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.
Si2399DSprinted O1SOT-23P-channel MOSFET, 3 pins, VishayP-channel MOSFET3 pinsVishay
Printed O1 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
- Source
- Published code list
Is it dead? The meter test is below: P-channel MOSFET.
SiP809CREUADTprinted DISOT-23Voltage supervisor, 3 pins, VishayVoltage supervisor3 pinsVishay
Printed DI on the part. Easy to misread as QI-. Check that character with a loupe before you order anything.
- What it is
- Voltage supervisor
- Maker
- Vishay
- Package
- SOT-23
- Pins
- 3
- Details
- CMOS-IC: Voltage Detector 2,63V, -Reset Push-pull output 1,5ms
- Source
- Published code list
Is it dead? The meter test is below: Integrated circuit.
SiP809CSEUADTprinted DLSOT-23Voltage supervisor, 3 pins, VishayVoltage supervisor3 pinsVishay
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
- Vishay
- Package
- SOT-23
- Pins
- 3
- Details
- CMOS-IC: Voltage Detector 2,93V, -Reset Push-pull output 1,5ms
- Source
- Published code list
Is it dead? The meter test is below: Integrated circuit.
SP6641BEK-5.0printed Q1SOT-23DC-DC converter, 3 pins, SipexDC-DC converter3 pinsSipex
Printed Q1 on the part. Easy to misread as QI-. Check that character with a loupe before you order anything.
- What it is
- DC-DC converter
- Maker
- Sipex
- Package
- SOT-23
- Pins
- 3
- Details
- Step Up Converter
- Source
- Published code list
Is it dead? The meter test is below: Integrated circuit.
SSTPAD100printed 01SOT-233 pinsNot recorded3 pinsNot recorded
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
- Not recorded
- Package
- SOT-23
- Pins
- 3
- Details
- equivalent JPAD100
- Source
- Published code list
Is it dead? The meter test is below: This part.
TC54VC3102ECBprinted D1SOT-23Voltage supervisor, 3 pins, MicrochipVoltage supervisor3 pinsMicrochip
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
- Microchip
- Package
- SOT-23
- Pins
- 3
- Details
- CMOS-IC: Voltage Detector 3.1V±2%, -Reset Push-pull output
- Source
- Published code list
Is it dead? The meter test is below: Integrated circuit.
TZT5V6AWprinted DISOT-23Zener diode, 3 pinsZener diode3 pinsNot recorded
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
- Not recorded
- Package
- SOT-23
- Pins
- 3
- Details
- SMD Zener Diodes (Three Terminals) - 300mW
- Source
- Published code list
Is it dead? The meter test is below: Zener diode.
TZT17AWprinted DLSOT-23Zener diode, 3 pins, Taitron ComponentsZener diode3 pinsTaitron Components
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
- Taitron Components
- Package
- SOT-23
- Pins
- 3
- Source
- Published code list
Is it dead? The meter test is below: Zener diode.
XC61CC3102Mprinted D1SOT-233 pins, TorexNot recorded3 pinsTorex
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
- Torex
- Package
- SOT-23
- Pins
- 3
- Details
- CMOS-IC: Voltage Detector 3,1V, Reset Push-pull output
- Source
- Published code list
Is it dead? The meter test is below: Integrated circuit.
6 more parts have no package on record. Nothing rules them out, so they stay.
1N4148LW-Cprinted D1Switching diode, SeCoSSwitching diodeNot recordedSeCoS
Printed D1 on the part. Easy to misread as QI-. Check that character with a loupe before you order anything.
- What it is
- Switching diode
- Maker
- SeCoS
- Package
- Not recorded
- Pins
- Not recorded
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Silicon diode.
BFU610Fprinted D1RF transistor, 4 pins, NXPRF transistor4 pinsNXP
Printed D1 on the part. Easy to misread as QI-. Check that character with a loupe before you order anything.
- What it is
- RF transistor
- Maker
- NXP
- Package
- Not recorded
- Pins
- 4
- Details
- NPN wideband silicon RF transistor
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Bipolar transistor.
BGU6005/N2printed D1RF amplifier (MMIC), 6 pins, NXPRF amplifier (MMIC)6 pinsNXP
Printed D1 on the part. Easy to misread as QI-. Check that character with a loupe before you order anything.
- What it is
- RF amplifier (MMIC)
- Maker
- NXP
- Package
- Not recorded
- Pins
- 6
- Details
- Low Noise Amplifier MMIC for GPS, GLONASS, Galileo and Compass
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: RF amplifier.
DS520-40A1printed D1Schottky diode, JSCJSchottky diodeNot recordedJSCJ
Printed D1 on the part. Easy to misread as QI-. Check that character with a loupe before you order anything.
- What it is
- Schottky diode
- Maker
- JSCJ
- Package
- Not recorded
- Pins
- Not recorded
- Details
- Schottky diode, 40 V, 0.2 A
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Schottky diode.
ESDALC6V1-1BU2printed D1TVS diode, STMicroelectronicsTVS diodeNot recordedSTMicroelectronics
Printed D1 on the part. Easy to misread as QI-. Check that character with a loupe before you order anything.
- What it is
- TVS diode
- Maker
- STMicroelectronics
- Package
- Not recorded
- Pins
- Not recorded
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: TVS or ESD protection diode.
GSRB520B40printed D1Schottky diode, Good-ArkSchottky diodeNot recordedGood-Ark
Printed D1 on the part. Easy to misread as QI-. Check that character with a loupe before you order anything.
- What it is
- Schottky diode
- Maker
- Good-Ark
- Package
- Not recorded
- Pins
- Not recorded
- Details
- Schottky diode, 40 V, 200 mA
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Schottky 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.
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.
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.
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.
Bipolar transistor
Diode range, part lifted or its base leg off the pad.
Working, it reads
From the base, one probe colour reads about 0.6 to 0.75 V to the emitter and to the collector, and open the other way round. Collector to emitter reads open both ways.
Dead, it reads
- Collector to emitter the same both ways, near 0 V with a continuous beep: shorted. The commonest failure.
- The base the same both ways to another pin, near 0 V or a middling value: a shorted junction.
- Only one junction reads, or none: a junction has failed open. It then looks like a diode.
- A reading the wrong way round, where it should be open: 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 pair of diodes with a common pin reads just like a transistor, and some transistors carry a built-in diode or resistor. The datasheet says which.
A dead part still carries its marking. A short or an open says it has failed, not that it is a different part.
RF amplifier
Voltage, board powered, on the output pin that the bias resistor or choke feeds.
Working, it reads
The output pin sits at the device voltage the datasheet gives, a few volts, below the supply.
Dead, it reads
- Output pin at 0 V, or near 0 Ω to ground with the power off: shorted inside.
- Output pin at the full supply voltage: open inside, no current flowing.
- On the board:
- Measured on the board with power on; the bias network is part of the reading.
- 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 figures depend on the part and its bias resistor. 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.
Schottky diode
Diode range, part lifted or one leg off the pad. Red probe on the anode.
Working, it reads
About 0.15 to 0.45 V anode to cathode, roughly half a silicon diode, and open the other way.
Dead, it reads
- The same reading both ways round, near 0 V with a continuous beep or the same middling value: shorted.
- A reading the wrong way round as well: leaky.
- Open both ways: failed open.
- 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 large Schottky can read about 0.1 V forward and beep like a short, and leaks a little the wrong way when good, more when warm. It is shorted only if it reads the same both ways. Measure it cold, beside an identical cold one.
A dead part still carries its marking. A short or an open says it has failed, not that it is a different part.
TVS or ESD protection diode
Diode range, from the protected line to ground, part lifted if you can.
Working, it reads
A one-way part reads about 0.6 to 0.8 V forward and open in reverse. A two-way part reads open both ways. Arrays with several lines read as the datasheet's diagram draws them.
Dead, it reads
- From the line to ground, the same reading both ways, near 0 V with a continuous beep: shorted.
- A reading both ways on a one-way part: leaky.
- A one-way part open both ways: failed open.
- On the board
- , a line reading shorted to ground can be this part or anything else on that line. Lift it: if the short goes with it, it has failed.
- Compare:
- The same part on the next line or connector pin is the healthy reading to compare with.
- Watch for:
- A two-way part reads open both ways when it is good, exactly like one that has failed open. The meter cannot tell them apart; an identical part on the next line can.
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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