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SMD code SQ

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.

2 parts are printed SQ

Not sure which one you have?

Answer up to 4 quick questions and these 2 parts are ranked, with a meter test that settles it. It works on a dead part too.

Schottky diode. What differs:

  • B0540WFSOD-123F2 pins, Taiwan Semiconductor
    What it is
    Schottky diode
    Maker
    Taiwan Semiconductor
    Package
    SOD-123F
    Pins
    2
    Source
    From the manufacturer's datasheet

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

    Datasheetfor B0540WF, opens in a new tab
  • SDM0520SSOT-233 pins, Diotec
    What it is
    Schottky diode
    Maker
    Diotec
    Package
    SOT-23
    Pins
    3
    Details
    SMD Small Signal Schottky Diodes
    Source
    From the manufacturer's datasheet

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

    Datasheetfor SDM0520S, opens in a new tab

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.

Printed with a code easy to misread as SQ

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 SQ

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 30 more parts.

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