SMD code UD in SOT-343
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.
1 part in SOT-343 is printed UD
Not sure which one you have?
Answer up to 4 quick questions and these 23 parts are ranked, with a meter test that settles it. It works on a dead part too.
R1114Q331DSOT-343RicohNot recordedRicoh
- What it is
- Not recorded
- Maker
- Ricoh
- Package
- SOT-343
- Pins
- 4
- Details
- VR-IC: LDO, LN, CE, auto discharge, 3.3V±2%, 150mA
- Source
- Published code list
Is it dead? The meter test is below: Voltage regulator.
14 more parts have no package on record. Nothing rules them out, so they stay.
LESD08L3.3CESD protection diode, LRCESD protection diodeLRC
- What it is
- ESD protection diode
- Maker
- LRC
- Package
- Not recorded
- Pins
- Not recorded
- Details
- ESD protection diode, VRWM 3.3 V, IR @VRWM 0.5 μA, VBR Min 4 V
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: TVS or ESD protection diode.
RQ1E050RPHZGP-channel MOSFET, ROHMP-channel MOSFETROHM
- What it is
- P-channel MOSFET
- Maker
- ROHM
- Package
- Not recorded
- Pins
- Not recorded
- Details
- Pch -30V -5A Small Signal MOSFET
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: P-channel MOSFET.
RQ7E050RPP-channel MOSFET, ROHMP-channel MOSFETROHM
- What it is
- P-channel MOSFET
- Maker
- ROHM
- Package
- Not recorded
- Pins
- Not recorded
- Details
- P-channel -30V -5A Power MOSFET
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: P-channel MOSFET.
2SC4973DNPN transistor, PanasonicNPN transistorPanasonic
- What it is
- NPN transistor
- Maker
- Panasonic
- Package
- Not recorded
- Pins
- Not recorded
- Details
- NPN transistor: HF, 20V, 15mA, 650MHz, B=120..260
- Source
- Published code list
Is it dead? The meter test is below: NPN transistor.
2SK115ToshibaNot recordedToshiba
- What it is
- Not recorded
- Maker
- Toshiba
- Package
- Not recorded
- Pins
- 4
- Source
- Published code list
Is it dead? The meter test is below: This part.
AP7341D-32FS4-7LDO regulator, Diodes IncorporatedLDO regulatorDiodes Incorporated
- What it is
- LDO regulator
- Maker
- Diodes Incorporated
- Package
- Not recorded
- Pins
- Not recorded
- Details
- Linear voltage regulator IC: LDO, 3.2V±1%, 300mA, +CE, CL
- Source
- Published code list
Is it dead? The meter test is below: Voltage regulator.
APE8865U4-18LDO regulator, Advanced Power ElectronicsLDO regulatorAdvanced Power Electronics
- What it is
- LDO regulator
- Maker
- Advanced Power Electronics
- Package
- Not recorded
- Pins
- Not recorded
- Details
- Linear voltage regulator IC: LDO, 1.8±2%, 300mA, +CE
- Source
- Published code list
Is it dead? The meter test is below: Voltage regulator.
AX6608-18SCLDO regulator, AXElite TechnologyLDO regulatorAXElite Technology
- What it is
- LDO regulator
- Maker
- AXElite Technology
- Package
- Not recorded
- Pins
- Not recorded
- Details
- Linear voltage regulator IC: LDO, 1.8V±2%, 300mA, +CE
- Source
- Published code list
Is it dead? The meter test is below: Voltage regulator.
BCR151L3Digital transistor (PNP, resistors built in), InfineonDigital transistor (PNP, resistors built in)Infineon
- What it is
- Digital transistor (PNP, resistors built in)
- Maker
- Infineon
- Package
- Not recorded
- Pins
- Not recorded
- Details
- Si-pnp-Digi: Sw, 50V, 100mA, 250mW, R1/R2=100k/100k, 120MHz
- Source
- Published code list
Is it dead? The meter test is below: Digital transistor.
BD53E60GVoltage supervisorVoltage supervisorNot recorded
- What it is
- Voltage supervisor
- Maker
- Not recorded
- Package
- Not recorded
- Pins
- Not recorded
- Details
- Free Delay Time Setting CMOS Voltage Detector IC
- Source
- Published code list
Is it dead? The meter test is below: Integrated circuit.
BD53E60G-MVoltage supervisor, ROHMVoltage supervisorROHM
- What it is
- Voltage supervisor
- Maker
- ROHM
- Package
- Not recorded
- Pins
- Not recorded
- Details
- Voltage detector IC: 6.0V±1%, -Reset PPO
- Source
- Published code list
Is it dead? The meter test is below: Integrated circuit.
BD45271GVoltage supervisor, ROHMVoltage supervisorROHM
- What it is
- Voltage supervisor
- Maker
- ROHM
- Package
- Not recorded
- Pins
- Not recorded
- Details
- CMOS-IC: Voltage Detector 2,7V, -Reset Open drain output, 100ms
- Source
- Published code list
Is it dead? The meter test is below: Integrated circuit.
IXD5127C22JNRVoltage supervisor, IXYSVoltage supervisorIXYS
- What it is
- Voltage supervisor
- Maker
- IXYS
- Package
- Not recorded
- Pins
- Not recorded
- Details
- Voltage detector IC: 2.2V±0.8%, +Reset PPO, -MR, 400ms Rt delay
- Source
- Published code list
Is it dead? The meter test is below: Integrated circuit.
SM4T18CSGS-Thomson MicroelectronicsNot recordedSGS-Thomson Microelectronics
- What it is
- Not recorded
- Maker
- SGS-Thomson Microelectronics
- Package
- Not recorded
- Pins
- Not recorded
- Details
- TVS: 18V, 16A, 400W(1ms), Bidirectional
- Source
- Published code list
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.
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.
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.
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.
NPN transistor
Diode range, part lifted or its base leg off the pad.
Working, it reads
Red probe on the base reads about 0.6 to 0.75 V to the emitter and to the collector, and open the other way round. Collector to emitter reads open both ways.
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.
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.
Digital transistor
Ohms range, part lifted. The datasheet gives the built-in resistors: R1 in series with the base, R2 from base to emitter.
Working, it reads
Base to emitter reads about R1 plus R2 either way round, about 20 kΩ on a 10 k and 10 k part, give or take their wide tolerance. Collector to emitter reads open. A part with no R2 reads a junction behind R1 one way instead.
Dead, it reads
- Collector to emitter the same both ways, near 0 Ω with a continuous beep: shorted.
- From the base, open or far above R1 plus R2: R1 has failed. Static damage shows here most often.
- Base to emitter near 0 Ω: failed short.
- 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:
- The readings depend on the resistor values, so an identical part elsewhere on the board is the surest reference. Measure it the same way.
- Watch for:
- On the diode range a good part with 10 kΩ resistors reads open on every pair, so a good part looks dead there. Use the ohms range.
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.
Printed with a code easy to misread as UD
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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