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SMD code FM7

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.

8 parts are printed FM7

Not sure which one you have?

Answer up to 4 quick questions and these 8 parts are ranked, with a meter test that settles it. It works on a dead part too.

  • FM4937SMARectifier, 2 pins, LRCRectifierSMA2 pinsLRC
    What it is
    Rectifier
    Maker
    LRC
    Package
    SMA
    Pins
    2
    Details
    Rectifier, VPK 600 V, IO @ TL 1 A, TL@°C 75
    Source
    Manufacturer datasheet

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

  • FP6861E-C3AS5CSOT-23-5Load switch, 5 pins, FitipowerLoad switchSOT-23-55 pinsFitipower
    What it is
    Load switch
    Maker
    Fitipower
    Package
    SOT-23-5
    Pins
    5
    Details
    Single-Channel Power Distribution Switch
    Source
    Manufacturer datasheet

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

  • IXD5122F737MR-GSOT-23-5Voltage supervisor, 5 pins, IXYSVoltage supervisorSOT-23-55 pinsIXYS
    What it is
    Voltage supervisor
    Maker
    IXYS
    Package
    SOT-23-5
    Pins
    5
    Details
    Voltage detector IC: 3.7V±2%, -Reset ODO, +WDEN, PUR, Wt=800ms, Rdt=400ms
    Source
    Published code list

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

  • XC66DC5957MSOT-23-55 pins, TorexNot recordedSOT-23-55 pinsTorex
    What it is
    Not recorded
    Maker
    Torex
    Package
    SOT-23-5
    Pins
    5
    Details
    Linear voltage regulator with volatge detector: LDO, 5.7V±2%, 100mA, Vdet=5.9V±2%, +Reset PPO
    Source
    Published code list

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

  • XC66DN5957MSOT-23-55 pins, TorexNot recordedSOT-23-55 pinsTorex
    What it is
    Not recorded
    Maker
    Torex
    Package
    SOT-23-5
    Pins
    5
    Details
    Linear voltage regulator with volatge detector: LDO, 5.7V±2%, 100mA, Vdet=5.9V±2%, +Reset ODO
    Source
    Published code list

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

  • XC6122F737MR-GSOT-23-5Voltage supervisor, 5 pins, TorexVoltage supervisorSOT-23-55 pinsTorex
    What it is
    Voltage supervisor
    Maker
    Torex
    Package
    SOT-23-5
    Pins
    5
    Details
    Voltage detector IC: 3.7V±2%, -Reset ODO, +WDEN, PUR, Wt=800ms, Rdt=400ms
    Source
    Published code list

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

  • XC6225B43AMR-GSOT-23-5LDO regulator, 5 pins, TorexLDO regulatorSOT-23-55 pinsTorex
    What it is
    LDO regulator
    Maker
    Torex
    Package
    SOT-23-5
    Pins
    5
    Details
    Linear voltage regulator IC: LDO, 4.35V±2%, 30mA, +CE, CL
    Source
    Published code list

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

  • 1 more part has no package on record
    • XC6225B43AGR-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, 4.35V±2%, 30mA, +CE, CL
      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.

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.

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.

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.

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 FM7

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

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