component
MMSZ5257B
Public Made by Adomby adom
MSKSEMI Zener Diodes, SOD-123. Pinout cross-checked by two models against the datasheet, KiCad symbol/footprint/3D.
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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.glbcarry the MPN laser-etched on the die in a toggleableAdom.LaserEtchgroup (Fusion-ready);mmsz5257b.step/mmsz5257b.glbare 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, primaryclaude-sonnet-5-5(text+vision), consensusclaude-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).
# 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](https://jlcpcb.com/api/file/downloadByFileSystemAccessId/8590456137469628416) (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](docs/mmsz5257b-datasheet.pdf)