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MMSZ5257B

Public Made by Adom

by adom

MSKSEMI Zener Diodes, SOD-123. Pinout cross-checked by two models against the datasheet, KiCad symbol/footprint/3D.

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Made with KiCad 10.0 · needs KiCad 10.0 or later to open · KiCad file format 20260206
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MMSZ5257B

MSKSEMI · Zener Diodes · SOD-123

MMSZ5257B from MSKSEMI, in a SOD-123. Pinout and pin descriptions extracted from the manufacturer datasheet (extract_pins, cross-checked by a second model); symbol, footprint, and 3D from KiCad-official CAD.

Pinout

Pin Name Type Function
1 K passive Cathode (banded end, marked '-' on the package outline); goes positive relative to the anode in reverse Zener breakdown, with VZ of 31.35 V min to 34.65 V max at IZT = 3.8 mA for MMSZ5257B.
2 A passive Anode (marked '+' on the package outline); forward voltage is 0.9 V at IF = 10 mA.

Key specifications

Parameter Value
Manufacturer MSKSEMI
Package SOD-123
Category Diodes
Pins 2

Electrical characteristics

Limits as printed in the datasheet (page.json metadata.characteristics carries them as data).

Parameter Symbol Min Typ Max Unit Conditions Page
Zener voltage VZ (MMSZ5257B, nominal 33 V) VZ 31.35 33 34.65 V IZT=3.8 mA 3
Maximum Zener impedance ZZT ZZT 58 Ω IZT=3.8 mA 3
Maximum Zener impedance ZZK ZZK 700 Ω IZK=0.25 mA 3
Maximum reverse current IR IR 0.1 uA VR=25 V 3
Power dissipation Pd 500 mW Note 1: device mounted on ceramic PCB 7.6 mm x 9.4 mm x 0.87 mm, pad areas 25 mm2 2
Operation junction and storage temperature range TJ,Tstg -55 150 ℃ 2
Forward voltage VF 0.9 V IF = 10mA; Note 2: tested with pulses, Tp≤1.0ms 2
Thermal resistance, junction to ambient air RθJA 357 ℃/W 2

CAD (KiCad official)

  • Symbol: MMSZ5257B
  • Footprint: Diode_SMD:D_SOD-123F
  • 3D model: SOD-123 (KiCad packages3D, STEP)
  • 3D model files: mmsz5257b-etched.step / mmsz5257b-etched.glb carry the MPN laser-etched on the die in a toggleable Adom.LaserEtch group (Fusion-ready); mmsz5257b.step / mmsz5257b.glb are the bare package body.

Provenance

Data extracted from the manufacturer datasheet, not a distributor listing:

  • Datasheet: MSKSEMI datasheet (6 pp, sha256 3baa91984b169107, retrieved 2026-10-19, tier: lcsc)
  • Extractor: parts-factory 2.0.0 / extract_pins 0.3, primary claude-sonnet-5-5 (text+vision), consensus claude-opus-5-5 (agreed), guards: pin_guards 0.1: passed. Pins are checked against the footprint pad set and their cited datasheet pages before publish.
  • CAD: KiCad official libraries (CC-BY-SA 4.0).

Datasheet PDF