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SMD code JQ in DFN

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.

3 parts in DFN are printed JQ

Not sure which one you have?

Answer up to 4 quick questions and these 13 parts are ranked, with a meter test that settles it. It works on a dead part too.

  • R3116K451ADFNVoltage supervisor, RicohVoltage supervisorRicoh
    What it is
    Voltage supervisor
    Maker
    Ricoh
    Package
    DFN
    Pins
    Not recorded
    Details
    Voltage detector IC: 4.5V±0.8%, -Reset ODO
    Source
    Published code list

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

  • RP107K241BDFNLDO regulator, RicohLDO regulatorRicoh
    What it is
    LDO regulator
    Maker
    Ricoh
    Package
    DFN
    Pins
    Not recorded
    Details
    Linear voltage regulator IC: LDO, 2.4V±1%, 200mA, +CE
    Source
    Published code list

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

  • UM1550DB-22DFNLDO regulator, Union SemiconductorLDO regulatorUnion Semiconductor
    What it is
    LDO regulator
    Maker
    Union Semiconductor
    Package
    DFN
    Pins
    Not recorded
    Details
    Linear voltage regulator IC: LDO, 2.2V±2%, 200mA
    Source
    Published code list

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

  • 10 more parts have no package on record. Nothing rules them out, so they stay.
    • BFCN-1262+RF filter, Mini-CircuitsRF filterMini-Circuits
      What it is
      RF filter
      Maker
      Mini-Circuits
      Package
      Not recorded
      Pins
      Not recorded
      Details
      LTCC filter, 12100-13200 MHz
      Source
      Manufacturer datasheet

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

    • NCP171A3MX170165LDO regulator, onsemiLDO regulatoronsemi
      What it is
      LDO regulator
      Maker
      onsemi
      Package
      Not recorded
      Pins
      Not recorded
      Details
      LDO Regulator - Ultra-Low Iq, Dual Power Mode
      Source
      Manufacturer datasheet

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

    • RQ7E055ATP-channel MOSFET, ROHMP-channel MOSFETROHM
      What it is
      P-channel MOSFET
      Maker
      ROHM
      Package
      Not recorded
      Pins
      Not recorded
      Details
      Pch -30V -5.5A Middle Power MOSFET
      Source
      Manufacturer datasheet

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

    • 2SJ579Sanyo ElectricNot recordedSanyo Electric
      What it is
      Not recorded
      Maker
      Sanyo Electric
      Package
      Not recorded
      Pins
      Not recorded
      Details
      p-MOS*-e: Sw, U-Speed, LogL, 60V, 1,2A, 1.5W, <0.8Ω(0,6A), 8/22ns
      Source
      Published code list

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

    • BU4847FVoltage supervisor, ROHMVoltage supervisorROHM
      What it is
      Voltage supervisor
      Maker
      ROHM
      Package
      Not recorded
      Pins
      Not recorded
      Details
      CMOS-IC: Voltage Detector 4,7V, -Reset Open drain output
      Source
      Published code list

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

    • BU4847FWEVoltage supervisor, ROHMVoltage supervisorROHM
      What it is
      Voltage supervisor
      Maker
      ROHM
      Package
      Not recorded
      Pins
      Not recorded
      Details
      CMOS-IC: Voltage Detector 4,7V, -Reset Open drain output
      Source
      Published code list

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

    • BU4847GVoltage supervisor, ROHMVoltage supervisorROHM
      What it is
      Voltage supervisor
      Maker
      ROHM
      Package
      Not recorded
      Pins
      Not recorded
      Details
      CMOS-IC: Voltage Detector 4,7V, -Reset Open drain output
      Source
      Published code list

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

    • PT7M6101CHC4EVoltage supervisorVoltage supervisorNot recorded
      What it is
      Voltage supervisor
      Maker
      Not recorded
      Package
      Not recorded
      Pins
      Not recorded
      Details
      Ultra Low Voltage Detectors
      Source
      Published code list

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

    • PT7M6101CHNEVoltage supervisorVoltage supervisorNot recorded
      What it is
      Voltage supervisor
      Maker
      Not recorded
      Package
      Not recorded
      Pins
      Not recorded
      Details
      Ultra Low Voltage Detectors
      Source
      Published code list

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

    • PT7M6101CHTAEVoltage supervisorVoltage supervisorNot recorded
      What it is
      Voltage supervisor
      Maker
      Not recorded
      Package
      Not recorded
      Pins
      Not recorded
      Details
      Voltage Detector
      Source
      Published code list

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

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.

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.

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.

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.

Printed with a code easy to misread as JQ

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

Codes that begin with JQ

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 43 more parts.

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