SMD code 55 in SOT-23-5
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.
4 parts in SOT-23-5 are printed 55
Not sure which one you have?
Answer up to 4 quick questions and these 43 parts are ranked, with a meter test that settles it. It works on a dead part too.
15 parts have no package on record. Nothing rules them out, so they stay.
74AUP1Z125GNNXPNot recordedNot recordedNXP
- What it is
- Not recorded
- Maker
- NXP
- Package
- Not recorded
- Pins
- Not recorded
- Details
- CMOS logic IC: X-tal driver with enable and internal resistor
- Source
- Published code list
Is it dead? The meter test is below: Resistor.
74AUP1Z125GSNXPNot recordedNot recordedNXP
- What it is
- Not recorded
- Maker
- NXP
- Package
- Not recorded
- Pins
- Not recorded
- Details
- CMOS logic IC: X-tal driver with enable and internal resistor
- Source
- Published code list
Is it dead? The meter test is below: Resistor.
AP8822N-25GIVoltage supervisor, Anwell SemiconductorVoltage supervisorNot recordedAnwell Semiconductor
- What it is
- Voltage supervisor
- Maker
- Anwell Semiconductor
- Package
- Not recorded
- Pins
- Not recorded
- Details
- Voltage detector IC: 2.5V±2%, -Reset ODO, 200ms Rt delay, H-free
- Source
- Published code list
Is it dead? The meter test is below: Integrated circuit.
AP8822N-25GSVoltage supervisor, Anwell SemiconductorVoltage supervisorNot recordedAnwell Semiconductor
- What it is
- Voltage supervisor
- Maker
- Anwell Semiconductor
- Package
- Not recorded
- Pins
- Not recorded
- Details
- Voltage detector IC: 2.5V±2%, -Reset ODO, 200ms Rt delay, H-free
- Source
- Published code list
Is it dead? The meter test is below: Integrated circuit.
AP8822N-25PIVoltage supervisor, Anwell SemiconductorVoltage supervisorNot recordedAnwell Semiconductor
- What it is
- Voltage supervisor
- Maker
- Anwell Semiconductor
- Package
- Not recorded
- Pins
- Not recorded
- Details
- Voltage detector IC: 2.5V±2%, -Reset ODO, 200ms Rt delay
- Source
- Published code list
Is it dead? The meter test is below: Integrated circuit.
AP8822N-25PSVoltage supervisor, Anwell SemiconductorVoltage supervisorNot recordedAnwell Semiconductor
- What it is
- Voltage supervisor
- Maker
- Anwell Semiconductor
- Package
- Not recorded
- Pins
- Not recorded
- Details
- Voltage detector IC: 2.5V±2%, -Reset ODO, 200ms Rt delay
- Source
- Published code list
Is it dead? The meter test is below: Integrated circuit.
BAT15-055R4 pins, InfineonNot recorded4 pinsInfineon
- What it is
- Not recorded
- Maker
- Infineon
- Package
- Not recorded
- Pins
- 4
- Details
- 8GHz schottky ring quad
- Source
- Published code list
Is it dead? The meter test is below: Schottky diode.
BAT15-055S2 pins, InfineonNot recorded2 pinsInfineon
- What it is
- Not recorded
- Maker
- Infineon
- Package
- Not recorded
- Pins
- 2
- Details
- 8GHz schottky diode
- Source
- Published code list
Is it dead? The meter test is below: Schottky diode.
BBY57-02WInfineonNot recordedNot recordedInfineon
- What it is
- Not recorded
- Maker
- Infineon
- Package
- Not recorded
- Pins
- Not recorded
- Details
- C-diode: Dual, Tuning, VCO, 10V, 4..5,5/16,5..18,6pF(4/1V)
- Source
- Published code list
Is it dead? The meter test is below: Silicon diode.
CDZ5.1BZener diode, ROHMZener diodeNot recordedROHM
- What it is
- Zener diode
- Maker
- ROHM
- Package
- Not recorded
- Pins
- Not recorded
- Details
- Z-diode: 5,1V±2,5%, 40mA, 1W
- Source
- Published code list
Is it dead? The meter test is below: Zener diode.
EC95810N25C7IVoltage supervisor, E-CMOSVoltage supervisorNot recordedE-CMOS
- What it is
- Voltage supervisor
- Maker
- E-CMOS
- Package
- Not recorded
- Pins
- Not recorded
- Details
- Voltage detector IC: 2.5V±2%, -Reset ODO, Td=200ms
- Source
- Published code list
Is it dead? The meter test is below: Integrated circuit.
EC95810N25C7SVoltage supervisor, E-CMOSVoltage supervisorNot recordedE-CMOS
- What it is
- Voltage supervisor
- Maker
- E-CMOS
- Package
- Not recorded
- Pins
- Not recorded
- Details
- Voltage detector IC: 2.5V±2%, -Reset ODO, Td=200ms
- Source
- Published code list
Is it dead? The meter test is below: Integrated circuit.
FSD273TAZetexNot recordedNot recordedZetex
- What it is
- Not recorded
- Maker
- Zetex
- Package
- Not recorded
- Pins
- Not recorded
- Details
- Varicaps
- Source
- Published code list
Is it dead? The meter test is below: PIN diode or varicap.
IXD5126C31A7R-GVoltage supervisor, IXYSVoltage supervisorNot recordedIXYS
- What it is
- Voltage supervisor
- Maker
- IXYS
- Package
- Not recorded
- Pins
- Not recorded
- Details
- Voltage detector IC: 3.1V±0.8%, -Reset PPO
- Source
- Published code list
Is it dead? The meter test is below: Integrated circuit.
LM4855IBLNational SemiconductorNot recordedNot recordedNational Semiconductor
- What it is
- Not recorded
- Maker
- National Semiconductor
- Package
- Not recorded
- Pins
- Not recorded
- Details
- Linear IC: APA, BTL, 2.7..5.5V, 1.1W(8)+2x115mW(32), SPI
- Source
- Published code list
Is it dead? The meter test is below: Integrated circuit.
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.
Resistor
Ohms range, across it, power off.
Working, it reads
Its marked value, within tolerance. On the board it reads the same or lower, because everything around it sits in parallel.
Dead, it reads
- Open: burnt, cracked, or eaten through by sulphur. The commonest failure.
- Well above its marked value: drifted high.
- On the board, clearly higher than its marked value: it has failed, since the board can only pull a reading down.
- On the board:
- A reading lower than marked on the board proves nothing; lift one end. A reading higher than marked is a fault even on the board.
- Compare:
- The same position on another channel usually carries the same value, and so does the matching part on another board.
- Watch for:
- A burnt resistor usually means the part it feeds pulled too much. Find that before fitting a new one, or it burns too. The marking, not the reading, says what to fit.
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.
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.
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.
PIN diode or varicap
Diode range, part lifted or one leg off the pad. Red probe on the anode.
Working, it reads
About 0.6 to 0.9 V anode to cathode, 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.
- 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 varicap that has drifted in capacitance reads normal on a meter. Only a capacitance meter or the tuning itself shows it.
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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