SMD code G21 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.
8 parts in SOT-23 are printed G21
Not sure which one you have?
Answer up to 4 quick questions and these 9 parts are ranked, with a meter test that settles it. It works on a dead part too.
DTD113ZCSOT-23Digital transistor (NPN, resistors built in), ROHMDigital transistor (NPN, resistors built in)ROHM
- What it is
- Digital transistor (NPN, resistors built in)
- Maker
- ROHM
- Package
- SOT-23
- Pins
- 3
- Details
- 500mA/50V Digital transistor (with built-in resistors)
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Digital transistor.
DTD113ZCASOT-23Digital transistor (NPN, resistors built in), Galaxy MicroelectronicsDigital transistor (NPN, resistors built in)Galaxy Microelectronics
- What it is
- Digital transistor (NPN, resistors built in)
- Maker
- Galaxy Microelectronics
- Package
- SOT-23
- Pins
- 3
- Details
- 50V, 500mA, NPN Bipolar Digital Transistor
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Digital transistor.
DTD113ZKSOT-23Digital transistor (NPN, resistors built in), ROHMDigital transistor (NPN, resistors built in)ROHM
- What it is
- Digital transistor (NPN, resistors built in)
- Maker
- ROHM
- Package
- SOT-23
- Pins
- 3
- Details
- 500mA/50V Digital transistor (with built-in resistors)
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Digital transistor.
TDTD113ZCASOT-23Digital transistor (NPN, resistors built in), Galaxy MicroelectronicsDigital transistor (NPN, resistors built in)Galaxy Microelectronics
- What it is
- Digital transistor (NPN, resistors built in)
- Maker
- Galaxy Microelectronics
- Package
- SOT-23
- Pins
- 3
- Details
- 50V, 500mA, NPN Bipolar Digital Transistor
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Digital transistor.
DTD113ZN3SOT-23Digital transistor (NPN, resistors built in), CYStekDigital transistor (NPN, resistors built in)CYStek
- What it is
- Digital transistor (NPN, resistors built in)
- Maker
- CYStek
- Package
- SOT-23
- Pins
- 3
- Details
- NPN digital (resistor-equipped) transistor, R1 1K, R2 10K
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Digital transistor.
DTD113ZKASOT-23ROHMNot recordedROHM
- What it is
- Not recorded
- Maker
- ROHM
- Package
- SOT-23
- Pins
- 3
- Details
- npn dtr 1k0 +10k 50V 500mA
- Source
- Published code list
Is it dead? The meter test is below: This part.
KIC73A21TSOT-23Voltage supervisor, KECVoltage supervisorKEC
- What it is
- Voltage supervisor
- Maker
- KEC
- Package
- SOT-23
- Pins
- 3
- Details
- Voltage detector IC: 2.1V±1%, -Reset PPO, Rdt=240ms
- Source
- Published code list
Is it dead? The meter test is below: Integrated circuit.
MMBZ4621SOT-23Zener diode, VishayZener diodeVishay
- What it is
- Zener diode
- Maker
- Vishay
- Package
- SOT-23
- Pins
- 3
- Details
- zener 350mW 5% 3.6V
- Source
- Published code list
Is it dead? The meter test is below: Zener diode.
1 more part has no package on record. Nothing rules it out, so it stays.
KIC73A21MVoltage supervisor, KECVoltage supervisorKEC
- What it is
- Voltage supervisor
- Maker
- KEC
- Package
- Not recorded
- Pins
- Not recorded
- Details
- Voltage detector IC: 2.1V±1%, -Reset PPO, Rdt=240ms
- 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.
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.
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.
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.
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.
Printed with a code easy to misread as G21
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 G21
For a marking with its end worn or burnt off. Each code has a page of its own.
Codes not listed here are printed on 13 more parts.
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