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SMD code 4Ap

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, p, is lower case, which on NXP and Philips parts is a date or factory code, so it was set aside and 4A was searched.

92 parts are printed 4Ap

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.

  • MM1Z2V0BWSOD-123Zener diode, 2 pins, JSMSEMIZener diodeSOD-1232 pinsJSMSEMI
    What it is
    Zener diode
    Maker
    JSMSEMI
    Package
    SOD-123
    Pins
    2
    Source
    Manufacturer datasheet

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

  • MM1Z2V0WSOD-123Zener diode, 2 pins, HXYZener diodeSOD-1232 pinsHXY
    What it is
    Zener diode
    Maker
    HXY
    Package
    SOD-123
    Pins
    2
    Details
    Zener diode, 22 V, 0.005 A
    Source
    Manufacturer datasheet

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

  • MM5Z4678SOD-523Zener diode, 2 pins, onsemiZener diodeSOD-5232 pinsonsemi
    What it is
    Zener diode
    Maker
    onsemi
    Package
    SOD-523
    Pins
    2
    Details
    Zener Voltage Regulators MM5Z4xxxTxG Series, SZMM5Z4xxxTxG Series
    Source
    Manufacturer datasheet

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

  • PJSOT12SOT-23ESD protection diode, 3 pins, PanjitESD protection diodeSOT-233 pinsPanjit
    What it is
    ESD protection diode
    Maker
    Panjit
    Package
    SOT-23
    Pins
    3
    Details
    12V, 500W, Surface Mount TVS
    Source
    Manufacturer datasheet

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

  • PSBD5D40V1HXSOD-523Schottky diode, 2 pins, PrisemiSchottky diodeSOD-5232 pinsPrisemi
    What it is
    Schottky diode
    Maker
    Prisemi
    Package
    SOD-523
    Pins
    2
    Details
    Schottky diode, 40 V, 1 A
    Source
    Manufacturer datasheet

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

  • PSGP4ASOD-323Rectifier, 2 pins, PrisemiRectifierSOD-3232 pinsPrisemi
    What it is
    Rectifier
    Maker
    Prisemi
    Package
    SOD-323
    Pins
    2
    Details
    Rectifier diode, 1 A, 400 V
    Source
    Manufacturer datasheet

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

  • S1GWS-HFSOD-323Rectifier, 2 pins, ComchipRectifierSOD-3232 pinsComchip
    What it is
    Rectifier
    Maker
    Comchip
    Package
    SOD-323
    Pins
    2
    Details
    400 V, 1 A rectifier
    Source
    Manufacturer datasheet

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

  • SM4004WSSOD-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.

  • TL431ACPKSOT-89Voltage reference, 3 pins, Texas InstrumentsVoltage referenceSOT-893 pinsTexas Instruments
    What it is
    Voltage reference
    Maker
    Texas Instruments
    Package
    SOT-89
    Pins
    3
    Details
    Precision Programmable Reference
    Source
    Manufacturer datasheet

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

  • WSR4010BFSOD-882Schottky diode, 2 pins, WayonSchottky diodeSOD-8822 pinsWayon
    What it is
    Schottky diode
    Maker
    Wayon
    Package
    SOD-882
    Pins
    2
    Source
    Manufacturer datasheet

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

  • WSR4010D5SOD-523Schottky diode, 2 pins, WayonSchottky diodeSOD-5232 pinsWayon
    What it is
    Schottky diode
    Maker
    Wayon
    Package
    SOD-523
    Pins
    2
    Source
    Manufacturer datasheet

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

  • 4 more parts have no package on record
    • RB168L-60Schottky 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-60TFSchottky 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.

    • TVT12WESD protection diode, Taitron ComponentsESD protection diodeNot recordedNot recordedTaitron Components
      What it is
      ESD protection diode
      Maker
      Taitron Components
      Package
      Not recorded
      Pins
      Not recorded
      Details
      SMD TVS Arrays (Three Terminals)
      Source
      Manufacturer datasheet

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

    • 74LVC2T45RA3Diodes IncorporatedNot recordedNot recordedNot recordedDiodes Incorporated
      What it is
      Not recorded
      Maker
      Diodes Incorporated
      Package
      Not recorded
      Pins
      Not recorded
      Details
      CMOS logic IC: Dual-bit, dual-supply voltage level translator/transceiver; 3-state
      Source
      Published code list

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

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.

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.

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.

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.

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.

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