SMD code A4 in DFN
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 DFN are printed A4
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.
LD39020ADTPU11RDFNSGS-Thomson MicroelectronicsNot recordedSGS-Thomson Microelectronics
- What it is
- Not recorded
- Maker
- SGS-Thomson Microelectronics
- Package
- DFN
- Pins
- Not recorded
- Details
- equivalent [1.1V LDO]
- Source
- Published code list
Is it dead? The meter test is below: Voltage regulator.
R3118K101ADFNVoltage supervisor, RicohVoltage supervisorRicoh
- What it is
- Voltage supervisor
- Maker
- Ricoh
- Package
- DFN
- Pins
- Not recorded
- Details
- Voltage detector IC: 1.0V±22.5mV, -Reset ODO, Sense
- Source
- Published code list
Is it dead? The meter test is below: Integrated circuit.
RT9011-KMPQVDFNRichtekNot recordedRichtek
- What it is
- Not recorded
- Maker
- Richtek
- Package
- DFN
- Pins
- Not recorded
- Details
- Voltage regulator
- Source
- Published code list
Is it dead? The meter test is below: Voltage regulator.
UM15315DADFNLDO regulator, Union SemiconductorLDO regulatorUnion Semiconductor
- What it is
- LDO regulator
- Maker
- Union Semiconductor
- Package
- DFN
- Pins
- Not recorded
- Details
- Linear voltage regulator IC: LDO, 1.5V±2%, 100mA
- Source
- Published code list
Is it dead? The meter test is below: Voltage regulator.
11 more parts have no package on record. Nothing rules them out, so they stay.
BZX884B3V3Zener diode, Good-ArkZener diodeGood-Ark
- What it is
- Zener diode
- Maker
- Good-Ark
- Package
- Not recorded
- Pins
- Not recorded
- Details
- Zener diode, VZ 3.3 V, 0.25 W
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Zener diode.
EMA4Digital transistor (resistors built in), ROHMDigital transistor (resistors built in)ROHM
- What it is
- Digital transistor (resistors built in)
- Maker
- ROHM
- Package
- Not recorded
- Pins
- Not recorded
- Details
- Emitter common(dual digital transistor)
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Digital transistor.
FM4004-LRectifier, Formosa MicrosemiRectifierFormosa 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.
FM4004-L-Q1Rectifier, Formosa MicrosemiRectifierFormosa 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.
FM4004-MHRectifier, Formosa MicrosemiRectifierFormosa 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.
FM4004-MH-Q1Rectifier, Formosa MicrosemiRectifierFormosa 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.
FM4004-MSRectifier, Formosa MicrosemiRectifierFormosa 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.
FM4004-MS-Q1Rectifier, Formosa MicrosemiRectifierFormosa 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.
FM4004-MSTRectifier, Formosa MicrosemiRectifierFormosa 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.
FM4004-MST-Q1Rectifier, Formosa MicrosemiRectifierFormosa 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.
FM4004-SFRectifier, Formosa MicrosemiRectifierFormosa 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.
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.
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.
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.
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.
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.
Codes that begin with A4
For a marking with its end worn or burnt off. Each code has a page of its own.
- A422
- A4886D1
- A4988AD1
- A4988BD1
- A4988CD1
- A4988DD1
- A4988ED1
- A4990D3
- A4991D1
- A4992D1
- A48901
- A49951
- A413
- A433
- A474
- A49921
- A49961
- A401
- A441
- A452
- A462
- A482
- A492
- A4C1
- A4F2
- A47A2
- A4X1
- A40A2
- A40B2
- A41A1
- A41B1
- A42A1
- A42B1
- A43A1
- A43B1
- A44A1
- A44B1
- A45A1
- A45B1
- A46A1
- A46B1
Codes not listed here are printed on 45 more parts.
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