SMD code QI- in SOT-23
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.
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.
Nothing is printed exactly QI-
These parts are printed with a character that is easy to misread as what you typed. The odd one out is marked on each.
all SOT-23, 3 pins. What differs:
MCP100T-315Iprinted QLSOT-23Voltage supervisor, MicrochipVoltage supervisorMicrochip
Printed QL on the part. Easy to misread as QI-. Check that character with a loupe before you order anything.
- What it is
- Voltage supervisor
- Maker
- Microchip
- Package
- SOT-23
- Pins
- 3
- Details
- CMOS-IC: Voltage Detector 3,15V, -Reset Push-pull output
- Source
- Published code list
Is it dead? The meter test is below: Integrated circuit.
MCP100T-315I/TTprinted QLSOT-23MicrochipNot recordedMicrochip
Printed QL on the part. Easy to misread as QI-. Check that character with a loupe before you order anything.
- What it is
- Not recorded
- Maker
- Microchip
- Package
- SOT-23
- Pins
- 3
- Source
- Published code list
Is it dead? The meter test is below: This part.
MEZ03-5.6-T2printed DISOT-23Zener diode, Matsuki Electronic CompanyZener diodeMatsuki Electronic Company
Printed DI on the part. Easy to misread as QI-. Check that character with a loupe before you order anything.
- What it is
- Zener diode
- Maker
- Matsuki Electronic Company
- Package
- SOT-23
- Pins
- 3
- Details
- Zener diode: 5.32..5.88V, Izt=5mA, Zzt=40, 300mW
- Source
- Published code list
Is it dead? The meter test is below: Zener diode.
MEZ03-6.8-T2printed DllSOT-23Zener diode, Matsuki Electronic CompanyZener diodeMatsuki Electronic Company
Printed Dll on the part. Easy to misread as QI-. Check that character with a loupe before you order anything.
- What it is
- Zener diode
- Maker
- Matsuki Electronic Company
- Package
- SOT-23
- Pins
- 3
- Details
- Zener diode: 6.46..7.14V, Izt=5mA, Zzt=8, 300mW
- Source
- Published code list
Is it dead? The meter test is below: Zener diode.
MEZ03-17-T2printed DLSOT-23Zener diode, Matsuki Electronic CompanyZener diodeMatsuki Electronic Company
Printed DL on the part. Easy to misread as QI-. Check that character with a loupe before you order anything.
- What it is
- Zener diode
- Maker
- Matsuki Electronic Company
- Package
- SOT-23
- Pins
- 3
- Details
- Zener diode: 16.15..17.85V, Izt=5mA, Zzt=40, 300mW
- Source
- Published code list
Is it dead? The meter test is below: Zener diode.
NHDTC143ZTprinted QL-SOT-23Digital transistor (NPN, resistors built in), NXPDigital transistor (NPN, resistors built in)NXP
Printed QL- on the part. Easy to misread as QI-. Check that character with a loupe before you order anything.
- What it is
- Digital transistor (NPN, resistors built in)
- Maker
- NXP
- Package
- SOT-23
- Pins
- 3
- Details
- NPN transistor: Sw, 80V, 100mA, 350mW, R1/R2=4.7k/47k
- Source
- Published code list
Is it dead? The meter test is below: Digital transistor.
PDTA143EKprinted 01SOT-23NXPNot recordedNXP
Printed 01 on the part. Easy to misread as QI-. Check that character with a loupe before you order anything.
- What it is
- Not recorded
- Maker
- NXP
- Package
- SOT-23
- Pins
- 3
- Details
- Si-pnp-Digi: Sw, 50V, 100mA, 250mW, R1/R2=4.7k/4.7k
- Source
- Published code list
Is it dead? The meter test is below: This part.
R3111N312Aprinted D1SOT-23Nisshinbo Micro DevicesNot recordedNisshinbo Micro Devices
Printed D1 on the part. Easy to misread as QI-. Check that character with a loupe before you order anything.
- What it is
- Not recorded
- Maker
- Nisshinbo Micro Devices
- Package
- SOT-23
- Pins
- 3
- Details
- CMOS-IC: Voltage Detector 3.1V±2.0%, Reset Push-pull output
- Source
- Published code list
Is it dead? The meter test is below: Integrated circuit.
R3130N41ECprinted D1SOT-23Nisshinbo Micro DevicesNot recordedNisshinbo Micro Devices
Printed D1 on the part. Easy to misread as QI-. Check that character with a loupe before you order anything.
- What it is
- Not recorded
- Maker
- Nisshinbo Micro Devices
- Package
- SOT-23
- Pins
- 3
- Details
- CMOS-IC: Voltage Detector 4,1V, -Reset Open drain output, 240ms
- Source
- Published code list
Is it dead? The meter test is below: Integrated circuit.
R3130N44AAprinted Q1SOT-23Nisshinbo Micro DevicesNot recordedNisshinbo Micro Devices
Printed Q1 on the part. Easy to misread as QI-. Check that character with a loupe before you order anything.
- What it is
- Not recorded
- Maker
- Nisshinbo Micro Devices
- Package
- SOT-23
- Pins
- 3
- Details
- CMOS-IC: Voltage Detector 4,4V, -Reset Push-pull output, 50ms
- Source
- Published code list
Is it dead? The meter test is below: Integrated circuit.
R3131N40ACprinted 0LSOT-23Nisshinbo Micro DevicesNot recordedNisshinbo Micro Devices
Printed 0L on the part. Easy to misread as QI-. Check that character with a loupe before you order anything.
- What it is
- Not recorded
- Maker
- Nisshinbo Micro Devices
- Package
- SOT-23
- Pins
- 3
- Details
- CMOS-IC: Voltage Detector 4V, Reset Open drain output, 50ms
- Source
- Published code list
Is it dead? The meter test is below: Integrated circuit.
RT9809-16CVprinted D1SOT-23Voltage supervisor, RichtekVoltage supervisorRichtek
Printed D1 on the part. Easy to misread as QI-. Check that character with a loupe before you order anything.
- What it is
- Voltage supervisor
- Maker
- Richtek
- Package
- SOT-23
- Pins
- 3
- Details
- Voltage detector IC: 1.6V±2%, -Reset PPO
- Source
- Published code list
Is it dead? The meter test is below: Integrated circuit.
RT9809-35CVprinted DLSOT-23Voltage supervisor, RichtekVoltage supervisorRichtek
Printed DL on the part. Easy to misread as QI-. Check that character with a loupe before you order anything.
- What it is
- Voltage supervisor
- Maker
- Richtek
- Package
- SOT-23
- Pins
- 3
- Details
- Voltage detector IC: 3.5V±2%, -Reset PPO
- Source
- Published code list
Is it dead? The meter test is below: Integrated circuit.
Si2321DSprinted D1SOT-23P-channel MOSFETP-channel MOSFETNot recorded
Printed D1 on the part. Easy to misread as QI-. Check that character with a loupe before you order anything.
- What it is
- P-channel MOSFET
- Maker
- Not recorded
- Package
- SOT-23
- Pins
- 3
- Details
- P-channel MOSFET, 20 V, 4.2 A
- Source
- Published code list
Is it dead? The meter test is below: P-channel MOSFET.
SI2321DSprinted D1SOT-23P-channel MOSFET, VishayP-channel MOSFETVishay
Printed D1 on the part. Easy to misread as QI-. Check that character with a loupe before you order anything.
- What it is
- P-channel MOSFET
- Maker
- Vishay
- Package
- SOT-23
- Pins
- 3
- Details
- MOSFET p-type: V-MOS, LogL, 20V, 4.3A, 1.25W, <44m(4.3A), 15/60ns
- Source
- Published code list
Is it dead? The meter test is below: P-channel MOSFET.
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.
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.
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.
Digital transistor
Ohms range, part lifted. The datasheet gives the built-in resistors: R1 in series with the base, R2 from base to emitter.
Working, it reads
Base to emitter reads about R1 plus R2 either way round, about 20 kΩ on a 10 k and 10 k part, give or take their wide tolerance. Collector to emitter reads open. A part with no R2 reads a junction behind R1 one way instead.
Dead, it reads
- Collector to emitter the same both ways, near 0 Ω with a continuous beep: shorted.
- From the base, open or far above R1 plus R2: R1 has failed. Static damage shows here most often.
- Base to emitter near 0 Ω: failed short.
- 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:
- The readings depend on the resistor values, so an identical part elsewhere on the board is the surest reference. Measure it the same way.
- Watch for:
- On the diode range a good part with 10 kΩ resistors reads open on every pair, so a good part looks dead there. Use the ohms range.
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.
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