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SMD code AHs

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

181 parts are printed AHs

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.

  • BCP53T1SOT-223PNP transistor, 4 pins, onsemiPNP transistorSOT-2234 pinsonsemi
    What it is
    PNP transistor
    Maker
    onsemi
    Package
    SOT-223
    Pins
    4
    Details
    PNP transistor: AF, 100V, 1A, 1.3W, B=40..250, 115MHz
    Source
    Published code list

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

  • BCW70HSOT-23PNP transistor, 3 pins, InfineonPNP transistorSOT-233 pinsInfineon
    What it is
    PNP transistor
    Maker
    Infineon
    Package
    SOT-23
    Pins
    3
    Details
    PNP transistor: GP, 45V, 100mA, 200mW, B=180..310, >150MHz
    Source
    Published code list

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

  • BZX884-B11SOD-8822 pins, NXPNot recordedSOD-8822 pinsNXP
    What it is
    Not recorded
    Maker
    NXP
    Package
    SOD-882
    Pins
    2
    Details
    Z-diode: 11V±2%, 250mW
    Source
    Published code list

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

  • CP2297LDDFNChiphomer TechnologyNot recordedDFNNot recordedChiphomer Technology
    What it is
    Not recorded
    Maker
    Chiphomer Technology
    Package
    DFN
    Pins
    Not recorded
    Details
    Linear IC: APA, BTL, 2.5..5.5V, 3.1W(5V/8), shutdown
    Source
    Published code list

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

  • EC76SMAJ6.5SMATVS diode, 2 pins, E-CMOSTVS diodeSMA2 pinsE-CMOS
    What it is
    TVS diode
    Maker
    E-CMOS
    Package
    SMA
    Pins
    2
    Details
    Transient voltage supressor: Vbr=7.22..8.82V, Vrwm=6.5V, Ipp=32.5A, 400W(1ms)
    Source
    Published code list

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

  • EC76SMBJ6.5CSMBTVS diode, 2 pins, E-CMOSTVS diodeSMB2 pinsE-CMOS
    What it is
    TVS diode
    Maker
    E-CMOS
    Package
    SMB
    Pins
    2
    Details
    Transient voltage supressor: Vbr=7.22..8.82V, Vrwm=6.5V, Ipp=48.8A, 600W(1ms), Bidir.
    Source
    Published code list

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

  • ELM99271BSOT-89LDO regulator, 3 pins, ELM TechnologyLDO regulatorSOT-893 pinsELM Technology
    What it is
    LDO regulator
    Maker
    ELM Technology
    Package
    SOT-89
    Pins
    3
    Details
    Linear voltage regulator IC: LDO, 2.7V±2%, 300mA
    Source
    Published code list

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

  • GS6333UR16D1SOT-23Voltage supervisor, 3 pins, VishayVoltage supervisorSOT-233 pinsVishay
    What it is
    Voltage supervisor
    Maker
    Vishay
    Package
    SOT-23
    Pins
    3
    Details
    CMOS-IC: Voltage Detector 1,6V, -Reset Push-pull output, 1,5ms
    Source
    Published code list

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

  • 7 more parts have no package on record
    • BCP53MPNP transistor, 5 pins, InfineonPNP transistorNot recorded5 pinsInfineon
      What it is
      PNP transistor
      Maker
      Infineon
      Package
      Not recorded
      Pins
      5
      Details
      PNP transistor: AF-Dr/Out, 100V, 1A, 1.7W, B=40..250, 100MHz
      Source
      Published code list

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

    • BD7LS32G-CROHMNot recordedNot recordedNot recordedROHM
      What it is
      Not recorded
      Maker
      ROHM
      Package
      Not recorded
      Pins
      Not recorded
      Details
      CMOS logic IC: 2-input OR gate
      Source
      Published code list

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

    • BD48E30GVoltage supervisor, ROHMVoltage supervisorNot recordedNot recordedROHM
      What it is
      Voltage supervisor
      Maker
      ROHM
      Package
      Not recorded
      Pins
      Not recorded
      Details
      Voltage detector
      Source
      Published code list

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

    • BD48K30GVoltage supervisor, ROHMVoltage supervisorNot recordedNot recordedROHM
      What it is
      Voltage supervisor
      Maker
      ROHM
      Package
      Not recorded
      Pins
      Not recorded
      Details
      Voltage detector
      Source
      Published code list

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

    • BU29TA2WNVXLDO regulator, ROHMLDO regulatorNot recordedNot recordedROHM
      What it is
      LDO regulator
      Maker
      ROHM
      Package
      Not recorded
      Pins
      Not recorded
      Details
      Linear voltage regulator IC: LDO, 2.9V±1%, 200mA, +CE
      Source
      Published code list

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

    • BU45K302GVoltage supervisor, ROHMVoltage supervisorNot recordedNot recordedROHM
      What it is
      Voltage supervisor
      Maker
      ROHM
      Package
      Not recorded
      Pins
      Not recorded
      Details
      Voltage detector IC: 3.0V±1%, -Reset ODO, Rdt=200ms
      Source
      Published code list

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

    • HD74ALVC1G240VSRenesasNot recordedNot recordedNot recordedRenesas
      What it is
      Not recorded
      Maker
      Renesas
      Package
      Not recorded
      Pins
      Not recorded
      Details
      CMOS logic IC: Bus buffer inverted with 3-state output
      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.

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.

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.

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.

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.

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