SMD code 303 in SMC
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.
2 parts in SMC are printed 303
Not sure which one you have?
Answer up to 4 quick questions and these 5 parts are ranked, with a meter test that settles it. It works on a dead part too.
ACGRC303-HFSMCRectifier, ComchipRectifierComchip
- What it is
- Rectifier
- Maker
- Comchip
- Package
- SMC
- Pins
- 2
- Details
- 200 V, 3 A rectifier
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Silicon diode.
CURC303-HFSMCRectifier, ComchipRectifierComchip
- What it is
- Rectifier
- Maker
- Comchip
- Package
- SMC
- Pins
- 2
- Details
- 200 V, 3 A rectifier
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Silicon diode.
3 more parts have no package on record. Nothing rules them out, so they stay.
FDC6303NDual N-channel MOSFET, onsemiDual N-channel MOSFETonsemi
- What it is
- Dual N-channel MOSFET
- Maker
- onsemi
- Package
- Not recorded
- Pins
- Not recorded
- Details
- Digital FET, Dual N-Channel
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: N-channel MOSFET pair.
TCK303GLoad switch, ToshibaLoad switchToshiba
- 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.
HZU30L-3Zener diode, RenesasZener diodeRenesas
- What it is
- Zener diode
- Maker
- Renesas
- Package
- Not recorded
- Pins
- Not recorded
- Details
- Z-diode: 30.2..31.6V, 150mW
- Source
- Published code list
Is it dead? The meter test is below: Zener 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.
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.
N-channel MOSFET pair
Diode range, part lifted. Test drain to source first, then short gate to source and test again. Test each MOSFET on its own pins, as the datasheet's pinout gives them.
Working, it reads
Red probe on the source, black on the drain: 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. A drain short can be the load. 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.
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.
Printed with a code easy to misread as 303
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 303
For a marking with its end worn or burnt off. Each code has a page of its own.
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