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.
CGRTS4001-HFSOD-123FRectifier, 2 pins, ComchipRectifierSOD-123F2 pinsComchip
- What it is
- Rectifier
- Maker
- Comchip
- Package
- SOD-123F
- Pins
- 2
- Details
- 50 V, 1 A rectifier
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Silicon diode.
CHP202KGPSOT-23Switching diode, 3 pins, ChenmkoSwitching diodeSOT-233 pinsChenmko
- What it is
- Switching diode
- Maker
- Chenmko
- Package
- SOT-23
- Pins
- 3
- Details
- SWITCHING DIODE, 80 V, 0.1 A
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Silicon diode.
CHP222GPSOT-416Switching diode, 3 pins, ChenmkoSwitching diodeSOT-4163 pinsChenmko
- What it is
- Switching diode
- Maker
- Chenmko
- Package
- SOT-416
- Pins
- 3
- Details
- SWITCHING DIODE, 80 V, 0.1 A
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Silicon diode.
CMSP3401T-P2-HFSOT-23P-channel MOSFET, 3 pins, ComchipP-channel MOSFETSOT-233 pinsComchip
- What it is
- P-channel MOSFET
- Maker
- Comchip
- Package
- SOT-23
- Pins
- 3
- Details
- -30 V, -4.2 A P-channel MOSFET
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: P-channel MOSFET.
DSR1ASOD-123FRectifier, 2 pins, YFWRectifierSOD-123F2 pinsYFW
- What it is
- Rectifier
- Maker
- YFW
- Package
- SOD-123F
- Pins
- 2
- Details
- Rectifier diode
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Silicon diode.
FM4001SMARectifier, 2 pins, Formosa MicrosemiRectifierSMA2 pinsFormosa Microsemi
- What it is
- Rectifier
- Maker
- Formosa Microsemi
- Package
- SMA
- Pins
- 2
- Details
- Rectifier diode
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Silicon diode.
FM4001-MSOD-123Rectifier, 2 pins, Formosa MicrosemiRectifierSOD-1232 pinsFormosa Microsemi
- What it is
- Rectifier
- Maker
- Formosa Microsemi
- Package
- SOD-123
- Pins
- 2
- Details
- Rectifier diode
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Silicon diode.
FM4001-M-Q1SOD-123Rectifier, 2 pins, Formosa MicrosemiRectifierSOD-1232 pinsFormosa Microsemi
- What it is
- Rectifier
- Maker
- Formosa Microsemi
- Package
- SOD-123
- Pins
- 2
- Details
- Rectifier diode
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Silicon diode.
7 more parts have no package on record
ESDALC6V1P5TVS diode, STMicroelectronicsTVS diodeNot recordedNot recordedSTMicroelectronics
- What it is
- TVS diode
- Maker
- STMicroelectronics
- Package
- Not recorded
- Pins
- Not recorded
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: TVS or ESD protection diode.
FM4001-LRectifier, Formosa MicrosemiRectifierNot recordedNot recordedFormosa Microsemi
- What it is
- Rectifier
- Maker
- Formosa Microsemi
- Package
- Not recorded
- Pins
- Not recorded
- Details
- Rectifier diode
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Silicon diode.
FM4001-L-Q1Rectifier, Formosa MicrosemiRectifierNot recordedNot recordedFormosa Microsemi
- What it is
- Rectifier
- Maker
- Formosa Microsemi
- Package
- Not recorded
- Pins
- Not recorded
- Details
- Rectifier diode
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Silicon diode.
FM4001-MHRectifier, Formosa MicrosemiRectifierNot recordedNot recordedFormosa Microsemi
- What it is
- Rectifier
- Maker
- Formosa Microsemi
- Package
- Not recorded
- Pins
- Not recorded
- Details
- Rectifier diode
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Silicon diode.
FM4001-MH-Q1Rectifier, Formosa MicrosemiRectifierNot recordedNot recordedFormosa Microsemi
- What it is
- Rectifier
- Maker
- Formosa Microsemi
- Package
- Not recorded
- Pins
- Not recorded
- Details
- Rectifier diode
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Silicon diode.
FM4001-MSRectifier, Formosa MicrosemiRectifierNot recordedNot recordedFormosa Microsemi
- What it is
- Rectifier
- Maker
- Formosa Microsemi
- Package
- Not recorded
- Pins
- Not recorded
- Details
- Rectifier diode
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Silicon diode.
FM4001-MS-Q1Rectifier, Formosa MicrosemiRectifierNot recordedNot recordedFormosa Microsemi
- What it is
- Rectifier
- Maker
- Formosa Microsemi
- Package
- Not recorded
- Pins
- Not recorded
- Details
- Rectifier diode
- Source
- Manufacturer 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.
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.
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.
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.
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