WhatSMD: identify an unknown SMD component

Not sure which one you have?

Answer up to 4 quick questions and these 8 parts are ranked, with a meter test that settles it. It works on a dead part too.

The only part printed 6F in this package in our tables

BC818-25

What it is: Transistor
Maker: Infineon
Package: Not recorded
Pins: Not recorded
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.

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.

BCX69-10printed CFTransistor, InfineonTransistorNot recordedInfineon
Printed CF on the part. Easy to misread as 6F. Check that character with a loupe before you order anything.
What it is
Transistor
Maker
Infineon
Package
Not recorded
Pins
Not recorded
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 BCX69-10, opens in a new tab
BFR92Pprinted GFRF transistor, InfineonRF transistorNot recordedInfineon
Printed GF on the part. Easy to misread as 6F. Check that character with a loupe before you order anything.
What it is
RF transistor
Maker
Infineon
Package
Not recorded
Pins
Not recorded
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 BFR92P, opens in a new tab
BSS79Cprinted CFMOSFET, InfineonMOSFETNot recordedInfineon
Printed CF on the part. Easy to misread as 6F. Check that character with a loupe before you order anything.
What it is
MOSFET
Maker
Infineon
Package
Not recorded
Pins
Not recorded
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
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:
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.
Datasheetfor BSS79C, opens in a new tab
LP5907SNX-1.2printed CFLDO regulator, 4 pins, Texas InstrumentsLDO regulator4 pinsTexas Instruments
Printed CF on the part. Easy to misread as 6F. Check that character with a loupe before you order anything.
What it is
LDO regulator
Maker
Texas Instruments
Package
Not recorded
Pins
4
Details
250mA, Low-Noise, Low-IQ LDO
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 LP5907SNX-1.2, opens in a new tab
LP5907SNX1printed CFLDO regulator, 4 pins, Texas InstrumentsLDO regulator4 pinsTexas Instruments
Printed CF on the part. Easy to misread as 6F. Check that character with a loupe before you order anything.
What it is
LDO regulator
Maker
Texas Instruments
Package
Not recorded
Pins
4
Details
250mA, Low-Noise, Low-IQ LDO
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 LP5907SNX1, opens in a new tab
LP5907SNX1.2NOPBG4printed CFLDO regulator, 4 pins, Texas InstrumentsLDO regulator4 pinsTexas Instruments
Printed CF on the part. Easy to misread as 6F. Check that character with a loupe before you order anything.
What it is
LDO regulator
Maker
Texas Instruments
Package
Not recorded
Pins
4
Details
250mA, Low-Noise, Low-IQ LDO
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 LP5907SNX1.2NOPBG4, opens in a new tab
SN74AUP1G240DPWprinted CFLogic gate, 5 pins, Texas InstrumentsLogic gate5 pinsTexas Instruments
Printed CF on the part. Easy to misread as 6F. Check that character with a loupe before you order anything.
What it is
Logic gate
Maker
Texas Instruments
Package
Not recorded
Pins
5
Details
Low-Power Single Inverter With 3-State Output
Source
From the manufacturer's datasheet
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.
Datasheetfor SN74AUP1G240DPW, opens in a new tab

7 more parts have codes that begin with 6F

Codes that begin with 6F

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

SN74LVC2G14DCKprinted CF5SOT-363Logic gate, 6 pins, Texas InstrumentsLogic gate6 pinsTexas Instruments
Printed CF5. Only the start matches what you typed, so this fits only if the rest of the marking is worn off.
What it is
Logic gate
Maker
Texas Instruments
Package
SOT-363
Pins
6
Details
Dual Schmitt-Trigger Inverter
Source
From the manufacturer's datasheet
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.
Datasheetfor SN74LVC2G14DCK, opens in a new tab
6 more parts have no package on record. Nothing rules them out, so they stay.
- AOZ15333DI-01printed CF01Load switch, Alpha & Omega SemiconductorLoad switchNot recordedAlpha & Omega Semiconductor
  Printed CF01. Only the start matches what you typed, so this fits only if the rest of the marking is worn off.
  What it is
  Load switch
  Maker
  Alpha & Omega Semiconductor
  Package
  Not recorded
  Pins
  Not recorded
  Details
  USB Type-C protection 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 AOZ15333DI-01, opens in a new tab
- AOZ15333DI-02printed CF02Load switch, Alpha & Omega SemiconductorLoad switchNot recordedAlpha & Omega Semiconductor
  Printed CF02. Only the start matches what you typed, so this fits only if the rest of the marking is worn off.
  What it is
  Load switch
  Maker
  Alpha & Omega Semiconductor
  Package
  Not recorded
  Pins
  Not recorded
  Details
  USB Type-C protection 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 AOZ15333DI-02, opens in a new tab
- SMCG45Aprinted GFVTVS diode, VishayTVS diodeNot recordedVishay
  Printed GFV. 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
  1500 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 SMCG45A, opens in a new tab
- SMCG48Aprinted GFXTVS diode, VishayTVS diodeNot recordedVishay
  Printed GFX. 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
  1500 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 SMCG48A, opens in a new tab
- SMCG51Aprinted GFZTVS diode, VishayTVS diodeNot recordedVishay
  Printed GFZ. 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
  1500 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 SMCG51A, opens in a new tab
- SN74LVC1G14DRLprinted CF7Logic gate, 5 pins, Texas InstrumentsLogic gate5 pinsTexas Instruments
  Printed CF7. Only the start matches what you typed, so this fits only if the rest of the marking is worn off.
  What it is
  Logic gate
  Maker
  Texas Instruments
  Package
  Not recorded
  Pins
  5
  Details
  Single Schmitt-Trigger Inverter
  Source
  From the manufacturer's datasheet
  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.
  Datasheetfor SN74LVC1G14DRL, 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; 3 a month are free.

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?

BC818-25

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?

Codes that begin with 6F

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