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MMSZ5257BQ-7-F

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

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MMSZ5257BQ-7-F

Diodes Incorporated · Zener Diodes · SOD-123

MMSZ5257BQ-7-F from Diodes Incorporated, 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, the terminal marked by the cathode band on the package; it goes positive relative to the anode in Zener breakdown (33V nominal, 31.35V to 34.65V at IZT = 3.8mA for the MMSZ5257B).
2 A passive Anode, the terminal opposite the cathode band; forward voltage is 0.9V at IF = 10mA.

Key specifications

Parameter Value
Manufacturer Diodes Incorporated
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 (Nom 33 V, B-suffix limits) VZ 31.35 33 34.65 V @ IZT = 3.8 mA 2
Maximum Zener impedance ZZT 58 Ω @ IZT = 3.8 mA, f = 1 kHz 2
Maximum Zener impedance (knee) ZZK 700 Ω @ IZK = 0.25 mA 2
Maximum reverse leakage current IR 0.1 µA @ VR = 25 V 2
Power dissipation (note 4) PD 500 mW @ TL = +75°C 2
Power dissipation (note 5) PD 370 mW @ TA = +25°C 2
Thermal resistance, junction to ambient air (note 5) RθJA 338 °C/W Device mounted on FR-4 PCB with 1 inch copper pad layout 2
Thermal resistance, junction to lead (note 4) RΘJL 132 °C/W 2
Operating and storage temperature range TJ, TSTG -65 150 °C 2
Forward voltage VF 0.9 V @ IF = 10 mA 2

Materials and finish

As the datasheet states them (page.json metadata.appearance; the 3D model's colours follow it).

Part Material Colour / plating Datasheet says Page
contacts tin  Terminals: Matte Tin Finish Annealed over Alloy 42 Leadframe (Lead Free Plating). Solderable per MIL-STD-202, Method 208 1

CAD (KiCad official)

  • Symbol: MMSZ5257BQ-7-F
  • Footprint: Diode_SMD:D_SOD-123F
  • 3D model: SOD-123 (KiCad packages3D, STEP)
  • 3D model files: mmsz5257bq-7-f-etched.step / mmsz5257bq-7-f-etched.glb carry the MPN laser-etched on the die in a toggleable Adom.LaserEtch group (Fusion-ready); mmsz5257bq-7-f.step / mmsz5257bq-7-f.glb are the bare package body.

Provenance

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

  • Datasheet: Diodes Incorporated datasheet (5 pp, sha256 7c7ac7a58521db27, retrieved 2026-10-17, 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