SMD code L29B
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.
3 parts are printed L29B
Not sure which one you have?
Answer up to 4 quick questions and these 3 parts are ranked, with a meter test that settles it. It works on a dead part too.
APL3529BDFNLoad switch, AnpecLoad switchDFNNot recordedAnpec
- What it is
- Load switch
- Maker
- Anpec
- Package
- DFN
- Pins
- Not recorded
- Details
- Ultra-Low On-Resistance, Power Load Switch With Soft Start
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Load switch.
LP2982IM5-4.0SOT-23-55 pins, National SemiconductorNot recordedSOT-23-55 pinsNational Semiconductor
- What it is
- Not recorded
- Maker
- National Semiconductor
- Package
- SOT-23-5
- Pins
- 5
- Details
- VR-IC: Ultra-LDO, CE, 4V, 50mA
- Source
- Published code list
Is it dead? The meter test is below: Voltage regulator.
R1173H291BSOT-89-55 pins, Nisshinbo Micro DevicesNot recordedSOT-89-55 pinsNisshinbo Micro Devices
- What it is
- Not recorded
- Maker
- Nisshinbo Micro Devices
- Package
- SOT-89-5
- Pins
- 5
- Details
- VR-IC: LDO, CE, 2.9V±2%, 1A
- 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.
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.
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 L29B
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 L29B
For a marking with its end worn or burnt off. Each code has a page of its own.
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