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SMD code Y0

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.

9 parts are printed Y0

Not sure which one you have?

Answer up to 4 quick questions and these 9 parts are ranked, with a meter test that settles it. It works on a dead part too.

  • MMBZ5221BSOT-23Zener diode, 3 pins, Formosa MicrosemiZener diodeSOT-233 pinsFormosa Microsemi
    What it is
    Zener diode
    Maker
    Formosa Microsemi
    Package
    SOT-23
    Pins
    3
    Source
    Manufacturer datasheet

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

  • AD8223MSOP-88 pins, Analog DevicesNot recordedMSOP-88 pinsAnalog Devices
    What it is
    Not recorded
    Maker
    Analog Devices
    Package
    MSOP-8
    Pins
    8
    Details
    Single-Supply, Low Cost Instrumentation Amplifier
    Source
    Published code list

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

  • ELM7640LBBSOT-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: 4.0V±2%, -Reset PPO, Rdt=500ms
    Source
    Published code list

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

  • R1210N502CSOT-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: PWM step-up DC-DC converter, 5V, 100KHz
    Source
    Published code list

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

  • R3111Q501CSOT-1434 pins, Nisshinbo Micro DevicesNot recordedSOT-1434 pinsNisshinbo Micro Devices
    What it is
    Not recorded
    Maker
    Nisshinbo Micro Devices
    Package
    SOT-143
    Pins
    4
    Details
    CMOS-IC: Voltage Detector 5V±2.0%, Reset Open drain output
    Source
    Published code list

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

  • RT9711CGBGSOT-23-55 pins, RichtekNot recordedSOT-23-55 pinsRichtek
    What it is
    Not recorded
    Maker
    Richtek
    Package
    SOT-23-5
    Pins
    5
    Details
    High-side power switch IC: Vin=2.5..5.5V, 0.6A, +CE
    Source
    Published code list

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

  • 3 more parts have no package on record
    • CGY121BInfineonNot recordedNot recordedNot recordedInfineon
      What it is
      Not recorded
      Maker
      Infineon
      Package
      Not recorded
      Pins
      Not recorded
      Details
      GaAs MMIC
      Source
      Published code list

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

    • R1163D301DNisshinbo Micro DevicesNot recordedNot recordedNot recordedNisshinbo Micro Devices
      What it is
      Not recorded
      Maker
      Nisshinbo Micro Devices
      Package
      Not recorded
      Pins
      Not recorded
      Details
      VR-IC: LDO, CE, auto-discharge, 3V±1.5%, 150mA
      Source
      Published code list

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

    • XC6225A32ANR-GLDO regulator, TorexLDO regulatorNot recordedNot recordedTorex
      What it is
      LDO regulator
      Maker
      Torex
      Package
      Not recorded
      Pins
      Not recorded
      Details
      Linear voltage regulator IC: LDO, 3.25V±2%, 30mA, +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.

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.

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.

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.

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.

Printed with a code easy to misread as Y0

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 5 more parts.

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