SMD code BCs
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.
The last letter, s, is lower case, which on NXP and Philips parts is a date or factory code, so it was set aside and BC was searched.
146 parts are printed BCs
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.
ABCX54-10-HFSOT-89NPN transistor, 3 pins, ComchipNPN transistorSOT-893 pinsComchip
- What it is
- NPN transistor
- Maker
- Comchip
- Package
- SOT-89
- Pins
- 3
- Details
- 45 V, 1 A NPN transistor
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: NPN transistor.
ACPDV8V0-HFSOD-323ESD protection diode, 2 pins, ComchipESD protection diodeSOD-3232 pinsComchip
- What it is
- ESD protection diode
- Maker
- Comchip
- Package
- SOD-323
- Pins
- 2
- Details
- 8 V bidirectional ESD protection diode
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: TVS or ESD protection diode.
ACPDV8V0A-HFSOD-323ESD protection diode, 2 pins, ComchipESD protection diodeSOD-3232 pinsComchip
- What it is
- ESD protection diode
- Maker
- Comchip
- Package
- SOD-323
- Pins
- 2
- Details
- 8 V bidirectional ESD protection diode
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: TVS or ESD protection diode.
AO3442SOT-23MOSFET, 3 pins, Alpha & Omega SemiconductorMOSFETSOT-233 pinsAlpha & Omega Semiconductor
- What it is
- MOSFET
- Maker
- Alpha & Omega Semiconductor
- Package
- SOT-23
- Pins
- 3
- Details
- Medium-voltage (40-400 V) MOSFET
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: MOSFET.
AO3442LSOT-23MOSFET, 3 pins, Alpha & Omega SemiconductorMOSFETSOT-233 pinsAlpha & Omega Semiconductor
- What it is
- MOSFET
- Maker
- Alpha & Omega Semiconductor
- Package
- SOT-23
- Pins
- 3
- Details
- Medium-voltage (40-400 V) MOSFET
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: MOSFET.
BAS40CGPSOT-23Schottky diode, 3 pins, ChenmkoSchottky diodeSOT-233 pinsChenmko
- What it is
- Schottky diode
- Maker
- Chenmko
- Package
- SOT-23
- Pins
- 3
- Details
- SCHOTTKY DIODE, 40 V, 0.2 A
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Schottky diode.
BCW61CSOT-23PNP transistor, 3 pins, InfineonPNP transistorSOT-233 pinsInfineon
- What it is
- PNP transistor
- Maker
- Infineon
- Package
- SOT-23
- Pins
- 3
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: PNP transistor.
BCX54-10SOT-89NPN transistor, 3 pins, InfineonNPN transistorSOT-893 pinsInfineon
- What it is
- NPN transistor
- Maker
- Infineon
- Package
- SOT-89
- Pins
- 3
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: NPN transistor.
BV08CSOD-323ESD protection diode, 2 pins, YFWESD protection diodeSOD-3232 pinsYFW
- What it is
- ESD protection diode
- Maker
- YFW
- Package
- SOD-323
- Pins
- 2
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: TVS or ESD protection diode.
BZT52H-C5V6SOD-123FZener diode, 2 pins, NexperiaZener diodeSOD-123F2 pinsNexperia
- What it is
- Zener diode
- Maker
- Nexperia
- Package
- SOD-123F
- Pins
- 2
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Zener diode.
CDBF40-HFSOD-323Schottky diode, 2 pins, ComchipSchottky diodeSOD-3232 pinsComchip
- What it is
- Schottky diode
- Maker
- Comchip
- Package
- SOD-323
- Pins
- 2
- Details
- 40 V, 0.2 A Schottky barrier diode
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Schottky diode.
4 more parts have no package on record
ACDBQC40-HFSchottky diode, ComchipSchottky diodeNot recordedNot recordedComchip
- What it is
- Schottky diode
- Maker
- Comchip
- Package
- Not recorded
- Pins
- Not recorded
- Details
- 40 V, 0.2 A Schottky barrier diode
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Schottky diode.
ACDBUC40-HFSchottky diode, ComchipSchottky diodeNot recordedNot recordedComchip
- What it is
- Schottky diode
- Maker
- Comchip
- Package
- Not recorded
- Pins
- Not recorded
- Details
- 40 V, 0.2 A Schottky barrier diode
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Schottky diode.
CDBQC40-HFSchottky diode, ComchipSchottky diodeNot recordedNot recordedComchip
- What it is
- Schottky diode
- Maker
- Comchip
- Package
- Not recorded
- Pins
- Not recorded
- Details
- 40 V, 0.2 A Schottky barrier diode
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Schottky diode.
CDBU40-HFSchottky diode, ComchipSchottky diodeNot recordedNot recordedComchip
- What it is
- Schottky diode
- Maker
- Comchip
- Package
- Not recorded
- Pins
- Not recorded
- Details
- 40 V, 0.2 A Schottky barrier diode
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Schottky 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.
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.
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.
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.
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.
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.
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.
Printed with a code easy to misread as BCs
One character differs, and it is one that is easy to confuse under a lamp. Each code has a page of its own.
Codes not listed here are printed on 112 more parts.
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