SMD marking

BPin 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.

6 parts are printed BP

Not sure which one you have?

Answer up to 4 quick questions and these 6 parts are ranked, with a meter test that settles it. It works on a dead part too.

AO3451SOT-23P-channel MOSFET, 3 pins, Alpha & Omega SemiconductorP-channel MOSFET3 pinsAlpha & Omega Semiconductor
What it is
P-channel MOSFET
Maker
Alpha & Omega Semiconductor
Package
SOT-23
Pins
3
Details
P-channel MOSFET (8-60 V)
Source
From the manufacturer's datasheet
Is it dead?
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:
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.
Datasheetfor AO3451, opens in a new tab
5 more parts have no package on record. Nothing rules them out, so they stay.
- AOZ1331ADILoad switch, Alpha & Omega SemiconductorLoad switchNot recordedAlpha & Omega Semiconductor
  What it is
  Load switch
  Maker
  Alpha & Omega Semiconductor
  Package
  Not recorded
  Pins
  Not recorded
  Details
  Smart load switch
  Source
  From the manufacturer's datasheet
  Is it dead?
  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.
  Datasheetfor AOZ1331ADI, opens in a new tab
- BGA616RF amplifier (MMIC), InfineonRF amplifier (MMIC)Not recordedInfineon
  What it is
  RF amplifier (MMIC)
  Maker
  Infineon
  Package
  Not recorded
  Pins
  Not recorded
  Source
  From the manufacturer's datasheet
  Is it dead?
  Voltage, board powered, on the output pin that the bias resistor or choke feeds.
  Working, it reads
  The output pin sits at the device voltage the datasheet gives, a few volts, below the supply.
  Dead, it reads
  Output pin at 0 V, or near 0 Ω to ground with the power off: shorted inside.
  Output pin at the full supply voltage: open inside, no current flowing.
  On the board:
  Measured on the board with power on; the bias network is part of the reading.
  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 figures depend on the part and its bias resistor. 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.
  Datasheetfor BGA616, opens in a new tab
- BZX884B56LZener diode, VishayZener diodeNot recordedVishay
  What it is
  Zener diode
  Maker
  Vishay
  Package
  Not recorded
  Pins
  Not recorded
  Details
  56 V Zener diode
  Source
  From the manufacturer's datasheet
  Is it dead?
  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:
  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.
  Datasheetfor BZX884B56L, opens in a new tab
- MSMP16ATVS diode, VishayTVS diodeNot recordedVishay
  What it is
  TVS diode
  Maker
  Vishay
  Package
  Not recorded
  Pins
  Not recorded
  Details
  150 W TVS diode, unidirectional
  Source
  From the manufacturer's datasheet
  Is it dead?
  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:
  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.
  Datasheetfor MSMP16A, opens in a new tab
- SMP16ATVS diode, VishayTVS diodeNot recordedVishay
  What it is
  TVS diode
  Maker
  Vishay
  Package
  Not recorded
  Pins
  Not recorded
  Details
  400 W TVS diode, unidirectional
  Source
  From the manufacturer's datasheet
  Is it dead?
  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:
  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.
  Datasheetfor SMP16A, opens in a new tab

1 more part is printed with a code easy to misread as BP

Printed with a code easy to misread

One character differs, and it is one that is easy to confuse under a lamp. The odd one out is marked on each.

TLV74115PDQNprinted 8PLDO regulator, 4 pins, Texas InstrumentsLDO regulator4 pinsTexas Instruments
Printed 8P on the part. Easy to misread as BP. Check that character with a loupe before you order anything.
What it is
LDO regulator
Maker
Texas Instruments
Package
Not recorded
Pins
4
Details
150-mA, Low-Dropout Regulator With Foldback Current Limit
Source
From the manufacturer's datasheet
Is it dead?
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.
Datasheetfor TLV74115PDQN, opens in a new tab

7 more parts have codes that begin with BP

Codes that begin with BP

For a marking with its end worn or burnt off. Each one shows its full printed code.

BC817DPN-AUprinted 8PNSOT-23Transistor, 3 pins, PanjitTransistor3 pinsPanjit
Printed 8PN. Only the start matches what you typed, so this fits only if the rest of the marking is worn off.
What it is
Transistor
Maker
Panjit
Package
SOT-23
Pins
3
Details
Bipolar transistor
Source
From the manufacturer's datasheet
Is it dead?
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:
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.
Datasheetfor BC817DPN-AU, opens in a new tab
6 more parts have no package on record. Nothing rules them out, so they stay.
- TA6F27Aprinted BPPTVS diode, VishayTVS diodeNot recordedVishay
  Printed BPP. Only the start matches what you typed, so this fits only if the rest of the marking is worn off.
  What it is
  TVS diode
  Maker
  Vishay
  Package
  Not recorded
  Pins
  Not recorded
  Details
  600 W TVS diode, unidirectional
  Source
  From the manufacturer's datasheet
  Is it dead?
  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:
  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.
  Datasheetfor TA6F27A, opens in a new tab
- TA6F27CAprinted BPPTVS diode, VishayTVS diodeNot recordedVishay
  Printed BPP. Only the start matches what you typed, so this fits only if the rest of the marking is worn off.
  What it is
  TVS diode
  Maker
  Vishay
  Package
  Not recorded
  Pins
  Not recorded
  Details
  600 W TVS diode, bidirectional
  Source
  From the manufacturer's datasheet
  Is it dead?
  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:
  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.
  Datasheetfor TA6F27CA, opens in a new tab
- TA6L27Aprinted BPLTVS diode, VishayTVS diodeNot recordedVishay
  Printed BPL. Only the start matches what you typed, so this fits only if the rest of the marking is worn off.
  What it is
  TVS diode
  Maker
  Vishay
  Package
  Not recorded
  Pins
  Not recorded
  Details
  600 W TVS diode, unidirectional
  Source
  From the manufacturer's datasheet
  Is it dead?
  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:
  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.
  Datasheetfor TA6L27A, opens in a new tab
- TA6L27CAprinted BPLTVS diode, VishayTVS diodeNot recordedVishay
  Printed BPL. Only the start matches what you typed, so this fits only if the rest of the marking is worn off.
  What it is
  TVS diode
  Maker
  Vishay
  Package
  Not recorded
  Pins
  Not recorded
  Details
  600 W TVS diode, bidirectional
  Source
  From the manufacturer's datasheet
  Is it dead?
  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:
  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.
  Datasheetfor TA6L27CA, opens in a new tab
- TPSMP27Aprinted BPPTVS diode, VishayTVS diodeNot recordedVishay
  Printed BPP. Only the start matches what you typed, so this fits only if the rest of the marking is worn off.
  What it is
  TVS diode
  Maker
  Vishay
  Package
  Not recorded
  Pins
  Not recorded
  Details
  400 W TVS diode, unidirectional
  Source
  From the manufacturer's datasheet
  Is it dead?
  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:
  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.
  Datasheetfor TPSMP27A, opens in a new tab
- BC817DPNprinted 8PNTransistor, PanjitTransistorNot recordedPanjit
  Printed 8PN. Only the start matches what you typed, so this fits only if the rest of the marking is worn off.
  What it is
  Transistor
  Maker
  Panjit
  Package
  Not recorded
  Pins
  Not recorded
  Details
  Bipolar transistor
  Source
  From the manufacturer's datasheet
  Is it dead?
  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:
  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.
  Datasheetfor BC817DPN, opens in a new tab

Open this in the search to correct a character or try another package.

6 parts are printed BP

Is it dead?

Is it dead?

Is it dead?

Is it dead?

Is it dead?

Is it dead?

Printed with a code easy to misread

Is it dead?

Codes that begin with BP

Is it dead?

Is it dead?

Is it dead?

Is it dead?

Is it dead?

Is it dead?

Is it dead?