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SMD code U8 in SOD-523

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.

6 parts in SOD-523 are printed U8

Not sure which one you have?

Answer up to 4 quick questions and these 35 parts are ranked, with a meter test that settles it. It works on a dead part too.

  • BZX584C18SOD-523Zener diode, Blue RocketZener diodeBlue Rocket
    What it is
    Zener diode
    Maker
    Blue Rocket
    Package
    SOD-523
    Pins
    2
    Source
    Manufacturer datasheet

    Is it dead? The meter test is below: Zener diode.

    Datasheetfor BZX584C18, opens in a new tab
  • MM5Z18SOD-523Zener diode, YFWZener diodeYFW
    What it is
    Zener diode
    Maker
    YFW
    Package
    SOD-523
    Pins
    2
    Details
    Zener diode, 10 V, 0.01 A
    Source
    Manufacturer datasheet

    Is it dead? The meter test is below: Zener diode.

    Datasheetfor MM5Z18, opens in a new tab
  • MM5Z18BSOD-523Zener diode, RectronZener diodeRectron
    What it is
    Zener diode
    Maker
    Rectron
    Package
    SOD-523
    Pins
    2
    Source
    Manufacturer datasheet

    Is it dead? The meter test is below: Zener diode.

    Datasheetfor MM5Z18B, opens in a new tab
  • MM5Z18VSOD-523Zener diode, Formosa MicrosemiZener diodeFormosa Microsemi
    What it is
    Zener diode
    Maker
    Formosa Microsemi
    Package
    SOD-523
    Pins
    2
    Source
    Manufacturer datasheet

    Is it dead? The meter test is below: Zener diode.

    Datasheetfor MM5Z18V, opens in a new tab
  • BZT52C18WTSOD-523Zener diode, Taitron ComponentsZener diodeTaitron Components
    What it is
    Zener diode
    Maker
    Taitron Components
    Package
    SOD-523
    Pins
    2
    Details
    SMD Zener Diodes (Two Terminals) - 200mW
    Source
    An older or alternative marking, from a published code list

    Is it dead? The meter test is below: Zener diode.

    Datasheetfor BZT52C18WT, opens in a new tab
  • MM5Z18HSOD-523Zener diode, Zowie TechnologyZener diodeZowie Technology
    What it is
    Zener diode
    Maker
    Zowie Technology
    Package
    SOD-523
    Pins
    2
    Details
    Zener diode: 16.8..19.1V, Izt=2mA, Zzt=45, 200mW
    Source
    Published code list

    Is it dead? The meter test is below: Zener diode.

  • 9 more parts have no package on record. Nothing rules them out, so they stay.

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.

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.

Printed with a code easy to misread as U8

One character differs, and it is one that is easy to confuse under a lamp. 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.