SMD code U in SOT-23
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 SOT-23 are printed U
Not sure which one you have?
Answer up to 4 quick questions and these 24 parts are ranked, with a meter test that settles it. It works on a dead part too.
IRLML6344SOT-23N-channel MOSFET, 3 pins, InfineonN-channel MOSFET3 pinsInfineon
- What it is
- N-channel MOSFET
- Maker
- Infineon
- Package
- SOT-23
- Pins
- 3
- Details
- 30V Single N-Channel StrongIRFET™ Power MOSFET in a SOT-23 package
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: N-channel MOSFET.
2SB852KSOT-233 pins, ROHMNot recorded3 pinsROHM
- What it is
- Not recorded
- Maker
- ROHM
- Package
- SOT-23
- Pins
- 3
- Details
- pnp darlington comp 2SD1383K
- Source
- Published code list
Is it dead? The meter test is below: Darlington transistor.
IRLML6344TRPbFSOT-23N-channel MOSFET, 3 pins, International RectifierN-channel MOSFET3 pinsInternational Rectifier
- What it is
- N-channel MOSFET
- Maker
- International Rectifier
- Package
- SOT-23
- Pins
- 3
- Details
- MOSFET n-type: Sw, fast, 30V, 4A, 1.3W, Rds=20m(4.5V), 4.2/22ns
- Source
- Published code list
Is it dead? The meter test is below: N-channel MOSFET.
12 more parts have no package on record. Nothing rules them out, so they stay.
AOZ8S321UD4-03ESD protection diode, Alpha & Omega SemiconductorESD protection diodeNot recordedAlpha & Omega Semiconductor
- What it is
- ESD protection diode
- Maker
- Alpha & Omega Semiconductor
- Package
- Not recorded
- Pins
- Not recorded
- Details
- ESD protection for high-speed interfaces
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: TVS or ESD protection diode.
AOZ8S321UD4-05ESD protection diode, Alpha & Omega SemiconductorESD protection diodeNot recordedAlpha & Omega Semiconductor
- What it is
- ESD protection diode
- Maker
- Alpha & Omega Semiconductor
- Package
- Not recorded
- Pins
- Not recorded
- Details
- ESD protection for high-speed interfaces
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: TVS or ESD protection diode.
AOZ8S507BDS-07ESD protection diode, Alpha & Omega SemiconductorESD protection diodeNot recordedAlpha & Omega Semiconductor
- What it is
- ESD protection diode
- Maker
- Alpha & Omega Semiconductor
- Package
- Not recorded
- Pins
- Not recorded
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: TVS or ESD protection diode.
AOZ8S530BLS-05ESD protection diode, Alpha & Omega SemiconductorESD protection diodeNot recordedAlpha & Omega Semiconductor
- What it is
- ESD protection diode
- Maker
- Alpha & Omega Semiconductor
- Package
- Not recorded
- Pins
- Not recorded
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: TVS or ESD protection diode.
AOZ8310ADI-04ESD protection diode, Alpha & Omega SemiconductorESD protection diodeNot recordedAlpha & Omega Semiconductor
- What it is
- ESD protection diode
- Maker
- Alpha & Omega Semiconductor
- Package
- Not recorded
- Pins
- Not recorded
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: TVS or ESD protection diode.
AOZ8851ADI-18ESD protection diode, Alpha & Omega SemiconductorESD protection diodeNot recordedAlpha & Omega Semiconductor
- What it is
- ESD protection diode
- Maker
- Alpha & Omega Semiconductor
- Package
- Not recorded
- Pins
- Not recorded
- Details
- ESD protection for high-speed interfaces
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: TVS or ESD protection diode.
GSEN3U003ESD protection diode, Good-ArkESD protection diodeNot recordedGood-Ark
- What it is
- ESD protection diode
- Maker
- Good-Ark
- Package
- Not recorded
- Pins
- Not recorded
- Details
- ESD protection diode, VRWM 3.6 V
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: TVS or ESD protection diode.
GSEN3U303ESD protection diode, Good-ArkESD protection diodeNot recordedGood-Ark
- What it is
- ESD protection diode
- Maker
- Good-Ark
- Package
- Not recorded
- Pins
- Not recorded
- Details
- ESD protection diode, VRWM 3.3 V
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: TVS or ESD protection diode.
GSEN5U003ESD protection diode, Good-ArkESD protection diodeNot recordedGood-Ark
- What it is
- ESD protection diode
- Maker
- Good-Ark
- Package
- Not recorded
- Pins
- Not recorded
- Details
- ESD protection diode, VRWM 5 V
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: TVS or ESD protection diode.
LESD11D3.3CA1ESD protection diode, LRCESD protection diodeNot recordedLRC
- What it is
- ESD protection diode
- Maker
- LRC
- Package
- Not recorded
- Pins
- Not recorded
- Details
- ESD protection diode, VRWM 3.3 V, IR @VRWM 0.2 μA, VBR Min 3.7 V
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: TVS or ESD protection diode.
PESD3V3Z1BSFESD protection diode, 2 pins, NexperiaESD protection diode2 pinsNexperia
- What it is
- ESD protection diode
- Maker
- Nexperia
- Package
- Not recorded
- Pins
- 2
- Details
- Extremely low capacitance bidirectional ESD protection diode
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: TVS or ESD protection diode.
PESD4V0Z1BSFESD protection diode, 2 pins, NexperiaESD protection diode2 pinsNexperia
- What it is
- ESD protection diode
- Maker
- Nexperia
- Package
- Not recorded
- Pins
- 2
- Details
- Extremely low capacitance bidirectional ESD protection diode
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: TVS or ESD protection diode.
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.
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.
Darlington transistor
Diode range, part lifted or its base leg off the pad.
Working, it reads
From the base, one probe colour reads about 0.6 to 0.75 V to the collector and about 1.1 to 1.4 V to the emitter, two junctions in series, and open the other way round. Collector to emitter reads open. Built-in resistors can change these readings.
Dead, it reads
- Collector to emitter the same both ways, near 0 V with a continuous beep: shorted. The commonest failure.
- The base the same both ways to another pin, near 0 V or a middling value: a shorted junction.
- Only one junction reads, or none: a junction has failed open. It then looks like a diode.
- A reading the wrong way round, where it should be open: 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 pair of diodes with a common pin reads just like a transistor, and some transistors carry a built-in diode or resistor. The datasheet says which.
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.
Codes that begin with U
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 1,527 more parts.
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