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SMD code A21

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.

45 parts are printed A21

Not sure which one you have?

Answer up to 4 quick questions and these 45 parts are ranked, with a meter test that settles it. It works on a dead part too.

  • 2SK436-A21SOT-233 pins, onsemiNot recordedSOT-233 pinsonsemi
    What it is
    Not recorded
    Maker
    onsemi
    Package
    SOT-23
    Pins
    3
    Details
    n-FET: RF-AM, LN, 15V, 20mA, 150mW, Idss=5..8.5mA
    Source
    Published code list

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

  • AAT60221A-S5SOT-23-5Voltage supervisor, 5 pins, Advanced Analog TechnologyVoltage supervisorSOT-23-55 pinsAdvanced Analog Technology
    What it is
    Voltage supervisor
    Maker
    Advanced Analog Technology
    Package
    SOT-23-5
    Pins
    5
    Details
    Voltage detector IC: 2.1V±2%, -Reset PPO
    Source
    Published code list

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

  • AAT60221A-S15SOT-343Voltage supervisor, 4 pins, Advanced Analog TechnologyVoltage supervisorSOT-3434 pinsAdvanced Analog Technology
    What it is
    Voltage supervisor
    Maker
    Advanced Analog Technology
    Package
    SOT-343
    Pins
    4
    Details
    Voltage detector IC: 2.1V±2%, -Reset PPO
    Source
    Published code list

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

  • ADA4505-2ACBZ-RLWLCSP8 pins, Analog DevicesNot recordedWLCSP8 pinsAnalog Devices
    What it is
    Not recorded
    Maker
    Analog Devices
    Package
    WLCSP
    Pins
    8
    Source
    Published code list

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

  • ADA4505-2ARMZMSOP-88 pins, Analog DevicesNot recordedMSOP-88 pinsAnalog Devices
    What it is
    Not recorded
    Maker
    Analog Devices
    Package
    MSOP-8
    Pins
    8
    Source
    Published code list

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

  • CLC452AJM5SOT-23-55 pins, National SemiconductorNot recordedSOT-23-55 pinsNational Semiconductor
    What it is
    Not recorded
    Maker
    National Semiconductor
    Package
    SOT-23-5
    Pins
    5
    Details
    Op-IC: Lo-power, Current Feedback
    Source
    Published code list

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

  • ELM9721NABSOT-89Voltage supervisor, 3 pins, ELM TechnologyVoltage supervisorSOT-893 pinsELM Technology
    What it is
    Voltage supervisor
    Maker
    ELM Technology
    Package
    SOT-89
    Pins
    3
    Details
    Voltage detector IC: 2.1V±2.5%, +Reset ODO
    Source
    Published code list

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

  • ELM9721NBBSOT-23Voltage supervisor, 3 pins, ELM TechnologyVoltage supervisorSOT-233 pinsELM Technology
    What it is
    Voltage supervisor
    Maker
    ELM Technology
    Package
    SOT-23
    Pins
    3
    Details
    Voltage detector IC: 2.1V±2.5%, +Reset ODO
    Source
    Published code list

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

  • GS809C21EUASOT-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 2,1V, -Reset Push-pull output, 1,5ms
    Source
    Published code list

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

  • KIC77A21TSOT-23Voltage supervisor, 3 pins, KECVoltage supervisorSOT-233 pinsKEC
    What it is
    Voltage supervisor
    Maker
    KEC
    Package
    SOT-23
    Pins
    3
    Details
    Voltage detector IC: 2.1V±1%, -Reset ODO, Rdt=240ms
    Source
    Published code list

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

  • 5 more parts have no package on record
    • 2SK436JFET, SanyoJFETNot recordedNot recordedSanyo
      What it is
      JFET
      Maker
      Sanyo
      Package
      Not recorded
      Pins
      Not recorded
      Details
      N-channel JFET
      Source
      Published code list

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

    • 2SK436-21Sanyo ElectricNot recordedNot recordedNot recordedSanyo Electric
      What it is
      Not recorded
      Maker
      Sanyo Electric
      Package
      Not recorded
      Pins
      Not recorded
      Details
      FET n-type: RF-AM, LN, 15V, 20mA, 150mW, Idss=5..8.5mA
      Source
      Published code list

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

    • 2SK1066-21Sanyo ElectricNot recordedNot recordedNot recordedSanyo Electric
      What it is
      Not recorded
      Maker
      Sanyo Electric
      Package
      Not recorded
      Pins
      Not recorded
      Details
      n-FET: GP, 15V, 20mA, 100mW, Idss=5..8,5mA, Up<1,5V
      Source
      Published code list

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

    • APA2010AHAAnpec ElectronicsNot recordedNot recordedNot recordedAnpec Electronics
      What it is
      Not recorded
      Maker
      Anpec Electronics
      Package
      Not recorded
      Pins
      Not recorded
      Details
      Linear IC: APA, BTL, class-D, 2.7..5.5V, 3W(5V/4), shutdown
      Source
      Published code list

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

    • KIC77A21MVoltage supervisor, KECVoltage supervisorNot recordedNot recordedKEC
      What it is
      Voltage supervisor
      Maker
      KEC
      Package
      Not recorded
      Pins
      Not recorded
      Details
      Voltage detector IC: 2.1V±1%, -Reset ODO, Rdt=240ms
      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.

JFET

Ohms range for drain to source, diode range for the gate, part lifted.

Working, it reads

Drain to source conducts both ways at a few hundred ohms, depending on the part, and some meters beep on it. The gate reads one junction to drain and to source, about 0.6 to 0.7 V, and open the other way.

Dead, it reads

  • The gate the same both ways to drain or source, near 0 V with a continuous beep: gate shorted.
  • Drain to source open: the channel has 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:
Drain to source resistance varies from part to part. An identical part elsewhere on the board shows what is normal.
Watch for:
A good channel can beep like a short between drain and source. That is normal; the gate junction says whether it has failed.

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.

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.

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.

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