoltage supervisorSOT-3233 pinsDiodes Incorporated
    What it is
    Voltage supervisor
    Maker
    Diodes Incorporated
    Package
    SOT-323
    Pins
    3
    Details
    Voltage detector IC: 3.7V±1.5%, -Reset ODO, Rdt=55ms
    Source
    Published code list

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

  • ATF-55143SOT-3234 pins, BroadcomNot recordedSOT-3234 pinsBroadcom
    What it is
    Not recorded
    Maker
    Broadcom
    Package
    SOT-323
    Pins
    4
    Details
    Low Noise Enhancement Mode Pseudomorphic HEMT
    Source
    Published code list

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

  • BC808-25WSOT-3233 pins, InfineonNot recordedSOT-3233 pinsInfineon
    What it is
    Not recorded
    Maker
    Infineon
    Package
    SOT-323
    Pins
    3
    Details
    Si-pnp: AF-Drv, 30V, 500mA, 330mW, B=160..400, >100MHz
    Source
    Published code list

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

  • BC808–25WT1SOT-3233 pins, onsemiNot recordedSOT-3233 pinsonsemi
    What it is
    Not recorded
    Maker
    onsemi
    Package
    SOT-323
    Pins
    3
    Source
    Published code list

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

  • BZX584C10SOD-523Zener diode, 2 pins, RectronZener diodeSOD-5232 pinsRectron
    What it is
    Zener diode
    Maker
    Rectron
    Package
    SOD-523
    Pins
    2
    Source
    Published code list

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

  • FSS115SMBSMBSchottky diode, 2 pins, Fagor ElectronicaSchottky diodeSMB2 pinsFagor Electronica
    What it is
    Schottky diode
    Maker
    Fagor Electronica
    Package
    SMB
    Pins
    2
    Details
    Diode: SBR, 150V, 1A, Vf<0.95V(1A)
    Source
    Published code list

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

  • 5 more parts have no package on record
    • 74AUP1T02GWNXPNot recordedNot recordedNot recordedNXP
      What it is
      Not recorded
      Maker
      NXP
      Package
      Not recorded
      Pins
      Not recorded
      Details
      CMOS logic IC: 2-input NOR gate with voltage-level translator
      Source
      Published code list

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

    • 74AUP1T02GXNXPNot recordedNot recordedNot recordedNXP
      What it is
      Not recorded
      Maker
      NXP
      Package
      Not recorded
      Pins
      Not recorded
      Details
      CMOS logic IC: 2-input NOR gate with voltage-level translator
      Source
      Published code list

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

    • AP7341D-22FS4-7RLDO regulator, Diodes IncorporatedLDO regulatorNot recordedNot recordedDiodes Incorporated
      What it is
      LDO regulator
      Maker
      Diodes Incorporated
      Package
      Not recorded
      Pins
      Not recorded
      Details
      Linear voltage regulator IC: LDO, 2.2V±1%, 300mA, +CE, CL
      Source
      Published code list

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

    • CDZ7.5BZener diode, ROHMZener diodeNot recordedNot recordedROHM
      What it is
      Zener diode
      Maker
      ROHM
      Package
      Not recorded
      Pins
      Not recorded
      Details
      Z-diode: 7,5V±2,5%, 40mA, 1W
      Source
      Published code list

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

    • CDZ55C5V6TZener diode, Crownpo TechnologyZener diodeNot recordedNot recordedCrownpo Technology
      What it is
      Zener diode
      Maker
      Crownpo Technology
      Package
      Not recorded
      Pins
      Not recorded
      Details
      Zener diode: 5.32..5.88V, Zzt=30, Izt=5mA, 200mW
      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.

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.

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.

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.

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.

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