WhatSMD: identify an unknown SMD component

Not sure which one you have?

Answer up to 4 quick questions and these 7 parts are ranked, with a meter test that settles it. It works on a dead part too.

The only part printed 8P in this package in our tables

TLV74115PDQN

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.

Datasheet

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.

SMAJ16Aprinted BPSMATVS diode, 2 pins, VishayTVS diode2 pinsVishay
Printed BP on the part. Easy to misread as 8P. Check that character with a loupe before you order anything.
What it is
TVS diode
Maker
Vishay
Package
SMA
Pins
2
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 SMAJ16A, opens in a new tab
5 more parts have no package on record. Nothing rules them out, so they stay.
- AOZ1331ADIprinted BPLoad switch, Alpha & Omega SemiconductorLoad switchNot recordedAlpha & Omega Semiconductor
  Printed BP on the part. Easy to misread as 8P. Check that character with a loupe before you order anything.
  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
- BGA616printed BPRF amplifier (MMIC), InfineonRF amplifier (MMIC)Not recordedInfineon
  Printed BP on the part. Easy to misread as 8P. Check that character with a loupe before you order anything.
  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
- BZX884B56Lprinted BPZener diode, VishayZener diodeNot recordedVishay
  Printed BP on the part. Easy to misread as 8P. Check that character with a loupe before you order anything.
  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
- MSMP16Aprinted BPTVS diode, VishayTVS diodeNot recordedVishay
  Printed BP on the part. Easy to misread as 8P. Check that character with a loupe before you order anything.
  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
- SMP16Aprinted BPTVS diode, VishayTVS diodeNot recordedVishay
  Printed BP on the part. Easy to misread as 8P. Check that character with a loupe before you order anything.
  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

10 more parts have codes that begin with 8P

Codes that begin with 8P

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

SML4738printed 8P2SMAZener diode, 2 pins, VishayZener diode2 pinsVishay
Printed 8P2. Only the start matches what you typed, so this fits only if the rest of the marking is worn off.
What it is
Zener diode
Maker
Vishay
Package
SMA
Pins
2
Details
8.2 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 SML4738, opens in a new tab
SML4738Aprinted 8P2ASMAZener diode, 2 pins, VishayZener diode2 pinsVishay
Printed 8P2A. Only the start matches what you typed, so this fits only if the rest of the marking is worn off.
What it is
Zener diode
Maker
Vishay
Package
SMA
Pins
2
Details
8.2 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 SML4738A, opens in a new tab
P4SMA27Aprinted BPJSMATVS diode, 2 pins, Taiwan SemiconductorTVS diode2 pinsTaiwan Semiconductor
Printed BPJ. 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
Taiwan Semiconductor
Package
SMA
Pins
2
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 P4SMA27A, opens in a new tab
TPSMA27Aprinted BPPSMATVS diode, 2 pins, VishayTVS diode2 pinsVishay
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
SMA
Pins
2
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 TPSMA27A, opens in a new tab
6 more parts have no package on record. Nothing rules them out, so they stay.
- 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
- 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

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.

What’s printed on it?

TLV74115PDQN

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?

Codes that begin with 8P

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?

Is it dead?

One code, several parts

When more than one is left

When you cannot read it