SMD code search: identify a part by its marking

Not sure which one you have?

Answer up to 4 quick questions and these 10 parts are ranked, with a meter test that settles it. It works on a dead part too.

The only part printed BLSB in our tables

TC1301BLSBVMF

What it is: Not recorded
Maker: Microchip
Package: DFN
Pins: Not recorded
Details: Linear voltage regulator with volatge detector: LDO, Dual out, Vo1/Vo2=2.2V(300mA)/1.5V(150mA)±2.5%, Vdet=2.2V±2.5%, +CE
Source: Published code list

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.

Was it this one?

Printed with a code easy to misread

These parts are printed with a character that is easy to misread as what you typed. The odd one out is marked on each.

1SMA5915Bprinted 815BSMAZener diode, 2 pins, onsemiZener diodeSMA2 pinsonsemi
Printed 815B on the part. Easy to misread as BLSB. Check that character with a loupe before you order anything.
What it is
Zener diode
Maker
onsemi
Package
SMA
Pins
2
Source
Manufacturer 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
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 1SMA5915B, opens in a new tab
DS1815-10printed 815BSOT-233 pins, Analog DevicesNot recordedSOT-233 pinsAnalog Devices
Printed 815B on the part. Easy to misread as BLSB. Check that character with a loupe before you order anything.
What it is
Not recorded
Maker
Analog Devices
Package
SOT-23
Pins
3
Details
CMOS-IC: Voltage Detector 3,3V±5%, -Reset Push-pull output
Source
Published code list
Is it dead?
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.
EC8908-15BW1printed 815BWSONLDO regulator, E-CMOSLDO regulatorWSONNot recordedE-CMOS
Printed 815B on the part. Easy to misread as BLSB. Check that character with a loupe before you order anything.
What it is
LDO regulator
Maker
E-CMOS
Package
WSON
Pins
Not recorded
Details
Linear voltage regulator IC: LDO, 1.5V±1.5%, 700mA, +CE
Source
Published code list
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.
EC890815BC5printed 815BSOT-353LDO regulator, 5 pins, E-CMOSLDO regulatorSOT-3535 pinsE-CMOS
Printed 815B on the part. Easy to misread as BLSB. Check that character with a loupe before you order anything.
What it is
LDO regulator
Maker
E-CMOS
Package
SOT-353
Pins
5
Details
Linear voltage regulator IC: LDO, 1.5V±1.5%, 700mA, +CE
Source
Published code list
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.
R1161D152Bprinted B15BSONNisshinbo Micro DevicesNot recordedSONNot recordedNisshinbo Micro Devices
Printed B15B on the part. Easy to misread as BLSB. Check that character with a loupe before you order anything.
What it is
Not recorded
Maker
Nisshinbo Micro Devices
Package
SON
Pins
Not recorded
Details
VR-IC: LDO, CE, 1.5V±2%, 350mA
Source
Published code list
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.
TC1301BISBVMFprinted BISBDFNMicrochipNot recordedDFNNot recordedMicrochip
Printed BISB on the part. Easy to misread as BLSB. Check that character with a loupe before you order anything.
What it is
Not recorded
Maker
Microchip
Package
DFN
Pins
Not recorded
Details
Linear voltage regulator with volatge detector: LDO, Dual out, Vo1/Vo2=2.5V(300mA)/1.5V(150mA)±2.5%, Vdet=2.2V±2.5%, +CE
Source
Published code list
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.
3 more parts have no package on record
- EC890815BC7printed 815BLDO regulator, E-CMOSLDO regulatorNot recordedNot recordedE-CMOS
  Printed 815B on the part. Easy to misread as BLSB. Check that character with a loupe before you order anything.
  What it is
  LDO regulator
  Maker
  E-CMOS
  Package
  Not recorded
  Pins
  Not recorded
  Details
  Linear voltage regulator IC: LDO, 1.5V±1.5%, 700mA, +CE
  Source
  Published code list
  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.
- R1172S151Bprinted B15BNisshinbo Micro DevicesNot recordedNot recordedNot recordedNisshinbo Micro Devices
  Printed B15B on the part. Easy to misread as BLSB. Check that character with a loupe before you order anything.
  What it is
  Not recorded
  Maker
  Nisshinbo Micro Devices
  Package
  Not recorded
  Pins
  Not recorded
  Details
  VR-IC: LDO, CE, 1.5V±2%, 1A
  Source
  Published code list
  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.
- R1525S100Bprinted B15BRicohNot recordedNot recordedNot recordedRicoh
  Printed B15B on the part. Easy to misread as BLSB. Check that character with a loupe before you order anything.
  What it is
  Not recorded
  Maker
  Ricoh
  Package
  Not recorded
  Pins
  Not recorded
  Details
  Linear voltage regulator IC: 10.0V±0.6%, 200mA, +CE
  Source
  Published code list
  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.

1 more part has a code that begins with BLSB

Codes that begin with BLSB

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

BTB1580L3printed B1580SOT-223PNP transistor, 4 pins, CYStekPNP transistorSOT-2234 pinsCYStek
Printed B1580. Only the start matches what you typed, so this fits only if the rest of the marking is worn off.
What it is
PNP transistor
Maker
CYStek
Package
SOT-223
Pins
4
Details
-120 V, -4 A PNP transistor
Source
Manufacturer datasheet
Is it dead?
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.
Datasheetfor BTB1580L3, opens in a new tab

Did you find your part?

One code, several parts

Marking codes are not unique. In the standard code book, 6H on a SOT-23 is an NPN transistor, a varicap, an N-channel JFET, two digital transistors, a 3.6 V voltage detector: six parts from five makers. So a search shows the parts we hold under that code and under codes easily misread as it, with only the columns that tell them apart.

6Hon a SOT-23, in the code book

NPN transistor
Varicap
N-channel JFET
Digital transistor ×2
3.6 V voltage detector

When more than one is left

Tap Help me choose. Up to 4 quick answers: whether the part has failed, then what separates the parts left. Those get ranked with the reasoning and a test that settles it. That uses one identification: 2 a month are free without an account, and 3 with a free account.

When you cannot read it

Tap the camera in the field. We read the characters, keep the ones we are unsure of, and search every reading. A photo too soft to read is turned back on your phone first; if it is the only one you can get, you can still send it.

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SMD code search: identify a part by its marking

What’s printed on it?

TC1301BLSBVMF

Is it dead?

Printed with a code easy to misread

Is it dead?

Is it dead?

Is it dead?

Is it dead?

Is it dead?

Is it dead?

Is it dead?

Is it dead?

Is it dead?

Codes that begin with BLSB

Is it dead?

Did you find your part?

One code, several parts

When more than one is left

When you cannot read it

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