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SMD code KY in DFN0603-2

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.

Not sure which one you have?

Answer up to 4 quick questions and these 27 parts are ranked, with a meter test that settles it. It works on a dead part too.

  • ZMMC4V1DFN0603-2Zener diode, RectronZener diodeRectron
    What it is
    Zener diode
    Maker
    Rectron
    Package
    DFN0603-2
    Pins
    2
    Source
    Manufacturer datasheet

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

  • 14 more parts have no package on record. Nothing rules them out, so they stay.
    • BG5130RRF amplifier (MMIC), InfineonRF amplifier (MMIC)Infineon
      What it is
      RF amplifier (MMIC)
      Maker
      Infineon
      Package
      Not recorded
      Pins
      Not recorded
      Source
      Manufacturer datasheet

      Is it dead? The meter test is below: RF amplifier.

    • FAN48615UC08XDC-DC converter, onsemiDC-DC converteronsemi
      What it is
      DC-DC converter
      Maker
      onsemi
      Package
      Not recorded
      Pins
      Not recorded
      Details
      Fixed-Output Synchronous TinyBoost Regulator
      Source
      Manufacturer datasheet

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

    • 2SK3292Sanyo ElectricNot recordedSanyo Electric
      What it is
      Not recorded
      Maker
      Sanyo Electric
      Package
      Not recorded
      Pins
      Not recorded
      Details
      n-MOS*-e: Sw, U-Hi-Sp, 60V, 2A, 1.5W, 7/24ns, 0,44Ω(1A)
      Source
      Published code list

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

    • BD49L34GVoltage supervisor, ROHMVoltage supervisorROHM
      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.

    • BF5040WInfineonNot recordedInfineon
      What it is
      Not recorded
      Maker
      Infineon
      Package
      Not recorded
      Pins
      Not recorded
      Details
      1GHz dg RF semi bias mosfet 3-5V 25mA gfs 41mS
      Source
      Published code list

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

    • BU45L284GVoltage supervisor, ROHMVoltage supervisorROHM
      What it is
      Voltage supervisor
      Maker
      ROHM
      Package
      Not recorded
      Pins
      Not recorded
      Details
      Voltage detector IC: 2.8V±1%, -Reset ODO, Rdt=400ms
      Source
      Published code list

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

    • BU4939FVoltage supervisor, ROHMVoltage supervisorROHM
      What it is
      Voltage supervisor
      Maker
      ROHM
      Package
      Not recorded
      Pins
      Not recorded
      Details
      CMOS-IC: Voltage Detector 3,9V, Reset Push-pull output
      Source
      Published code list

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

    • BU4939FWEVoltage supervisor, ROHMVoltage supervisorROHM
      What it is
      Voltage supervisor
      Maker
      ROHM
      Package
      Not recorded
      Pins
      Not recorded
      Details
      CMOS-IC: Voltage Detector 3,9V, Reset Push-pull output
      Source
      Published code list

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

    • BU4939GVoltage supervisor, ROHMVoltage supervisorROHM
      What it is
      Voltage supervisor
      Maker
      ROHM
      Package
      Not recorded
      Pins
      Not recorded
      Details
      CMOS-IC: Voltage Detector 3,9V, Reset Push-pull output
      Source
      Published code list

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

    • IXD5109N08ANVoltage supervisor, IXYSVoltage supervisorIXYS
      What it is
      Voltage supervisor
      Maker
      IXYS
      Package
      Not recorded
      Pins
      Not recorded
      Details
      Voltage detector IC: 0.8V±2%, +Reset ODO
      Source
      Published code list

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

    • IXD5120C282NR-GVoltage supervisor, IXYSVoltage supervisorIXYS
      What it is
      Voltage supervisor
      Maker
      IXYS
      Package
      Not recorded
      Pins
      Not recorded
      Details
      Voltage detector IC: 2.8V±2% -Reset PPO
      Source
      Published code list

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

    • IXD5127C52CNRVoltage supervisor, IXYSVoltage supervisorIXYS
      What it is
      Voltage supervisor
      Maker
      IXYS
      Package
      Not recorded
      Pins
      Not recorded
      Details
      Voltage detector IC: 5.2V±0.8%, -Reset PPO, -MR, 200ms Rt delay
      Source
      Published code list

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

    • IXD5127N52HNRVoltage supervisor, IXYSVoltage supervisorIXYS
      What it is
      Voltage supervisor
      Maker
      IXYS
      Package
      Not recorded
      Pins
      Not recorded
      Details
      Voltage detector IC: 5.2V±0.8%, +Reset ODO, -MR, 200ms Rt delay
      Source
      Published code list

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

    • KDZ4.7VVYZener diode, KECZener diodeKEC
      What it is
      Zener diode
      Maker
      KEC
      Package
      Not recorded
      Pins
      Not recorded
      Details
      Zener diode: 4.55..4.75V, Izt=5mA, Zzt=120, 100mW
      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.

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.

RF amplifier

Voltage, board powered, on the output pin that the bias resistor or choke feeds.

Working, it reads

The output pin sits at the device voltage the datasheet gives, a few volts, below the supply.

Dead, it reads

  • Output pin at 0 V, or near 0 Ω to ground with the power off: shorted inside.
  • Output pin at the full supply voltage: open inside, no current flowing.
On the board:
Measured on the board with power on; the bias network is part of the reading.
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 figures depend on the part and its bias resistor. 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.

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.

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.

Codes that begin with KY

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

Codes not listed here are printed on 44 more parts.

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