SMD code 304
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.
304 on a chip resistor
300 kΩ
300 kΩ resistor, 5%
30 followed by 4 zeros. Three digits is normally the 5% series. The same marking also reads as 300 nF on a capacitor, and nothing in the code says which; the body of the part does.
Other readings of the same characters, most likely first
- 300 nF capacitor
Check it with a meter
Lift one end and measure across it. A good one reads 300 kΩ within 5%. Measuring it in circuit reads the parallel combination of everything around it, which is almost always lower, never higher: well above 300 kΩ on the board is a fault. Open, or well above 300 kΩ, means it has failed: burnt, cracked or corroded. That does not change what to fit: the marking still says 300 kΩ. A burnt resistor usually means the part it feeds drew too much, so find that before fitting a new one.
On a transistor or diode body (USP-6C, SMC, SOT-23-5), 304 is a part code instead. Those parts are listed below.
11 parts are printed 304
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.
ACGRB304-HFSMBRectifier, 2 pins, ComchipRectifierSMB2 pinsComchip
- What it is
- Rectifier
- Maker
- Comchip
- Package
- SMB
- Pins
- 2
- Details
- 400 V, 3 A rectifier
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Silicon diode.
ACGRC304-HFSMCRectifier, 2 pins, ComchipRectifierSMC2 pinsComchip
- What it is
- Rectifier
- Maker
- Comchip
- Package
- SMC
- Pins
- 2
- Details
- 400 V, 3 A rectifier
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Silicon diode.
ACSFB304-HFSMBRectifier, 2 pins, ComchipRectifierSMB2 pinsComchip
- What it is
- Rectifier
- Maker
- Comchip
- Package
- SMB
- Pins
- 2
- Details
- 200 V, 3 A rectifier
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Silicon diode.
CGRB304-HFSMBRectifier, 2 pins, ComchipRectifierSMB2 pinsComchip
- What it is
- Rectifier
- Maker
- Comchip
- Package
- SMB
- Pins
- 2
- Details
- 400 V, 3 A rectifier
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Silicon diode.
CSFB304-HFSMBRectifier, 2 pins, ComchipRectifierSMB2 pinsComchip
- What it is
- Rectifier
- Maker
- Comchip
- Package
- SMB
- Pins
- 2
- Details
- 200 V, 3 A rectifier
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Silicon diode.
CURC304-HFSMCRectifier, 2 pins, ComchipRectifierSMC2 pinsComchip
- What it is
- Rectifier
- Maker
- Comchip
- Package
- SMC
- Pins
- 2
- Details
- 400 V, 3 A rectifier
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Silicon diode.
FDV304PSOT-23P-channel MOSFET, 3 pins, UMWP-channel MOSFETSOT-233 pinsUMW
- What it is
- P-channel MOSFET
- Maker
- UMW
- Package
- SOT-23
- Pins
- 3
- Details
- P-channel MOSFET, 20 V, 2.3 A
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: P-channel MOSFET.
XC6104A135MRSOT-23-5Voltage supervisor, 5 pins, TorexVoltage supervisorSOT-23-55 pinsTorex
- What it is
- Voltage supervisor
- Maker
- Torex
- Package
- SOT-23-5
- Pins
- 5
- Details
- CMOS-IC: VDet 3.5V, 5%, Hst, ±Reset PPO, Wt=6.25ms, Rt=3.13ms
- Source
- Published code list
Is it dead? The meter test is below: Integrated circuit.
XC6403AA04MSOT-23-55 pins, TorexNot recordedSOT-23-55 pinsTorex
- What it is
- Not recorded
- Maker
- Torex
- Package
- SOT-23-5
- Pins
- 5
- Details
- Linear voltage regulator with volatge detector: LDO, 1.8V±2%, 300mA, Vdi=2.0V, -Reset ODO, +CE, PDR
- Source
- Published code list
Is it dead? The meter test is below: Voltage regulator.
XC6403AA04PSOT-89-55 pins, TorexNot recordedSOT-89-55 pinsTorex
- What it is
- Not recorded
- Maker
- Torex
- Package
- SOT-89-5
- Pins
- 5
- Details
- Linear voltage regulator with volatge detector: LDO, 1.8V±2%, 300mA, Vdi=2.0V, -Reset ODO, +CE, PDR
- Source
- Published code list
Is it dead? The meter test is below: Voltage regulator.
1 more part has no package on record
TCK304GLoad switch, ToshibaLoad switchNot recordedNot recordedToshiba
- What it is
- Load switch
- Maker
- Toshiba
- Package
- Not recorded
- Pins
- Not recorded
- Details
- 28 V, Single input - Single Output Load Switch IC with Over Voltage Protection
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Load switch.
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.
P-channel MOSFET
Diode range, part lifted. Test drain to source first, then short gate to source and test again.
Working, it reads
Red probe on the drain, black on the source: about 0.4 to 0.9 V, the body diode. Open the other way. The gate reads open to both other pins, both ways.
Dead, it reads
- Drain to source the same both ways, near 0 V with a continuous beep, and still so after shorting gate to source: shorted. The classic failure.
- The gate reads low to source or drain: gate shorted. Often all three pins end up shorted together.
- No body diode at all: failed open.
- On the board
- the gate usually has a resistor to the source, so gate to source reads that resistor, which is not a fault. Lift a leg to be sure.
- 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 diode range can charge the gate enough to turn the part on, and then drain to source reads near 0 both ways on a good part. Short gate to source and test again before you condemn it.
A dead part still carries its marking. A short or an open says it has failed, not that it is a different part.
Load switch
Voltage, board powered, black probe on ground.
Working, it reads
Switched on, the output pin sits at the input voltage. Switched off, it sits near 0 V.
Dead, it reads
- Output at the input voltage while switched off: the pass element has shorted.
- Input present and switched on, no output: failed open, or shut down into a shorted load. Power off and measure output to ground.
- On the board:
- An output near 0 Ω to ground is usually the load. Lift the output pin to see which.
- 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 pinout and whether the enable is active high or low differ between parts. 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.
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.
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.
Printed with a code easy to misread as 304
One character differs, and it is one that is easy to confuse under a lamp. Each code has a page of its own.
Codes that begin with 304
For a marking with its end worn or burnt off. Each code has a page of its own.
Codes not listed here are printed on 66 more parts.
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