SMD code A1
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.
12 parts are printed A1
Not sure which one you have?
Answer up to 4 quick questions and these 12 parts are ranked, with a meter test that settles it. It works on a dead part too.
AO3401SOT-23P-channel MOSFET, 3 pins, Alpha & Omega SemiconductorP-channel MOSFETSOT-233 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? The meter test is below: P-channel MOSFET.
AO3401LSOT-23P-channel MOSFET, 3 pins, Alpha & Omega SemiconductorP-channel MOSFETSOT-233 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? The meter test is below: P-channel MOSFET.
BAS16HSOD-123FSwitching diode, 2 pins, NexperiaSwitching diodeSOD-123F2 pinsNexperia
- What it is
- Switching diode
- Maker
- Nexperia
- Package
- SOD-123F
- Pins
- 2
- Pinout
- 1 cathode
- 2 anode
- Details
- High-speed switching diode, single
- Source
- From the manufacturer's datasheet
Is it dead? The meter test is below: Silicon diode.
BAW56SOT-23Switching diode, 3 pins, DiotecSwitching diodeSOT-233 pinsDiotec
- What it is
- Switching diode
- Maker
- Diotec
- Package
- SOT-23
- Pins
- 3
- Details
- SMD Small Signal Diodes
- Source
- From the manufacturer's datasheet
Is it dead? The meter test is below: Silicon diode.
BAW56HSOT-23Switching diode, 3 pins, Taiwan SemiconductorSwitching diodeSOT-233 pinsTaiwan Semiconductor
- What it is
- Switching diode
- Maker
- Taiwan Semiconductor
- Package
- SOT-23
- Pins
- 3
- Source
- From the manufacturer's datasheet
Is it dead? The meter test is below: Silicon diode.
BAW56SSOT-363Switching diode, 6 pins, NexperiaSwitching diodeSOT-3636 pinsNexperia
- What it is
- Switching diode
- Maker
- Nexperia
- Package
- SOT-363
- Pins
- 6
- Details
- High-speed switching diode
- Source
- From the manufacturer's datasheet
Is it dead? The meter test is below: Silicon diode.
BAW56WSOT-323Switching diode, 3 pins, NexperiaSwitching diodeSOT-3233 pinsNexperia
- What it is
- Switching diode
- Maker
- Nexperia
- Package
- SOT-323
- Pins
- 3
- Details
- SMD Small Signal Diodes
- Source
- From the manufacturer's datasheet
Is it dead? The meter test is below: Silicon diode.
BZX84-C75SOT-23Zener diode, 3 pins, NexperiaZener diodeSOT-233 pinsNexperia
- What it is
- Zener diode
- Maker
- Nexperia
- Package
- SOT-23
- Pins
- 3
- Pinout
- 1 anode
- 2 not connected
- 3 cathode
- Details
- 75 V approx. ±5% voltage regulator (Zener) diode
- Source
- From the manufacturer's datasheet
Is it dead? The meter test is below: Zener diode.
MMBD4148CASOT-23Switching diode, 3 pins, Taiwan SemiconductorSwitching diodeSOT-233 pinsTaiwan Semiconductor
- What it is
- Switching diode
- Maker
- Taiwan Semiconductor
- Package
- SOT-23
- Pins
- 3
- Source
- From the manufacturer's datasheet
Is it dead? The meter test is below: Silicon diode.
TLV713185PDQNX2SONLDO regulator, 4 pins, Texas InstrumentsLDO regulatorX2SON4 pinsTexas Instruments
- What it is
- LDO regulator
- Maker
- Texas Instruments
- Package
- X2SON
- Pins
- 4
- Details
- Capacitor-Free, 150-mA, Low-Dropout Regulator With Foldback Current Limit for Portable Devices
- Source
- From the manufacturer's datasheet
Is it dead? The meter test is below: Voltage regulator.
2 more parts have no package on record
BAV222Switching diode, InfineonSwitching diodeNot recordedNot recordedInfineon
- What it is
- Switching diode
- Maker
- Infineon
- Package
- Not recorded
- Pins
- Not recorded
- Source
- From the manufacturer's datasheet
Is it dead? The meter test is below: Silicon diode.
BAW222Diode, InfineonDiodeNot recordedNot recordedInfineon
- What it is
- Diode
- Maker
- Infineon
- Package
- Not recorded
- Pins
- Not recorded
- Source
- From the manufacturer's datasheet
Is it dead? The meter test is below: Silicon diode.
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.
P-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 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
- 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.
Silicon diode
Diode range, part lifted or one leg off the pad. Red probe on the anode.
Working, it reads
About 0.5 to 0.8 V anode to cathode, and open the other way. Small switching diodes read about 0.6 to 0.7 V; large rectifiers can read a little lower.
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: failed open.
- A reading the wrong way round as well: 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 three-pin body can hold two diodes. With a common pin they read two junctions from that pin, just like a transistor; in series they read two drops end to end. Test each pair the datasheet names.
A dead part still carries its marking. A short or an open says it has failed, not that it is a different part.
Zener diode
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.
Voltage regulator
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.
Printed with a code easy to misread as A1
One character differs, and it is one that is easy to confuse under a lamp. Each code has a page of its own.
Codes that begin with A1
For a marking with its end worn or burnt off. Each code has a page of its own.
Codes not listed here are printed on 57 more parts.
Open this in the search to correct a character or try another package.