SMD code ATs in 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 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 AT was searched.

16 parts in SOT-23 are printed ATs

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.

all SOT-23, 3 pins. What differs:

AO3424SOT-23MOSFET, Alpha & Omega SemiconductorMOSFETAlpha & Omega Semiconductor
What it is
MOSFET
Maker
Alpha & Omega Semiconductor
Package
SOT-23
Pins
3
Details
Low-voltage (12-30 V) MOSFET
Source
Manufacturer datasheet
Is it dead? The meter test is below: MOSFET.
Datasheetfor AO3424, opens in a new tab
AO3424LSOT-23MOSFET, Alpha & Omega SemiconductorMOSFETAlpha & Omega Semiconductor
What it is
MOSFET
Maker
Alpha & Omega Semiconductor
Package
SOT-23
Pins
3
Details
Low-voltage (12-30 V) MOSFET
Source
Manufacturer datasheet
Is it dead? The meter test is below: MOSFET.
Datasheetfor AO3424L, opens in a new tab
CHT170GPSOT-23N-channel MOSFET, ChenmkoN-channel MOSFETChenmko
What it is
N-channel MOSFET
Maker
Chenmko
Package
SOT-23
Pins
3
Details
N-Channel Enhancement Mode Field Effect Transistor, 60 V, 0.5 A
Source
Manufacturer datasheet
Is it dead? The meter test is below: N-channel MOSFET.
Datasheetfor CHT170GP, opens in a new tab
2SC4066SOT-23NPN transistor, Sanyo ElectricNPN transistorSanyo Electric
What it is
NPN transistor
Maker
Sanyo Electric
Package
SOT-23
Pins
3
Details
NPN transistor: AF, GP, 50V, 100mA, 200mW, B>80, 250MHz
Source
Published code list
Is it dead? The meter test is below: NPN transistor.
2SC4326K-SSOT-23NPN transistor, ROHMNPN transistorROHM
What it is
NPN transistor
Maker
ROHM
Package
SOT-23
Pins
3
Details
Si-npn: HF, 12V, 50mA, 150mW, B=270..560, >800MHz
Source
Published code list
Is it dead? The meter test is below: NPN transistor.
ADM810TARTSOT-23Voltage supervisor, Analog DevicesVoltage supervisorAnalog Devices
What it is
Voltage supervisor
Maker
Analog Devices
Package
SOT-23
Pins
3
Details
Voltage detector IC: 3.08V±1.5%, +Reset PPO
Source
Published code list
Is it dead? The meter test is below: Integrated circuit.
AME8500AEETAE46SOT-23Voltage supervisor, AMEVoltage supervisorAME
What it is
Voltage supervisor
Maker
AME
Package
SOT-23
Pins
3
Details
CMOS-IC: Voltage Detector 4.63V, -Reset Push-pull output, 150ms
Source
Published code list
Is it dead? The meter test is below: Integrated circuit.
AME8500AEETAE46ZSOT-23Voltage supervisor, AMEVoltage supervisorAME
What it is
Voltage supervisor
Maker
AME
Package
SOT-23
Pins
3
Details
CMOS-IC: Voltage Detector 4.63V, -Reset Push-pull output, 150ms
Source
Published code list
Is it dead? The meter test is below: Integrated circuit.
AME8501AEETAE46SOT-23AMENot recordedAME
What it is
Not recorded
Maker
AME
Package
SOT-23
Pins
3
Details
CMOS-IC: Voltage Detector 4.63V, -Reset Push-pull output, 150ms
Source
Published code list
Is it dead? The meter test is below: Integrated circuit.
BAT18-06SOT-23SiemensNot recordedSiemens
What it is
Not recorded
Maker
Siemens
Package
SOT-23
Pins
3
Details
dual ca BAT18 RF pin
Source
Published code list
Is it dead? The meter test is below: This part.
BCW60ERSOT-23InfineonNot recordedInfineon
What it is
Not recorded
Maker
Infineon
Package
SOT-23
Pins
3
Source
Published code list
Is it dead? The meter test is below: This part.
GS6333UR20D2SOT-23Voltage supervisor, VishayVoltage supervisorVishay
What it is
Voltage supervisor
Maker
Vishay
Package
SOT-23
Pins
3
Details
CMOS-IC: Voltage Detector 2V, -Reset Push-pull output, 30ms
Source
Published code list
Is it dead? The meter test is below: Integrated circuit.
MIC803-46D3VM3SOT-23MicrelNot recordedMicrel
What it is
Not recorded
Maker
Micrel
Package
SOT-23
Pins
3
Details
Microprocessor reset circuit
Source
Published code list
Is it dead? The meter test is below: This part.
SiP6333R20D2SOT-23Voltage supervisor, VishayVoltage supervisorVishay
What it is
Voltage supervisor
Maker
Vishay
Package
SOT-23
Pins
3
Details
CMOS-IC: Voltage Detector 2V, Reset Push-pull output 30ms
Source
Published code list
Is it dead? The meter test is below: Integrated circuit.
V6309SSP3BSOT-23EM Microelectronic-Marin SANot recordedEM Microelectronic-Marin SA
What it is
Not recorded
Maker
EM Microelectronic-Marin SA
Package
SOT-23
Pins
3
Details
Microprocessor reset circuit
Source
Published code list
Is it dead? The meter test is below: This part.

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.

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.

N-channel MOSFET

Diode range, part lifted. Test drain to source first, then short gate to source and test again.

Working, it reads

Red probe on the source, black on the drain: 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: the gate usually has a resistor to the source, so gate to source reads that resistor, which is not a fault. A drain short can be the load. 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.

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.

Integrated circuit

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.

This part

Diode range and ohms range, part lifted.

Working, it reads

Depends on what it is. The datasheet, or an identical part, says.

Dead, it reads

Between two pins, the same reading both ways, near 0 V with a continuous beep: shorted.
Open between every pair of pins: failed open, or a part that reads open when working.

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.

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 ATs

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 7 more parts.

Did you find your part?

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