SMD code WMs
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.
The last letter, s, is lower case, which on NXP and Philips parts is a date or factory code, so it was set aside and WM was searched.
146 parts are printed WMs
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.
BZT52C16-FSOD-123FZener diode, 2 pins, Taitron ComponentsZener diodeSOD-123F2 pinsTaitron Components
- What it is
- Zener diode
- Maker
- Taitron Components
- Package
- SOD-123F
- Pins
- 2
- Details
- Zener diode: 15.3..17.1V, Izt=5mA, 410mW
- Source
- Published code list
Is it dead? The meter test is below: Zener diode.
BZT52C16-VSOD-123Zener diode, 2 pins, VishayZener diodeSOD-1232 pinsVishay
- What it is
- Zener diode
- Maker
- Vishay
- Package
- SOD-123
- Pins
- 2
- Details
- Zener diode: 16V±5%, Izt=5mA, Zzt=40, 500mW
- Source
- Published code list
Is it dead? The meter test is below: Zener diode.
BZT52C20-GSOD-123Zener diode, 2 pins, Taiwan SemiconductorZener diodeSOD-1232 pinsTaiwan Semiconductor
- What it is
- Zener diode
- Maker
- Taiwan Semiconductor
- Package
- SOD-123
- Pins
- 2
- Details
- 5220 V Zener diode
- Source
- Published code list
Is it dead? The meter test is below: Zener diode.
BZT52C20TSOD-523Zener diode, 2 pins, Diodes IncorporatedZener diodeSOD-5232 pinsDiodes Incorporated
- What it is
- Zener diode
- Maker
- Diodes Incorporated
- Package
- SOD-523
- Pins
- 2
- Details
- Z-diode: 20V±5%, Izt=5mA, Zzt=55Ω, 150mW
- Source
- Published code list
Is it dead? The meter test is below: Zener diode.
BZX84-C16SOT-23Zener diode, 3 pins, Won-Top ElectronicsZener diodeSOT-233 pinsWon-Top Electronics
- What it is
- Zener diode
- Maker
- Won-Top Electronics
- Package
- SOT-23
- Pins
- 3
- Details
- 16 V approx. ±5% voltage regulator (Zener) diode
- Source
- Published code list
Is it dead? The meter test is below: Zener diode.
BZX84-C16WSOT-3233 pins, Micro Commercial ComponentsNot recordedSOT-3233 pinsMicro Commercial Components
- What it is
- Not recorded
- Maker
- Micro Commercial Components
- Package
- SOT-323
- Pins
- 3
- Details
- Z-diode: 16V±5%, 200mW
- Source
- Published code list
Is it dead? The meter test is below: Silicon diode.
BZX84B16SOT-23Zener diode, 3 pins, PanjitZener diodeSOT-233 pinsPanjit
- What it is
- Zener diode
- Maker
- Panjit
- Package
- SOT-23
- Pins
- 3
- Source
- Published code list
Is it dead? The meter test is below: Zener diode.
BZX384-C16SOD-323Zener diode, 2 pins, VishayZener diodeSOD-3232 pinsVishay
- What it is
- Zener diode
- Maker
- Vishay
- Package
- SOD-323
- Pins
- 2
- Source
- Published code list
Is it dead? The meter test is below: Zener diode.
BZX384B16SOD-323Zener diode, 2 pins, VishayZener diodeSOD-3232 pinsVishay
- What it is
- Zener diode
- Maker
- Vishay
- Package
- SOD-323
- Pins
- 2
- Source
- An older or alternative marking, from a published code list
Is it dead? The meter test is below: Zener diode.
BZX384C16-FSOD-323Zener diode, 2 pins, Taitron ComponentsZener diodeSOD-3232 pinsTaitron Components
- What it is
- Zener diode
- Maker
- Taitron Components
- Package
- SOD-323
- Pins
- 2
- Details
- Zener diode: 15.3..17.1V, Izt=5.0mA, 200mW
- Source
- Published code list
Is it dead? The meter test is below: Zener diode.
BZX384C16-VSOD-323Zener diode, 2 pins, VishayZener diodeSOD-3232 pinsVishay
- What it is
- Zener diode
- Maker
- Vishay
- Package
- SOD-323
- Pins
- 2
- Details
- Zener diode: 16V±5%, Izt=5mA, Zzt=10, 200mW
- Source
- Published code list
Is it dead? The meter test is below: Zener diode.
BZX784C16SOD-723Zener diode, 2 pins, PanjitZener diodeSOD-7232 pinsPanjit
- What it is
- Zener diode
- Maker
- Panjit
- Package
- SOD-723
- Pins
- 2
- Source
- Published code list
Is it dead? The meter test is below: Zener diode.
CD214A-T64CASMATVS diode, 2 pins, BournsTVS diodeSMA2 pinsBourns
- What it is
- TVS diode
- Maker
- Bourns
- Package
- SMA
- Pins
- 2
- Details
- TVS: 64V, 3.9A, 400W(1ms), Bidirectional
- Source
- Published code list
Is it dead? The meter test is below: TVS or ESD protection diode.
CZRW55C20-GSOD-123Zener diode, 2 pins, ComchipZener diodeSOD-1232 pinsComchip
- What it is
- Zener diode
- Maker
- Comchip
- Package
- SOD-123
- Pins
- 2
- Details
- Zener diode: 20.0..21.20V, Zzt=55, Izt=5mA, 500mW
- Source
- Published code list
Is it dead? The meter test is below: Zener diode.
EC76SMAJ7.0CASMATVS diode, 2 pins, E-CMOSTVS diodeSMA2 pinsE-CMOS
- What it is
- TVS diode
- Maker
- E-CMOS
- Package
- SMA
- Pins
- 2
- Details
- Transient voltage supressor: Vbr=7.78..8.60V, Vrwm=7.0V, Ipp=33.3A, 400W(1ms), Bidir.
- Source
- Published code list
Is it dead? The meter test is below: TVS or ESD protection 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.
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.
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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