SMD code U3-
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.
99 parts are printed U3-
Not sure which one you have?
Answer up to 4 quick questions and these 50 parts are ranked, with a meter test that settles it. It works on a dead part too.
WE05MUCSOT-883ESD protection diode, 3 pins, WayonESD protection diodeSOT-8833 pinsWayon
- What it is
- ESD protection diode
- Maker
- Wayon
- Package
- SOT-883
- Pins
- 3
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: TVS or ESD protection diode.
WE05MUC-ATSOT-883ESD protection diode, 3 pins, WayonESD protection diodeSOT-8833 pinsWayon
- What it is
- ESD protection diode
- Maker
- Wayon
- Package
- SOT-883
- Pins
- 3
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: TVS or ESD protection diode.
2SK613-3SOT-233 pins, SonyNot recordedSOT-233 pinsSony
- What it is
- Not recorded
- Maker
- Sony
- Package
- SOT-23
- Pins
- 3
- Details
- FET n-type: Vid-cam amp, 15V, 50mA, 150mW, Idss=19..30.2, Up<1.26V
- Source
- Published code list
Is it dead? The meter test is below: MOSFET.
AP2281-3FMGSOT-23-6Load switch, 6 pins, Diodes IncorporatedLoad switchSOT-23-66 pinsDiodes Incorporated
- What it is
- Load switch
- Maker
- Diodes Incorporated
- Package
- SOT-23-6
- Pins
- 6
- Details
- Single Slew Rate Controlled Load Switch
- Source
- Published code list
Is it dead? The meter test is below: Load switch.
AP2281-3WGSOT-23-6Load switch, 6 pins, Diodes IncorporatedLoad switchSOT-23-66 pinsDiodes Incorporated
- What it is
- Load switch
- Maker
- Diodes Incorporated
- Package
- SOT-23-6
- Pins
- 6
- Details
- Single Slew Rate Controlled Load Switch
- Source
- Published code list
Is it dead? The meter test is below: Load switch.
AP8822C-23GASOT-23Voltage supervisor, 3 pins, Anwell SemiconductorVoltage supervisorSOT-233 pinsAnwell Semiconductor
- What it is
- Voltage supervisor
- Maker
- Anwell Semiconductor
- Package
- SOT-23
- Pins
- 3
- Details
- Voltage detector IC: 2.3V±2%, -Reset PPO, Rdt=200ms, H-free
- Source
- Published code list
Is it dead? The meter test is below: Integrated circuit.
AP8822C-23GTSOT-323Voltage supervisor, 3 pins, Anwell SemiconductorVoltage supervisorSOT-3233 pinsAnwell Semiconductor
- What it is
- Voltage supervisor
- Maker
- Anwell Semiconductor
- Package
- SOT-323
- Pins
- 3
- Details
- Voltage detector IC: 2.3V±2%, -Reset PPO, Rdt=200ms, H-free
- Source
- Published code list
Is it dead? The meter test is below: Integrated circuit.
AP8822C-23PASOT-23Voltage supervisor, 3 pins, Anwell SemiconductorVoltage supervisorSOT-233 pinsAnwell Semiconductor
- What it is
- Voltage supervisor
- Maker
- Anwell Semiconductor
- Package
- SOT-23
- Pins
- 3
- Details
- Voltage detector IC: 2.3V±2%, -Reset PPO, Rdt=200ms
- Source
- Published code list
Is it dead? The meter test is below: Integrated circuit.
7 more parts have no package on record
TST052-411WSchottky diode, Taitron ComponentsSchottky diodeNot recordedNot recordedTaitron Components
- What it is
- Schottky diode
- Maker
- Taitron Components
- Package
- Not recorded
- Pins
- Not recorded
- Details
- Schottky Barrier Diodes (Multiple Terminals)
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Schottky diode.
TST054-411WSSchottky diode, Taitron ComponentsSchottky diodeNot recordedNot recordedTaitron Components
- What it is
- Schottky diode
- Maker
- Taitron Components
- Package
- Not recorded
- Pins
- Not recorded
- Details
- Schottky Barrier Diodes (Multiple Terminals)
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Schottky diode.
VBUS054B-HSFESD protection diode, VishayESD protection diodeNot recordedNot recordedVishay
- What it is
- ESD protection diode
- Maker
- Vishay
- Package
- Not recorded
- Pins
- Not recorded
- Details
- 4-Line BUS-Port ESD Protection
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: TVS or ESD protection diode.
AP7341D-15FS4-7LDO regulator, Diodes IncorporatedLDO regulatorNot recordedNot recordedDiodes Incorporated
- What it is
- LDO regulator
- Maker
- Diodes Incorporated
- Package
- Not recorded
- Pins
- Not recorded
- Details
- Linear voltage regulator IC: LDO, 1.5V±1%, 300mA, +CE, CL
- Source
- Published code list
Is it dead? The meter test is below: Voltage regulator.
AP8822C-23GIVoltage supervisor, Anwell SemiconductorVoltage supervisorNot recordedNot recordedAnwell Semiconductor
- What it is
- Voltage supervisor
- Maker
- Anwell Semiconductor
- Package
- Not recorded
- Pins
- Not recorded
- Details
- Voltage detector IC: 2.3V±2%, -Reset PPO, 200ms Rt delay, H-free
- Source
- Published code list
Is it dead? The meter test is below: Integrated circuit.
AP8822C-23GSVoltage supervisor, Anwell SemiconductorVoltage supervisorNot recordedNot recordedAnwell Semiconductor
- What it is
- Voltage supervisor
- Maker
- Anwell Semiconductor
- Package
- Not recorded
- Pins
- Not recorded
- Details
- Voltage detector IC: 2.3V±2%, -Reset PPO, 200ms Rt delay, H-free
- Source
- Published code list
Is it dead? The meter test is below: Integrated circuit.
AP8822C-23PIVoltage supervisor, Anwell SemiconductorVoltage supervisorNot recordedNot recordedAnwell Semiconductor
- What it is
- Voltage supervisor
- Maker
- Anwell Semiconductor
- Package
- Not recorded
- Pins
- Not recorded
- Details
- Voltage detector IC: 2.3V±2%, -Reset PPO, 200ms Rt delay
- 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.
Schottky diode
Diode range, part lifted or one leg off the pad. Red probe on the anode.
Working, it reads
About 0.15 to 0.45 V anode to cathode, roughly half a silicon diode, and open the other way.
Dead, it reads
- The same reading both ways round, near 0 V with a continuous beep or the same middling value: shorted.
- A reading the wrong way round as well: leaky.
- Open both ways: failed open.
- 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 large Schottky can read about 0.1 V forward and beep like a short, and leaks a little the wrong way when good, more when warm. It is shorted only if it reads the same both ways. Measure it cold, beside an identical cold one.
A dead part still carries its marking. A short or an open says it has failed, not that it is a different part.
TVS or ESD protection diode
Diode range, from the protected line to ground, part lifted if you can.
Working, it reads
A one-way part reads about 0.6 to 0.8 V forward and open in reverse. A two-way part reads open both ways. Arrays with several lines read as the datasheet's diagram draws them.
Dead, it reads
- From the line to ground, the same reading both ways, near 0 V with a continuous beep: shorted.
- A reading both ways on a one-way part: leaky.
- A one-way part open both ways: failed open.
- On the board
- , a line reading shorted to ground can be this part or anything else on that line. Lift it: if the short goes with it, it has failed.
- Compare:
- The same part on the next line or connector pin is the healthy reading to compare with.
- Watch for:
- A two-way part reads open both ways when it is good, exactly like one that has failed open. The meter cannot tell them apart; an identical part on the next line can.
A dead part still carries its marking. A short or an open says it has failed, not that it is a different part.
MOSFET
Diode range, part lifted. Test drain to source first, then short gate to source and test again.
Working, it reads
One way between drain and source reads about 0.4 to 0.9 V, the body diode, and the other way open. The gate reads open to both other pins.
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.
- No body diode at all: failed open.
- On the board
- the gate usually has a resistor to the source, which reads as that resistor and 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.
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.
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.
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