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SMD code 420

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.

20 parts are printed 420

Not sure which one you have?

Answer up to 4 quick questions and these 20 parts are ranked, with a meter test that settles it. It works on a dead part too.

  • HM1132B31MRSOT-23-5LDO regulator, 5 pins, Huamei SemiconductorLDO regulatorSOT-23-55 pinsHuamei Semiconductor
    What it is
    LDO regulator
    Maker
    Huamei Semiconductor
    Package
    SOT-23-5
    Pins
    5
    Details
    Linear voltage regulator IC: LDO, 3.1V±2%, 100mA, +CE
    Source
    Published code list

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

  • LN1152A312MRSOT-23-5LDO regulator, 5 pins, Shanghai Natlinear ElectronicsLDO regulatorSOT-23-55 pinsShanghai Natlinear Electronics
    What it is
    LDO regulator
    Maker
    Shanghai Natlinear Electronics
    Package
    SOT-23-5
    Pins
    5
    Details
    Linear voltage regulator IC: LDO, 3.1V±2%, 100mA, +CE, PDR
    Source
    Published code list

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

  • R1114N201ASOT-23-55 pins, Nisshinbo Micro DevicesNot recordedSOT-23-55 pinsNisshinbo Micro Devices
    What it is
    Not recorded
    Maker
    Nisshinbo Micro Devices
    Package
    SOT-23-5
    Pins
    5
    Details
    VR-IC: LDO, LN, -CE, 2V±2%, 150mA
    Source
    Published code list

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

  • R1191N020BSOT-23-5LDO regulator, 5 pins, RicohLDO regulatorSOT-23-55 pinsRicoh
    What it is
    LDO regulator
    Maker
    Ricoh
    Package
    SOT-23-5
    Pins
    5
    Details
    Linear voltage regulator IC: LDO, 2.0V±1.5%, 300mA, +CE, ECO
    Source
    Published code list

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

  • TK15420MSOIC-88 pins, Toko AmericaNot recordedSOIC-88 pinsToko America
    What it is
    Not recorded
    Maker
    Toko America
    Package
    SOIC-8
    Pins
    8
    Details
    Linear IC: 5V, 75, 6dB, dual video line driver
    Source
    Published code list

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

  • 10 more parts have no package on record
    • FDC6420CP-channel MOSFET, onsemiP-channel MOSFETNot recordedNot recordedonsemi
      What it is
      P-channel MOSFET
      Maker
      onsemi
      Package
      Not recorded
      Pins
      Not recorded
      Details
      MOSFET - N & P-Channel, POWERTRENCH
      Source
      Manufacturer datasheet

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

    • FDMA420NZN-channel MOSFET, onsemiN-channel MOSFETNot recordedNot recordedonsemi
      What it is
      N-channel MOSFET
      Maker
      onsemi
      Package
      Not recorded
      Pins
      Not recorded
      Details
      MOSFET - Single, N-Channel, 2.5 V, Specified, POWERTRENCH
      Source
      Manufacturer datasheet

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

    • TCK420GLoad switch, ToshibaLoad switchNot recordedNot recordedToshiba
      What it is
      Load switch
      Maker
      Toshiba
      Package
      Not recorded
      Pins
      Not recorded
      Details
      TCK42xG Series
      Source
      Manufacturer datasheet

      Is it dead? The meter test is below: Load switch.

    • AT-420354 pins, BroadcomNot recordedNot recorded4 pinsBroadcom
      What it is
      Not recorded
      Maker
      Broadcom
      Package
      Not recorded
      Pins
      4
      Source
      Published code list

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

    • AT-420364 pins, BroadcomNot recordedNot recorded4 pinsBroadcom
      What it is
      Not recorded
      Maker
      Broadcom
      Package
      Not recorded
      Pins
      4
      Source
      Published code list

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

    • AT-420854 pins, BroadcomNot recordedNot recorded4 pinsBroadcom
      What it is
      Not recorded
      Maker
      Broadcom
      Package
      Not recorded
      Pins
      4
      Source
      Published code list

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

    • AT-420864 pins, BroadcomNot recordedNot recorded4 pinsBroadcom
      What it is
      Not recorded
      Maker
      Broadcom
      Package
      Not recorded
      Pins
      4
      Source
      Published code list

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

    • AT42086BroadcomNot recordedNot recordedNot recordedBroadcom
      What it is
      Not recorded
      Maker
      Broadcom
      Package
      Not recorded
      Pins
      Not recorded
      Details
      med pwr RF to 6GHz
      Source
      Published code list

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

    • TK65420MDC-DC converter, Toko AmericaDC-DC converterNot recordedNot recordedToko America
      What it is
      DC-DC converter
      Maker
      Toko America
      Package
      Not recorded
      Pins
      Not recorded
      Details
      DC/DC voltage converter IC: PCA, st-dwn, 2.0V±3%, 100mA, Vbat monitor
      Source
      Published code list

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

    • VRH4201NVLDO regulator, AnaSemLDO regulatorNot recordedNot recordedAnaSem
      What it is
      LDO regulator
      Maker
      AnaSem
      Package
      Not recorded
      Pins
      Not recorded
      Details
      Linear voltage regulator IC: LDO, 4.2V±1%, 250mA, +CE
      Source
      Published code list

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

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.

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.

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.

Load switch

Voltage, board powered, black probe on ground.

Working, it reads

Switched on, the output pin sits at the input voltage. Switched off, it sits near 0 V.

Dead, it reads

  • Output at the input voltage while switched off: the pass element has shorted.
  • Input present and switched on, no output: failed open, or shut down into a shorted load. Power off and measure output to ground.
On the board:
An output near 0 Ω to ground is usually the load. Lift the output pin to see which.
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 pinout and whether the enable is active high or low differ between parts. 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.

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.

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.

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.

Printed with a code easy to misread as 420

One character differs, and it is one that is easy to confuse under a lamp. Each code has a page of its own.

Codes not listed here are printed on 2 more parts.

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