SMD code S55
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.
11 parts are printed S55
Not sure which one you have?
Answer up to 4 quick questions and these 11 parts are ranked, with a meter test that settles it. It works on a dead part too.
SFM55SMCRectifier, 2 pins, Formosa MicrosemiRectifierSMC2 pinsFormosa Microsemi
- What it is
- Rectifier
- Maker
- Formosa Microsemi
- Package
- SMC
- Pins
- 2
- Details
- Rectifier diode
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Silicon diode.
SM550ASMASchottky diode, 2 pins, LRCSchottky diodeSMA2 pinsLRC
- What it is
- Schottky diode
- Maker
- LRC
- Package
- SMA
- Pins
- 2
- Details
- Schottky diode, VR 50 V, IF 5 A, VF Max 0.7 V
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Schottky diode.
SM550AFSMAFSchottky diode, 2 pins, LRCSchottky diodeSMAF2 pinsLRC
- What it is
- Schottky diode
- Maker
- LRC
- Package
- SMAF
- Pins
- 2
- Details
- Schottky diode, VR 50 V, IF 5 A, VF Max 0.7 V
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Schottky diode.
SM550BSMBSchottky diode, 2 pins, LRCSchottky diodeSMB2 pinsLRC
- What it is
- Schottky diode
- Maker
- LRC
- Package
- SMB
- Pins
- 2
- Details
- Schottky diode, VR 50 V, IF 5 A, VF Max 0.7 V
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Schottky diode.
SM550BFSMBFSchottky diode, 2 pins, LRCSchottky diodeSMBF2 pinsLRC
- What it is
- Schottky diode
- Maker
- LRC
- Package
- SMBF
- Pins
- 2
- Details
- Schottky diode, VR 50 V, IF 5 A, VF Max 0.7 V
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Schottky diode.
FJX4005RSOT-323Digital transistor (PNP, resistors built in), 3 pins, Fairchild SemiconductorDigital transistor (PNP, resistors built in)SOT-3233 pinsFairchild Semiconductor
- What it is
- Digital transistor (PNP, resistors built in)
- Maker
- Fairchild Semiconductor
- Package
- SOT-323
- Pins
- 3
- Details
- PNP transistor: Sw, 50V, 100mA, 200mW, R1/R2=4.7k/10k
- Source
- Published code list
Is it dead? The meter test is below: Digital transistor.
XC6371E551PSOT-89-5DC-DC converter, 5 pins, TorexDC-DC converterSOT-89-55 pinsTorex
- What it is
- DC-DC converter
- Maker
- Torex
- Package
- SOT-89-5
- Pins
- 5
- Details
- DC/DC voltage converter IC: PW M st-up, 100kHz, 5.5V±2.5%, 100mA, int. Vdd
- Source
- Published code list
Is it dead? The meter test is below: Integrated circuit.
XC9148C43CER-GUSP-6CDC-DC converter, 6 pins, TorexDC-DC converterUSP-6C6 pinsTorex
- What it is
- DC-DC converter
- Maker
- Torex
- Package
- USP-6C
- Pins
- 6
- Details
- DC/DC voltage converter IC: PWM/PFM st-up, 1.2MHz, 4.3V±2%, 1.4A, CrL, +CE
- Source
- Published code list
Is it dead? The meter test is below: Integrated circuit.
XC9148C43CPR-GSOT-89-5DC-DC converter, 5 pins, TorexDC-DC converterSOT-89-55 pinsTorex
- What it is
- DC-DC converter
- Maker
- Torex
- Package
- SOT-89-5
- Pins
- 5
- Details
- DC/DC voltage converter IC: PW M/PFM step-up, 1.2MHz, 4.3V±2%, 1.4A, CrL, +CE
- Source
- Published code list
Is it dead? The meter test is below: Integrated circuit.
2 more parts have no package on record
SS55Schottky diode, Taitron ComponentsSchottky diodeNot recordedNot recordedTaitron Components
- What it is
- Schottky diode
- Maker
- Taitron Components
- Package
- Not recorded
- Pins
- Not recorded
- Details
- Surface Mount Schottky Rectifiers
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Schottky diode.
SS5P5Schottky diode, VishaySchottky diodeNot recordedNot recordedVishay
- What it is
- Schottky diode
- Maker
- Vishay
- Package
- Not recorded
- Pins
- Not recorded
- Details
- Diode: SBR, 50V, 5A, Vf<0.69V(5A)
- Source
- Published code list
Is it dead? The meter test is below: Schottky 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.
Schottky diode
Diode range, part lifted or one leg off the pad. Red probe on the anode.
Working, it reads
About 0.15 to 0.45 V anode to cathode, roughly half a silicon diode, and open the other way.
Dead, it reads
- The same reading both ways round, near 0 V with a continuous beep or the same middling value: shorted.
- A reading the wrong way round as well: leaky.
- Open both ways: failed open.
- 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 large Schottky can read about 0.1 V forward and beep like a short, and leaks a little the wrong way when good, more when warm. It is shorted only if it reads the same both ways. Measure it cold, beside an identical cold one.
A dead part still carries its marking. A short or an open says it has failed, not that it is a different part.
Digital transistor
Ohms range, part lifted. The datasheet gives the built-in resistors: R1 in series with the base, R2 from base to emitter.
Working, it reads
Base to emitter reads about R1 plus R2 either way round, about 20 kΩ on a 10 k and 10 k part, give or take their wide tolerance. Collector to emitter reads open. A part with no R2 reads a junction behind R1 one way instead.
Dead, it reads
- Collector to emitter the same both ways, near 0 Ω with a continuous beep: shorted.
- From the base, open or far above R1 plus R2: R1 has failed. Static damage shows here most often.
- Base to emitter near 0 Ω: failed short.
- 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:
- The readings depend on the resistor values, so an identical part elsewhere on the board is the surest reference. Measure it the same way.
- Watch for:
- On the diode range a good part with 10 kΩ resistors reads open on every pair, so a good part looks dead there. Use the ohms range.
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.
Printed with a code easy to misread as S55
One character differs, and it is one that is easy to confuse under a lamp. Each code has a page of its own.
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