SMD code 54-
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.
92 parts are printed 54-
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.
DTA114YUBSOT-323Digital transistor (PNP, resistors built in), 3 pins, ROHMDigital transistor (PNP, resistors built in)SOT-3233 pinsROHM
- What it is
- Digital transistor (PNP, resistors built in)
- Maker
- ROHM
- Package
- SOT-323
- Pins
- 3
- Details
- PNP digital transistor (bias resistor built-in); R1 = 10kOhm, R2 = 47kOhm
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Digital transistor.
LMBR0540FT1GSOD-123FSchottky diode, 2 pins, LRCSchottky diodeSOD-123F2 pinsLRC
- What it is
- Schottky diode
- Maker
- LRC
- Package
- SOD-123F
- Pins
- 2
- Details
- Schottky diode, VR 40 V, IF 0.5 A, VF Max 0.55 V
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Schottky diode.
MM5Z3V6-CSOD-523Zener diode, 2 pins, SeCoSZener diodeSOD-5232 pinsSeCoS
- What it is
- Zener diode
- Maker
- SeCoS
- Package
- SOD-523
- Pins
- 2
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Zener diode.
MT5Z3V6-CSOD-523Zener diode, 2 pins, SeCoSZener diodeSOD-5232 pinsSeCoS
- What it is
- Zener diode
- Maker
- SeCoS
- Package
- SOD-523
- Pins
- 2
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Zener diode.
P4SOD54ASOD-123TVS diode, 2 pins, WeEn SemiconductorsTVS diodeSOD-1232 pinsWeEn Semiconductors
- What it is
- TVS diode
- Maker
- WeEn Semiconductors
- Package
- SOD-123
- Pins
- 2
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: TVS or ESD protection diode.
PDTC143ZUSOT-323Digital transistor (NPN, resistors built in), 3 pins, NexperiaDigital transistor (NPN, resistors built in)SOT-3233 pinsNexperia
- What it is
- Digital transistor (NPN, resistors built in)
- Maker
- Nexperia
- Package
- SOT-323
- Pins
- 3
- Details
- 50 V, 100 mA NPN resistor-equipped transistor; R1 = 4.7 kΩ, R2 = 47 kΩ
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Digital transistor.
RB541SM-40SOD-523Schottky diode, 2 pins, ROHMSchottky diodeSOD-5232 pinsROHM
- What it is
- Schottky diode
- Maker
- ROHM
- Package
- SOD-523
- Pins
- 2
- Details
- Schottky Barrier Diode
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Schottky diode.
RSX201LAM30SOD-128Schottky diode, 2 pins, ROHMSchottky diodeSOD-1282 pinsROHM
- What it is
- Schottky diode
- Maker
- ROHM
- Package
- SOD-128
- Pins
- 2
- Details
- Schottky Barrier Diode
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Schottky diode.
RSX201LAM30TFSOD-128Schottky diode, 2 pins, ROHMSchottky diodeSOD-1282 pinsROHM
- What it is
- Schottky diode
- Maker
- ROHM
- Package
- SOD-128
- Pins
- 2
- Details
- Schottky Barrier Diode
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Schottky diode.
6 more parts have no package on record
ET554ADJY1BLDO regulator, ETEKLDO regulatorNot recordedNot recordedETEK
- What it is
- LDO regulator
- Maker
- ETEK
- Package
- Not recorded
- Pins
- Not recorded
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Voltage regulator.
LMBR0540ET1GSchottky diode, LRCSchottky diodeNot recordedNot recordedLRC
- What it is
- Schottky diode
- Maker
- LRC
- Package
- Not recorded
- Pins
- Not recorded
- Details
- Schottky diode, VR 40 V, IF 0.5 A, VF Max 0.55 V
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Schottky diode.
RSX201L-30Schottky diode, ROHMSchottky diodeNot recordedNot recordedROHM
- What it is
- Schottky diode
- Maker
- ROHM
- Package
- Not recorded
- Pins
- Not recorded
- Details
- Schottky Barrier Diode
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Schottky diode.
RSX201L-30DDSchottky diode, ROHMSchottky diodeNot recordedNot recordedROHM
- What it is
- Schottky diode
- Maker
- ROHM
- Package
- Not recorded
- Pins
- Not recorded
- Details
- Schottky Barrier Diode
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Schottky diode.
S-LMBR0540ET1GSchottky diode, LRCSchottky diodeNot recordedNot recordedLRC
- What it is
- Schottky diode
- Maker
- LRC
- Package
- Not recorded
- Pins
- Not recorded
- Details
- Schottky diode, VR 40 V, IF 0.5 A, VF Max 0.55 V
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Schottky diode.
SAV-541+RF amplifier (MMIC), Mini-CircuitsRF amplifier (MMIC)Not recordedNot recordedMini-Circuits
- What it is
- RF amplifier (MMIC)
- Maker
- Mini-Circuits
- Package
- Not recorded
- Pins
- Not recorded
- Details
- MMIC amplifier, 0.045-6 GHz
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: RF amplifier.
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.
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.
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.
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.
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.
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.
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.
RF amplifier
Voltage, board powered, on the output pin that the bias resistor or choke feeds.
Working, it reads
The output pin sits at the device voltage the datasheet gives, a few volts, below the supply.
Dead, it reads
- Output pin at 0 V, or near 0 Ω to ground with the power off: shorted inside.
- Output pin at the full supply voltage: open inside, no current flowing.
- On the board:
- Measured on the board with power on; the bias network is part of the reading.
- 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 figures depend on the part and its bias resistor. The datasheet gives both.
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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