SMD code 4QB
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.
13 parts are printed 4QB
Not sure which one you have?
Answer up to 4 quick questions and these 13 parts are ranked, with a meter test that settles it. It works on a dead part too.
LDO regulator. What differs:
AP6233S-33NLFGASOT-23-55 pins, Anwell SemiconductorSOT-23-55 pinsAnwell Semiconductor
- What it is
- LDO regulator
- Maker
- Anwell Semiconductor
- Package
- SOT-23-5
- Pins
- 5
- Details
- Linear voltage regulator IC: LDO, 3.3V±2%, 300mA, Fst -CE, CL, H-free
- Source
- Published code list
Is it dead? The meter test is below: Voltage regulator.
AP6233S-33NLFGA1SOT-23-55 pins, Anwell SemiconductorSOT-23-55 pinsAnwell Semiconductor
- What it is
- LDO regulator
- Maker
- Anwell Semiconductor
- Package
- SOT-23-5
- Pins
- 5
- Details
- Linear voltage regulator IC: LDO, 3.3V±1%, 300mA, Fst -CE, CL, H-free
- Source
- Published code list
Is it dead? The meter test is below: Voltage regulator.
AP6233S-33NLFGPSOT-3535 pins, Anwell SemiconductorSOT-3535 pinsAnwell Semiconductor
- What it is
- LDO regulator
- Maker
- Anwell Semiconductor
- Package
- SOT-353
- Pins
- 5
- Details
- Linear voltage regulator IC: LDO, 3.3V±2%, 300mA, Fst -CE, CL, H-free
- Source
- Published code list
Is it dead? The meter test is below: Voltage regulator.
AP6233S-33NLFGP1SOT-3535 pins, Anwell SemiconductorSOT-3535 pinsAnwell Semiconductor
- What it is
- LDO regulator
- Maker
- Anwell Semiconductor
- Package
- SOT-353
- Pins
- 5
- Details
- Linear voltage regulator IC: LDO, 3.3V±1%, 300mA, Fst -CE, CL, H-free
- Source
- Published code list
Is it dead? The meter test is below: Voltage regulator.
AP6233S-33NLFPASOT-23-55 pins, Anwell SemiconductorSOT-23-55 pinsAnwell Semiconductor
- What it is
- LDO regulator
- Maker
- Anwell Semiconductor
- Package
- SOT-23-5
- Pins
- 5
- Details
- Linear voltage regulator IC: LDO, 3.3V±2%, 300mA, Fst -CE, CL
- Source
- Published code list
Is it dead? The meter test is below: Voltage regulator.
AP6233S-33NLFPA1SOT-23-55 pins, Anwell SemiconductorSOT-23-55 pinsAnwell Semiconductor
- What it is
- LDO regulator
- Maker
- Anwell Semiconductor
- Package
- SOT-23-5
- Pins
- 5
- Details
- Linear voltage regulator IC: LDO, 3.3V±1%, 300mA, Fst -CE, CL
- Source
- Published code list
Is it dead? The meter test is below: Voltage regulator.
AP6233S-33NLFPPSOT-3535 pins, Anwell SemiconductorSOT-3535 pinsAnwell Semiconductor
- What it is
- LDO regulator
- Maker
- Anwell Semiconductor
- Package
- SOT-353
- Pins
- 5
- Details
- Linear voltage regulator IC: LDO, 3.3V±2%, 300mA, Fst -CE, CL
- Source
- Published code list
Is it dead? The meter test is below: Voltage regulator.
AP6233S-33NLFPP1SOT-3535 pins, Anwell SemiconductorSOT-3535 pinsAnwell Semiconductor
- What it is
- LDO regulator
- Maker
- Anwell Semiconductor
- Package
- SOT-353
- Pins
- 5
- Details
- Linear voltage regulator IC: LDO, 3.3V±1%, 300mA, Fst -CE, CL
- Source
- Published code list
Is it dead? The meter test is below: Voltage regulator.
UM1431S5-49SOT-23-55 pins, Union SemiconductorSOT-23-55 pinsUnion Semiconductor
- What it is
- LDO regulator
- Maker
- Union Semiconductor
- Package
- SOT-23-5
- Pins
- 5
- Details
- Linear voltage regulator IC: LDO, 4.9±3%, 100mA
- Source
- Published code list
Is it dead? The meter test is below: Voltage regulator.
4 more parts have no package on record
AP6233S-33NLFGUAnwell SemiconductorNot recordedNot recordedAnwell Semiconductor
- What it is
- LDO regulator
- Maker
- Anwell Semiconductor
- Package
- Not recorded
- Pins
- Not recorded
- Details
- Linear voltage regulator IC: LDO, 3.3V±2%, 300mA, Fst -CE, CL, H-free
- Source
- Published code list
Is it dead? The meter test is below: Voltage regulator.
AP6233S-33NLFGU1Anwell SemiconductorNot recordedNot recordedAnwell Semiconductor
- What it is
- LDO regulator
- Maker
- Anwell Semiconductor
- Package
- Not recorded
- Pins
- Not recorded
- Details
- Linear voltage regulator IC: LDO, 3.3V±1%, 300mA, Fst -CE, CL, H-free
- Source
- Published code list
Is it dead? The meter test is below: Voltage regulator.
AP6233S-33NLFPUAnwell SemiconductorNot recordedNot recordedAnwell Semiconductor
- What it is
- LDO regulator
- Maker
- Anwell Semiconductor
- Package
- Not recorded
- Pins
- Not recorded
- Details
- Linear voltage regulator IC: LDO, 3.3V±2%, 300mA, Fst -CE, CL
- Source
- Published code list
Is it dead? The meter test is below: Voltage regulator.
AP6233S-33NLFPU1Anwell SemiconductorNot recordedNot recordedAnwell Semiconductor
- What it is
- LDO regulator
- Maker
- Anwell Semiconductor
- Package
- Not recorded
- Pins
- Not recorded
- Details
- Linear voltage regulator IC: LDO, 3.3V±1%, 300mA, Fst -CE, CL
- Source
- Published code list
Is it dead? The meter test is below: Voltage regulator.
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.
Printed with a code easy to misread as 4QB
One character differs, and it is one that is easy to confuse under a lamp. Each code has a page of its own.
Codes not listed here are printed on 2 more parts.
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