SMD code 34 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.
5 parts in SOT-23 are printed 34
Not sure which one you have?
Answer up to 4 quick questions and these 32 parts are ranked, with a meter test that settles it. It works on a dead part too.
BFT25ASOT-23RF transistor, 3 pins, NXPRF transistor3 pinsNXP
- What it is
- RF transistor
- Maker
- NXP
- Package
- SOT-23
- Pins
- 3
- Details
- NPN 5 GHz wideband transistor
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Bipolar transistor.
MMBD1405SOT-23Switching diode, 3 pins, Taitron ComponentsSwitching diode3 pinsTaitron Components
- What it is
- Switching diode
- Maker
- Taitron Components
- Package
- SOT-23
- Pins
- 3
- Details
- SMD Switching Diodes (Three Terminals)
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Silicon diode.
2SC5007-FBSOT-233 pins, NEC ElectronicsNot recorded3 pinsNEC Electronics
- What it is
- Not recorded
- Maker
- NEC Electronics
- Package
- SOT-23
- Pins
- 3
- Details
- Si-npn: UHF/VHF, 20V, 65mA, 125mW, 7GHz, B=80..160
- Source
- Published code list
Is it dead? The meter test is below: This part.
ELM9834BBSOT-233 pins, ELM TechnologyNot recorded3 pinsELM Technology
- What it is
- Not recorded
- Maker
- ELM Technology
- Package
- SOT-23
- Pins
- 3
- Details
- Linear voltage regulator IC: 3.4V±2%, 200mA
- Source
- Published code list
Is it dead? The meter test is below: Voltage regulator.
NE68119-FBSOT-233 pins, California Eastern LaboratoriesNot recorded3 pinsCalifornia Eastern Laboratories
- What it is
- Not recorded
- Maker
- California Eastern Laboratories
- Package
- SOT-23
- Pins
- 3
- Details
- Si-npn: UHF/VHF, 20V, 65mA, 125mW, 7GHz, B=80..160
- Source
- Published code list
Is it dead? The meter test is below: This part.
10 more parts have no package on record. Nothing rules them out, so they stay.
BFCN-1575+RF filter, Mini-CircuitsRF filterNot recordedMini-Circuits
- What it is
- RF filter
- Maker
- Mini-Circuits
- Package
- Not recorded
- Pins
- Not recorded
- Details
- LTCC filter, 1530-1620 MHz
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: This part.
CDBMHT340-HFSchottky diode, ComchipSchottky diodeNot recordedComchip
- What it is
- Schottky diode
- Maker
- Comchip
- Package
- Not recorded
- Pins
- Not recorded
- Details
- 40 V, 3 A Schottky barrier diode
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Schottky diode.
CHSDCDJGPSchottky diode, ChenmkoSchottky diodeNot recordedChenmko
- What it is
- Schottky diode
- Maker
- Chenmko
- Package
- Not recorded
- Pins
- Not recorded
- Details
- SCHOTTKY BARRIER RECTIFIER, 40 V, 3.0 A
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Schottky diode.
CHSDCDJGP-ASchottky diode, ChenmkoSchottky diodeNot recordedChenmko
- What it is
- Schottky diode
- Maker
- Chenmko
- Package
- Not recorded
- Pins
- Not recorded
- Details
- SCHOTTKY BARRIER RECTIFIER, 40 V, 3.0 A
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Schottky diode.
ET3164Load switch, ETEKLoad switchNot recordedETEK
- What it is
- Load switch
- Maker
- ETEK
- Package
- Not recorded
- Pins
- Not recorded
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Load switch.
FM340-MHTSchottky diode, Formosa MicrosemiSchottky diodeNot recordedFormosa Microsemi
- What it is
- Schottky diode
- Maker
- Formosa Microsemi
- Package
- Not recorded
- Pins
- Not recorded
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Schottky diode.
FM340-MHT-Q1Schottky diode, Formosa MicrosemiSchottky diodeNot recordedFormosa Microsemi
- What it is
- Schottky diode
- Maker
- Formosa Microsemi
- Package
- Not recorded
- Pins
- Not recorded
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Schottky diode.
FM340-MST-Q1Schottky diode, Formosa MicrosemiSchottky diodeNot recordedFormosa Microsemi
- What it is
- Schottky diode
- Maker
- Formosa Microsemi
- Package
- Not recorded
- Pins
- Not recorded
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Schottky diode.
FMOSAE0P75N02AE-HMOSFET, Formosa MicrosemiMOSFETNot recordedFormosa Microsemi
- What it is
- MOSFET
- Maker
- Formosa Microsemi
- Package
- Not recorded
- Pins
- Not recorded
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: MOSFET.
FMOSAE0P75N02E-HMOSFET, Formosa MicrosemiMOSFETNot recordedFormosa Microsemi
- What it is
- MOSFET
- Maker
- Formosa Microsemi
- Package
- Not recorded
- Pins
- Not recorded
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: MOSFET.
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.
Bipolar 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 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.
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.
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.
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.
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.
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.
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.
Codes that begin with 34
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 428 more parts.
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