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.
15 parts have no package on record. Nothing rules them out, so they stay.
FM4004-SF-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.
HFCN-4400+RF filter, Mini-CircuitsRF filterMini-Circuits
- What it is
- RF filter
- Maker
- Mini-Circuits
- Package
- Not recorded
- Pins
- Not recorded
- Details
- LTCC filter, 5000-10100 MHz
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: This part.
HFCN-4400D+RF filter, Mini-CircuitsRF filterMini-Circuits
- What it is
- RF filter
- Maker
- Mini-Circuits
- Package
- Not recorded
- Pins
- Not recorded
- Details
- LTCC filter, 5000-10100 MHz
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: This part.
KDZ36EVZener diode, KECZener diodeKEC
- What it is
- Zener diode
- Maker
- KEC
- Package
- Not recorded
- Pins
- Not recorded
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Zener diode.
LBAV70TT1GSwitching diode, LRCSwitching diodeLRC
- What it is
- Switching diode
- Maker
- LRC
- Package
- Not recorded
- Pins
- Not recorded
- Details
- Switching diode, VR 70 V, IF 200 mA, VF Max 1.25 V
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Silicon diode.
S-LBAV70TT1GSwitching diode, LRCSwitching diodeLRC
- What it is
- Switching diode
- Maker
- LRC
- Package
- Not recorded
- Pins
- Not recorded
- Details
- Switching diode, VR 70 V, IF 200 mA, VF Max 1.25 V
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Silicon diode.
SM4004JD-CRectifier, SeCoSRectifierSeCoS
- What it is
- Rectifier
- Maker
- SeCoS
- Package
- Not recorded
- Pins
- Not recorded
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Silicon diode.
SM4004MRectifier, SeCoSRectifierSeCoS
- What it is
- Rectifier
- Maker
- SeCoS
- Package
- Not recorded
- Pins
- Not recorded
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Silicon diode.
TSCD14WSchottky diode, Taitron ComponentsSchottky diodeTaitron Components
- What it is
- Schottky diode
- Maker
- Taitron Components
- Package
- Not recorded
- Pins
- Not recorded
- Details
- Low Profile Chip Type Schottky Rectifier
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Schottky diode.
TSCD14WSSchottky diode, Taitron ComponentsSchottky diodeTaitron Components
- What it is
- Schottky diode
- Maker
- Taitron Components
- Package
- Not recorded
- Pins
- Not recorded
- Details
- Low Profile Chip Type Schottky Rectifier
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Schottky diode.
1SS383ToshibaNot recordedToshiba
- What it is
- Not recorded
- Maker
- Toshiba
- Package
- Not recorded
- Pins
- Not recorded
- Details
- Si-diode: Dual, Schottky, 40V, 300mA, 100mW, <25pF
- Source
- Published code list
Is it dead? The meter test is below: Schottky diode.
74AUP1Z04GFNXPNot 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.
74AUP1Z04GMNXPNot 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.
74AUP1Z04GNNXPNot 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.
74AUP1Z04GSNXPNot 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.
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.
This part
Diode range and ohms range, part lifted.
Working, it reads
Depends on what it is. The datasheet, or an identical part, says.
Dead, it reads
- Between two pins, the same reading both ways, near 0 V with a continuous beep: shorted.
- Open between every pair of pins: failed open, or a part that reads open when working.
- 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.
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.
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.
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.
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