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SMD code 950 in SOT-353

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.

1 part in SOT-353 is printed 950

Not sure which one you have?

Answer up to 4 quick questions and these 3 parts are ranked, with a meter test that settles it. It works on a dead part too.

  • LN1121P311KRSOT-353LDO regulator, Shanghai Natlinear ElectronicsLDO regulatorShanghai Natlinear Electronics
    What it is
    LDO regulator
    Maker
    Shanghai Natlinear Electronics
    Package
    SOT-353
    Pins
    5
    Details
    Linear voltage regulator IC: LDO, 3.1V±2%, 250mA
    Source
    Published code list

    Is it dead? The meter test is below: Voltage regulator.

  • 2 more parts have no package on record. Nothing rules them out, so they stay.
    • 1PMT5950BZener diode, Microsemi Integrated Products DivisionZener diodeMicrosemi Integrated Products Division
      What it is
      Zener diode
      Maker
      Microsemi Integrated Products Division
      Package
      Not recorded
      Pins
      Not recorded
      Details
      Zener diode: 91V±5%, Izt=16mA, 2.5W
      Source
      Published code list

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

    • LN1121P312VRLDO regulator, Shanghai Natlinear ElectronicsLDO regulatorShanghai Natlinear Electronics
      What it is
      LDO regulator
      Maker
      Shanghai Natlinear Electronics
      Package
      Not recorded
      Pins
      Not recorded
      Details
      Linear voltage regulator IC: LDO, 3.1V±2%, 250mA
      Source
      Published code list

      Is it dead? The meter test is below: Voltage regulator.

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.

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.

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 950

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 950

For a marking with its end worn or burnt off. Each code has a page of its own.

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