SMD code MM 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.
4 parts in SOT-23 are printed MM
Not sure which one you have?
Answer up to 4 quick questions and these 29 parts are ranked, with a meter test that settles it. It works on a dead part too.
BZX84C68CCSOT-23Zener diode, JinYu semiconductorZener diodeJinYu semiconductor
- What it is
- Zener diode
- Maker
- JinYu semiconductor
- Package
- SOT-23
- Pins
- 3
- Details
- Zener diode: Dual, 64..72V, Zzt=240, Izt=2mA, 350mW
- Source
- Published code list
Is it dead? The meter test is below: Zener diode.
DDZX9715SOT-23Zener diode, Diodes IncorporatedZener diodeDiodes Incorporated
- What it is
- Zener diode
- Maker
- Diodes Incorporated
- Package
- SOT-23
- Pins
- 3
- Details
- Z-diode: 36V±5%, 500mW
- Source
- Published code list
Is it dead? The meter test is below: Zener diode.
MCP111T-475E/TTSOT-23MicrochipNot recordedMicrochip
- 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.
PT7M6242CLTA3ESOT-23Voltage supervisor, Pericom TechnologyVoltage supervisorPericom Technology
- What it is
- Voltage supervisor
- Maker
- Pericom Technology
- Package
- SOT-23
- Pins
- 3
- Details
- Voltage detector IC: 4.2V±1.5%, -Reset PPO, L-free
- Source
- Published code list
Is it dead? The meter test is below: Integrated circuit.
11 more parts have no package on record. Nothing rules them out, so they stay.
BAR64-02LPIN diode, InfineonPIN diodeInfineon
- 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.
HFCG-3800+RF filter, Mini-CircuitsRF filterMini-Circuits
- What it is
- RF filter
- Maker
- Mini-Circuits
- Package
- Not recorded
- Pins
- Not recorded
- Details
- LTCC filter, 4200-18000 MHz
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: This part.
NCP163AMX280LDO regulator, onsemiLDO regulatoronsemi
- What it is
- LDO regulator
- Maker
- onsemi
- Package
- Not recorded
- Pins
- Not recorded
- Details
- LDO Regulator - Ultra-Low Noise, High PSRR, RF and Analog Circuits
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Voltage regulator.
NCV8163AMX280LDO regulator, onsemiLDO regulatoronsemi
- What it is
- LDO regulator
- Maker
- onsemi
- Package
- Not recorded
- Pins
- Not recorded
- Details
- LDO Regulator - Ultra-Low Noise, High PSRR, RF and Analog Circuits
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Voltage regulator.
SMF33A-MFHTVS diode, Formosa MicrosemiTVS diodeFormosa Microsemi
- What it is
- TVS diode
- Maker
- Formosa Microsemi
- Package
- Not recorded
- Pins
- Not recorded
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: TVS or ESD protection diode.
SMF33A-MFLTVS diode, Formosa MicrosemiTVS diodeFormosa Microsemi
- What it is
- TVS diode
- Maker
- Formosa Microsemi
- Package
- Not recorded
- Pins
- Not recorded
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: TVS or ESD protection diode.
SMF33A-MSTVS diode, Formosa MicrosemiTVS diodeFormosa Microsemi
- What it is
- TVS diode
- Maker
- Formosa Microsemi
- Package
- Not recorded
- Pins
- Not recorded
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: TVS or ESD protection diode.
SMF33A-MS-Q1TVS diode, Formosa MicrosemiTVS diodeFormosa Microsemi
- What it is
- TVS diode
- Maker
- Formosa Microsemi
- Package
- Not recorded
- Pins
- Not recorded
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: TVS or ESD protection diode.
74AUP2G04FW3Diodes IncorporatedNot recordedDiodes Incorporated
- What it is
- Not recorded
- Maker
- Diodes Incorporated
- Package
- Not recorded
- Pins
- Not recorded
- Details
- CMOS logic IC: Dual inverter
- Source
- Published code list
Is it dead? The meter test is below: Integrated circuit.
BD49L44GVoltage supervisor, ROHMVoltage supervisorROHM
- What it is
- Voltage supervisor
- Maker
- ROHM
- Package
- Not recorded
- Pins
- Not recorded
- Details
- Voltage Detector
- Source
- Published code list
Is it dead? The meter test is below: Integrated circuit.
BD52E34G-MVoltage supervisor, ROHMVoltage supervisorROHM
- What it is
- Voltage supervisor
- Maker
- ROHM
- Package
- Not recorded
- Pins
- Not recorded
- Details
- Voltage detector IC: 3.4V±1%, -Reset ODO
- 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.
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.
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.
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.
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.
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.
Codes that begin with MM
For a marking with its end worn or burnt off. Each code has a page of its own.
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