SMD code A1s
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 A1 was searched.
211 parts are printed A1s
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.
BL8555-31ARBSOT-23-55 pins, Shanghai BellingSOT-23-55 pinsShanghai Belling
- What it is
- LDO regulator
- Maker
- Shanghai Belling
- Package
- SOT-23-5
- Pins
- 5
- Details
- Linear voltage regulator IC: LDO, 3.1V±2%, 50mA, +CE
- Source
- Published code list
Is it dead? The meter test is below: Voltage regulator.
BL8555-31KQSOT-3535 pins, Shanghai BellingSOT-3535 pinsShanghai Belling
- What it is
- LDO regulator
- Maker
- Shanghai Belling
- Package
- SOT-353
- Pins
- 5
- Details
- Linear voltage regulator IC: LDO, 3.1V±2%, 50mA
- Source
- Published code list
Is it dead? The meter test is below: Voltage regulator.
BL8555-31KRASOT-23-55 pins, Shanghai BellingSOT-23-55 pinsShanghai Belling
- What it is
- LDO regulator
- Maker
- Shanghai Belling
- Package
- SOT-23-5
- Pins
- 5
- Details
- Linear voltage regulator IC: LDO, 3.1V±2%, 50mA
- Source
- Published code list
Is it dead? The meter test is below: Voltage regulator.
BL8555-31KRBSOT-23-55 pins, Shanghai BellingSOT-23-55 pinsShanghai Belling
- What it is
- LDO regulator
- Maker
- Shanghai Belling
- Package
- SOT-23-5
- Pins
- 5
- Details
- Linear voltage regulator IC: LDO, 3.1V±2%, 50mA
- Source
- Published code list
Is it dead? The meter test is below: Voltage regulator.
BL8555-41AQSOT-3535 pins, Shanghai BellingSOT-3535 pinsShanghai Belling
- What it is
- LDO regulator
- Maker
- Shanghai Belling
- Package
- SOT-353
- Pins
- 5
- Details
- Linear voltage regulator IC: LDO, 4.1V±2%, 50mA, +CE
- Source
- Published code list
Is it dead? The meter test is below: Voltage regulator.
BL8555-41ARASOT-23-55 pins, Shanghai BellingSOT-23-55 pinsShanghai Belling
- What it is
- LDO regulator
- Maker
- Shanghai Belling
- Package
- SOT-23-5
- Pins
- 5
- Details
- Linear voltage regulator IC: LDO, 4.1V±2%, 50mA, +CE
- Source
- Published code list
Is it dead? The meter test is below: Voltage regulator.
BL8555-41ARBSOT-23-55 pins, Shanghai BellingSOT-23-55 pinsShanghai Belling
- What it is
- LDO regulator
- Maker
- Shanghai Belling
- Package
- SOT-23-5
- Pins
- 5
- Details
- Linear voltage regulator IC: LDO, 4.1V±2%, 50mA, +CE
- Source
- Published code list
Is it dead? The meter test is below: Voltage regulator.
BL8555-41KQSOT-3535 pins, Shanghai BellingSOT-3535 pinsShanghai Belling
- What it is
- LDO regulator
- Maker
- Shanghai Belling
- Package
- SOT-353
- Pins
- 5
- Details
- Linear voltage regulator IC: LDO, 4.1V±2%, 50mA
- Source
- Published code list
Is it dead? The meter test is below: Voltage regulator.
BL8555-41KRASOT-23-55 pins, Shanghai BellingSOT-23-55 pinsShanghai Belling
- What it is
- LDO regulator
- Maker
- Shanghai Belling
- Package
- SOT-23-5
- Pins
- 5
- Details
- Linear voltage regulator IC: LDO, 4.1V±2%, 50mA
- Source
- Published code list
Is it dead? The meter test is below: Voltage regulator.
BL8555-41KRBSOT-23-55 pins, Shanghai BellingSOT-23-55 pinsShanghai Belling
- What it is
- LDO regulator
- Maker
- Shanghai Belling
- Package
- SOT-23-5
- Pins
- 5
- Details
- Linear voltage regulator IC: LDO, 4.1V±2%, 50mA
- Source
- Published code list
Is it dead? The meter test is below: Voltage regulator.
BZX884-B2V4SOD-8822 pins, NXPSOD-8822 pinsNXP
- What it is
- Not recorded
- Maker
- NXP
- Package
- SOD-882
- Pins
- 2
- Details
- Z-diode: 2.4V±2%, 250mW
- Source
- Published code list
Is it dead? The meter test is below: Silicon diode.
CDSOT23-SLVU2.8SOT-233 pins, BournsSOT-233 pinsBourns
- What it is
- Not recorded
- Maker
- Bourns
- Package
- SOT-23
- Pins
- 3
- Details
- TVS Diode
- Source
- Published code list
Is it dead? The meter test is below: TVS or ESD protection diode.
CHP202KPTSOT-233 pins, Chenmko EnterpriseSOT-233 pinsChenmko Enterprise
- What it is
- Not recorded
- Maker
- Chenmko Enterprise
- Package
- SOT-23
- Pins
- 3
- Details
- Diode: Dual, Sw, 80V, 100mA, Vf<1.2V(100mA), 4ns
- Source
- Published code list
Is it dead? The meter test is below: Silicon diode.
2 more parts have no package on record
CFY104 pins, InfineonNot recorded4 pinsInfineon
- What it is
- Not recorded
- Maker
- Infineon
- Package
- Not recorded
- Pins
- 4
- Source
- Published code list
Is it dead? The meter test is below: This part.
CFY19-184 pins, InfineonNot recorded4 pinsInfineon
- What it is
- Not recorded
- Maker
- Infineon
- Package
- Not recorded
- Pins
- 4
- 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.
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.
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.
TVS or ESD protection diode
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
- , 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.
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.
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