SMD code BB in SOT-523
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-523 is printed BB
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.
15 parts have no package on record. Nothing rules them out, so they stay.
TSFB13LSchottky diode, Taitron ComponentsSchottky diodeNot recordedTaitron Components
- What it is
- Schottky diode
- Maker
- Taitron Components
- Package
- Not recorded
- Pins
- Not recorded
- Details
- Surface Mount Schottky Rectifiers
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Schottky diode.
TSS0230USchottky diode, Taiwan SemiconductorSchottky diodeNot recordedTaiwan Semiconductor
- What it is
- Schottky diode
- Maker
- Taiwan Semiconductor
- Package
- Not recorded
- Pins
- Not recorded
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Schottky diode.
USFB13LSchottky diode, KECSchottky diodeNot recordedKEC
- What it is
- Schottky diode
- Maker
- KEC
- Package
- Not recorded
- Pins
- Not recorded
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Schottky diode.
2SB831-BPNP transistor, HitachiPNP transistorNot recordedHitachi
- What it is
- PNP transistor
- Maker
- Hitachi
- Package
- Not recorded
- Pins
- Not recorded
- Details
- PNP transistor: AF-Amp, 25V, 700mA, 150mW, B=85..170
- Source
- Published code list
Is it dead? The meter test is below: PNP transistor.
AAT3221IJS-1.8LDO regulator, SkyworksLDO regulatorNot recordedSkyworks
- What it is
- LDO regulator
- Maker
- Skyworks
- Package
- Not recorded
- Pins
- Not recorded
- Details
- Linear voltage regulator IC: LDO, 1.8V±2%, 150mA, +CE
- Source
- Published code list
Is it dead? The meter test is below: Voltage regulator.
AP2301FGEGLoad switch, Diodes IncorporatedLoad switchNot recordedDiodes Incorporated
- What it is
- Load switch
- Maker
- Diodes Incorporated
- Package
- Not recorded
- Pins
- Not recorded
- Details
- Power switch
- Source
- Published code list
Is it dead? The meter test is below: Load switch.
BD48E38GVoltage supervisor, ROHMVoltage supervisorNot recordedROHM
- What it is
- Voltage supervisor
- Maker
- ROHM
- Package
- Not recorded
- Pins
- Not recorded
- Details
- Voltage detector
- Source
- Published code list
Is it dead? The meter test is below: Integrated circuit.
BD48K38GVoltage supervisor, ROHMVoltage supervisorNot recordedROHM
- What it is
- Voltage supervisor
- Maker
- ROHM
- Package
- Not recorded
- Pins
- Not recorded
- Details
- Voltage detector
- Source
- Published code list
Is it dead? The meter test is below: Integrated circuit.
BU18TA2WHFVLDO regulator, ROHMLDO regulatorNot recordedROHM
- What it is
- LDO regulator
- Maker
- ROHM
- Package
- Not recorded
- Pins
- Not recorded
- Details
- Linear voltage regulator IC: LDO, 1.8V±1%, 200mA, +CE
- Source
- Published code list
Is it dead? The meter test is below: Voltage regulator.
BU45K422GVoltage supervisor, ROHMVoltage supervisorNot recordedROHM
- What it is
- Voltage supervisor
- Maker
- ROHM
- Package
- Not recorded
- Pins
- Not recorded
- Details
- Voltage detector IC: 4.2V±1%, -Reset ODO, Rdt=200ms
- Source
- Published code list
Is it dead? The meter test is below: Integrated circuit.
FSA3157LFairchild SemiconductorNot recordedNot recordedFairchild Semiconductor
- What it is
- Not recorded
- Maker
- Fairchild Semiconductor
- Package
- Not recorded
- Pins
- Not recorded
- Details
- CMOS logic IC: 2-channel analog multiplexer/demultiplexer
- Source
- Published code list
Is it dead? The meter test is below: Integrated circuit.
IXD5127C17GNRVoltage supervisor, IXYSVoltage supervisorNot recordedIXYS
- What it is
- Voltage supervisor
- Maker
- IXYS
- Package
- Not recorded
- Pins
- Not recorded
- Details
- Voltage detector IC: 1.7V±0.8%,+Reset PPO, -MR, 100ms Rt delay
- Source
- Published code list
Is it dead? The meter test is below: Integrated circuit.
IXD5127N18BNRVoltage supervisor, IXYSVoltage supervisorNot recordedIXYS
- What it is
- Voltage supervisor
- Maker
- IXYS
- Package
- Not recorded
- Pins
- Not recorded
- Details
- Voltage detector IC: 1.8V±0.8%, -Reset ODO, -MR, 100ms Rt delay
- Source
- Published code list
Is it dead? The meter test is below: Integrated circuit.
NC7SB31576 pins, onsemiNot recorded6 pinsonsemi
- What it is
- Not recorded
- Maker
- onsemi
- Package
- Not recorded
- Pins
- 6
- Source
- Published code list
Is it dead? The meter test is below: This part.
NC7SB3157LFairchild SemiconductorNot recordedNot recordedFairchild Semiconductor
- What it is
- Not recorded
- Maker
- Fairchild Semiconductor
- Package
- Not recorded
- Pins
- Not recorded
- Details
- CMOS logic IC: 2-channel analog multiplexer/demultiplexer
- 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.
PNP transistor
Diode range, part lifted or its base leg off the pad.
Working, it reads
Black 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.
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.
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.
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.
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.
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