SMD code R9 in SOT-323

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.

R9 on a chip resistor

0.9 Ω

0.9 Ω resistor

The R stands in for the decimal point, which is how sub-ohm and fractional values are printed.

Check it with a meter

Lift one end and measure across it. A good one reads 0.9 Ω. Measuring it in circuit reads the parallel combination of everything around it, which is almost always lower, never higher: well above 0.9 Ω on the board is a fault. Open, or well above 0.9 Ω, means it has failed: burnt, cracked or corroded. That does not change what to fit: the marking still says 0.9 Ω. A burnt resistor usually means the part it feeds drew too much, so find that before fitting a new one.

On a transistor or diode body (SOT-23, SOT-23-5, SOT-89), R9 is a part code instead. Those parts are listed below.

3 parts in SOT-323 are printed R9

Not sure which one you have?

Answer up to 4 quick questions and these 26 parts are ranked, with a meter test that settles it. It works on a dead part too.

1SS393SOT-323Schottky diode, 3 pins, ToshibaSchottky diode3 pinsToshiba
What it is
Schottky diode
Maker
Toshiba
Package
SOT-323
Pins
3
Details
dual cc schottky 40V 0.1A
Source
Published code list
Is it dead? The meter test is below: Schottky diode.
AP8822C-09GTSOT-323Voltage supervisor, 3 pins, Anwell SemiconductorVoltage supervisor3 pinsAnwell Semiconductor
What it is
Voltage supervisor
Maker
Anwell Semiconductor
Package
SOT-323
Pins
3
Details
Voltage detector IC: 0.9V±2%, -Reset PPO, Rdt=200ms, H-free
Source
Published code list
Is it dead? The meter test is below: Integrated circuit.
AP8822C-09PTSOT-323Voltage supervisor, 3 pins, Anwell SemiconductorVoltage supervisor3 pinsAnwell Semiconductor
What it is
Voltage supervisor
Maker
Anwell Semiconductor
Package
SOT-323
Pins
3
Details
Voltage detector IC: 0.9V±2%, -Reset PPO, Rdt=200ms
Source
Published code list
Is it dead? The meter test is below: Integrated circuit.
12 more parts have no package on record. Nothing rules them out, so they stay.
- BAR90-02LRHPIN diode, InfineonPIN diodeNot recordedInfineon
  What it is
  PIN diode
  Maker
  Infineon
  Package
  Not recorded
  Pins
  Not recorded
  Source
  Manufacturer datasheet
  Is it dead? The meter test is below: PIN diode or varicap.
  Datasheetfor BAR90-02LRH, opens in a new tab
- RS1KMRectifier, Taiwan SemiconductorRectifierNot recordedTaiwan Semiconductor
  What it is
  Rectifier
  Maker
  Taiwan Semiconductor
  Package
  Not recorded
  Pins
  Not recorded
  Source
  Manufacturer datasheet
  Is it dead? The meter test is below: Silicon diode.
  Datasheetfor RS1KM, opens in a new tab
- TST014C-393WSSchottky diode, Taitron ComponentsSchottky diodeNot recordedTaitron Components
  What it is
  Schottky diode
  Maker
  Taitron Components
  Package
  Not recorded
  Pins
  Not recorded
  Details
  Schottky Barrier Diodes (Multiple Terminals)
  Source
  Manufacturer datasheet
  Is it dead? The meter test is below: Schottky diode.
  Datasheetfor TST014C-393WS, opens in a new tab
- 74AXP1G09GMNXPNot recordedNot recordedNXP
  What it is
  Not recorded
  Maker
  NXP
  Package
  Not recorded
  Pins
  Not recorded
  Details
  CMOS logic IC: 2-input AND gate (ODO)
  Source
  Published code list
  Is it dead? The meter test is below: Integrated circuit.
- 74AXP1G09GNNXPNot recordedNot recordedNXP
  What it is
  Not recorded
  Maker
  NXP
  Package
  Not recorded
  Pins
  Not recorded
  Details
  CMOS logic IC: 2-input AND gate (ODO)
  Source
  Published code list
  Is it dead? The meter test is below: Integrated circuit.
- 74AXP1G09GSNXPNot recordedNot recordedNXP
  What it is
  Not recorded
  Maker
  NXP
  Package
  Not recorded
  Pins
  Not recorded
  Details
  CMOS logic IC: 2-input AND gate (ODO)
  Source
  Published code list
  Is it dead? The meter test is below: Integrated circuit.
- 74AXP1G09GXNXPNot recordedNot recordedNXP
  What it is
  Not recorded
  Maker
  NXP
  Package
  Not recorded
  Pins
  Not recorded
  Details
  CMOS logic IC: 2-input AND gate (ODO)
  Source
  Published code list
  Is it dead? The meter test is below: Integrated circuit.
- 74AXP1G98GMNXPNot recordedNot recordedNXP
  What it is
  Not recorded
  Maker
  NXP
  Package
  Not recorded
  Pins
  Not recorded
  Details
  CMOS logic IC: Configurable multiple function gate
  Source
  Published code list
  Is it dead? The meter test is below: Integrated circuit.
- 74AXP1G98GNNXPNot recordedNot recordedNXP
  What it is
  Not recorded
  Maker
  NXP
  Package
  Not recorded
  Pins
  Not recorded
  Details
  CMOS logic IC: Configurable multiple function gate
  Source
  Published code list
  Is it dead? The meter test is below: Integrated circuit.
- 74AXP1G98GSNXPNot recordedNot recordedNXP
  What it is
  Not recorded
  Maker
  NXP
  Package
  Not recorded
  Pins
  Not recorded
  Details
  CMOS logic IC: Configurable multiple function gate
  Source
  Published code list
  Is it dead? The meter test is below: Integrated circuit.
- AP8822C-09GIVoltage supervisor, Anwell SemiconductorVoltage supervisorNot recordedAnwell Semiconductor
  What it is
  Voltage supervisor
  Maker
  Anwell Semiconductor
  Package
  Not recorded
  Pins
  Not recorded
  Details
  Voltage detector IC: 0.9V±2%, -Reset PPO, 200ms Rt delay, H-free
  Source
  Published code list
  Is it dead? The meter test is below: Integrated circuit.
- AP8822C-09GSVoltage supervisor, Anwell SemiconductorVoltage supervisorNot recordedAnwell Semiconductor
  What it is
  Voltage supervisor
  Maker
  Anwell Semiconductor
  Package
  Not recorded
  Pins
  Not recorded
  Details
  Voltage detector IC: 0.9V±2%, -Reset PPO, 200ms Rt delay, H-free
  Source
  Published code list
  Is it dead? The meter test is below: Integrated circuit.

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.

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.

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.

PIN diode or varicap

Diode range, part lifted or one leg off the pad. Red probe on the anode.

Working, it reads

About 0.6 to 0.9 V anode to cathode, 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.
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 varicap that has drifted in capacitance reads normal on a meter. Only a capacitance meter or the tuning itself shows it.

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.

Codes that begin with R9

For a marking with its end worn or burnt off. Each code has a page of its own.

Did you find your part?

Open this in the search to correct a character or try another package.