SMD code W9 in SOT-23-5
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-23-5 are printed W9
Not sure which one you have?
Answer up to 4 quick questions and these 17 parts are ranked, with a meter test that settles it. It works on a dead part too.
FMW9SOT-23-55 pins, ROHMNot recorded5 pinsROHM
- What it is
- Not recorded
- Maker
- ROHM
- Package
- SOT-23-5
- Pins
- 5
- Details
- Si-npn: Dual, HF, 20V, 50mA, >1400MHz
- Source
- Published code list
Is it dead? The meter test is below: This part.
R1210N391DSOT-23-55 pins, Nisshinbo Micro DevicesNot recorded5 pinsNisshinbo Micro Devices
- What it is
- Not recorded
- Maker
- Nisshinbo Micro Devices
- Package
- SOT-23-5
- Pins
- 5
- Details
- VR-IC: PWM step-up DC-DC converter, 3,9V, 180KHz
- Source
- Published code list
Is it dead? The meter test is below: Integrated circuit.
RT9193-17PBSOT-23-5LDO regulator, 5 pins, RichtekLDO regulator5 pinsRichtek
- What it is
- LDO regulator
- Maker
- Richtek
- Package
- SOT-23-5
- Pins
- 5
- Details
- 300mA, Ultra-Low Noise, Ultra-Fast CMOS LDO Regulator
- Source
- Published code list
Is it dead? The meter test is below: Voltage regulator.
12 more parts have no package on record. Nothing rules them out, so they stay.
BCR42PNDigital transistor (resistors built in), InfineonDigital transistor (resistors built in)Not recordedInfineon
- What it is
- Digital transistor (resistors built in)
- Maker
- Infineon
- Package
- Not recorded
- Pins
- Not recorded
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Digital transistor.
BZT52B5V1HEZener diode, Galaxy MicroelectronicsZener diodeNot recordedGalaxy Microelectronics
- What it is
- Zener diode
- Maker
- Galaxy Microelectronics
- Package
- Not recorded
- Pins
- Not recorded
- Details
- 5.1V, 2%, Surface Mount Zener Diodes
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Zener diode.
MM3Z5V6CWZener diode, Yangjie Electronic TechZener diodeNot recordedYangjie Electronic Tech
- What it is
- Zener diode
- Maker
- Yangjie Electronic Tech
- Package
- Not recorded
- Pins
- Not recorded
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Zener diode.
VS28VUA1LBTVS diode, ROHMTVS diodeNot recordedROHM
- What it is
- TVS diode
- Maker
- ROHM
- Package
- Not recorded
- Pins
- Not recorded
- Details
- Transient Voltage Suppressor
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: TVS or ESD protection diode.
1SS423ToshibaNot recordedNot recordedToshiba
- What it is
- Not recorded
- Maker
- Toshiba
- Package
- Not recorded
- Pins
- Not recorded
- Details
- Diode: Dual, Sw, 40V, 100mA, Vf<0.62V(100mA), 15pF
- Source
- Published code list
Is it dead? The meter test is below: Silicon diode.
AP8822C-39GIVoltage supervisor, Anwell SemiconductorVoltage supervisorNot recordedAnwell Semiconductor
- What it is
- Voltage supervisor
- Maker
- Anwell Semiconductor
- Package
- Not recorded
- Pins
- Not recorded
- Details
- Voltage detector IC: 3.9V±2%, -Reset PPO, 200ms Rt delay, H-free
- Source
- Published code list
Is it dead? The meter test is below: Integrated circuit.
AP8822C-39GSVoltage supervisor, Anwell SemiconductorVoltage supervisorNot recordedAnwell Semiconductor
- What it is
- Voltage supervisor
- Maker
- Anwell Semiconductor
- Package
- Not recorded
- Pins
- Not recorded
- Details
- Voltage detector IC: 3.9V±2%, -Reset PPO, 200ms Rt delay, H-free
- Source
- Published code list
Is it dead? The meter test is below: Integrated circuit.
AP8822C-39PIVoltage supervisor, Anwell SemiconductorVoltage supervisorNot recordedAnwell Semiconductor
- What it is
- Voltage supervisor
- Maker
- Anwell Semiconductor
- Package
- Not recorded
- Pins
- Not recorded
- Details
- Voltage detector IC: 3.9V±2%, -Reset PPO, 200ms Rt delay
- Source
- Published code list
Is it dead? The meter test is below: Integrated circuit.
AP8822C-39PSVoltage supervisor, Anwell SemiconductorVoltage supervisorNot recordedAnwell Semiconductor
- What it is
- Voltage supervisor
- Maker
- Anwell Semiconductor
- Package
- Not recorded
- Pins
- Not recorded
- Details
- Voltage detector IC: 3.9V±2%, -Reset PPO, 200ms Rt delay
- Source
- Published code list
Is it dead? The meter test is below: Integrated circuit.
BD46411GVoltage supervisor, ROHMVoltage supervisorNot recordedROHM
- What it is
- Voltage supervisor
- Maker
- ROHM
- Package
- Not recorded
- Pins
- Not recorded
- Details
- CMOS-IC: Voltage Detector 4,1V, -Reset Push-pull output, 100ms
- Source
- Published code list
Is it dead? The meter test is below: Integrated circuit.
DPA05PIN diode, Sanyo ElectricPIN diodeNot recordedSanyo Electric
- What it is
- PIN diode
- Maker
- Sanyo Electric
- Package
- Not recorded
- Pins
- Not recorded
- Details
- PIN diode: Dual, FM/AM-tun, AGC, 50V, 50mA, Vf=0.95V(50mA), 0.25pF
- Source
- Published code list
Is it dead? The meter test is below: PIN diode or varicap.
EC95810C39C7IVoltage supervisor, E-CMOSVoltage supervisorNot recordedE-CMOS
- What it is
- Voltage supervisor
- Maker
- E-CMOS
- Package
- Not recorded
- Pins
- Not recorded
- Details
- Voltage detector IC: 3.9V±2%, -Reset PPO, Td=200ms
- 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.
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.
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.
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.
Zener diode
Diode range for the forward check, part lifted, red probe on the anode. A bench supply for the Zener voltage.
Working, it reads
About 0.6 to 0.8 V forward and open in reverse on the diode range. Its Zener voltage shows only on a supply: feed it through a resistor that sets about 5 mA, cathode to positive, read quickly, and it should hold near its rated voltage.
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, forward too: failed open.
- Holds well off its rated voltage on the supply test: drifted.
- A soft knee, or a voltage that creeps on the supply test: 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 meter's diode range stops at about 2 to 3 V, so almost every Zener reads open in reverse on it, good or bad; a 3 V meter may just show a 2.4 or 2.7 V part. Above about 3 V the meter cannot tell a Zener from a plain diode.
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.
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.
PIN diode or varicap
Diode range, part lifted or one leg off the pad. Red probe on the anode.
Working, it reads
About 0.6 to 0.9 V anode to cathode, 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.
- 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 varicap that has drifted in capacitance reads normal on a meter. Only a capacitance meter or the tuning itself shows 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 W9
For a marking with its end worn or burnt off. Each code has a page of its own.
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