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SMD code KN

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.

4 parts are printed KN

Not sure which one you have?

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

  • 2SK3018SOT-23N-channel MOSFET, 3 pins, JSCJ
    What it is
    N-channel MOSFET
    Maker
    JSCJ
    Package
    SOT-23
    Pins
    3
    Details
    MOSFET, N-channel, 30 V, 0.1 A
    Source
    From the manufacturer's datasheet

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

    Datasheetfor 2SK3018, opens in a new tab
  • BAS316/DGSOD-323Switching diode, 2 pins, Nexperia
    What it is
    Switching diode
    Maker
    Nexperia
    Package
    SOD-323
    Pins
    2
    Pinout
    • 1 cathode
    • 2 anode
    Details
    High-speed switching diode, single (DG selection)
    Source
    From the manufacturer's datasheet

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

    Datasheetfor BAS316/DG, opens in a new tab
  • PMV48XPSOT-23P-channel MOSFET, 3 pins, Nexperia
    What it is
    P-channel MOSFET
    Maker
    Nexperia
    Package
    SOT-23
    Pins
    3
    Details
    20 V, 3.5 A P-channel Trench MOSFET
    Source
    From the manufacturer's datasheet

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

    Datasheetfor PMV48XP, opens in a new tab
  • TPS7A20285PDQNX2SONLDO regulator, 4 pins, Texas Instruments
    What it is
    LDO regulator
    Maker
    Texas Instruments
    Package
    X2SON
    Pins
    4
    Details
    300mA, Ultra-Low-Noise, Low-IQ, High PSRR LDO
    Source
    From the manufacturer's datasheet

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

    Datasheetfor TPS7A20285PDQN, opens in a new tab

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.

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.

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.

P-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 drain, black on the source: 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. 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.

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.

Codes that begin with KN

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

Open this in the search to correct a character or try another package.