component
ZMM5257BST
Public Made by Adomby adom
ST(Semtech) Zener Diodes, LL-34. Unpolarised two-terminal part: the datasheet prints no pin numbers, so pins 1 and 2 follow the library convention, KiCad symbol/footprint/3D.
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ZMM5257BST
ST(Semtech) · Zener Diodes · LL-34
ZMM5257BST from ST(Semtech), in a LL-34. 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 banded/marked end per the datasheet; pad 1 of the KiCad diode footprint. |
| 2 | A | passive | Anode. |
Key specifications
| Parameter | Value |
|---|---|
| Manufacturer | ST(Semtech) |
| Package | LL-34 |
| 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 Min/Max | VZT | 31.35 | 33 | 34.65 | V | at IZT = 3.8 mA, tested with pulses tp = 20 ms | 2 |
| Dynamic Resistance | ZZT | 58 | Ω | at IZT = 3.8 mA | 2 | ||
| Dynamic Resistance (knee) | ZZK | 700 | Ω | at IZK = 0.25 mA | 2 | ||
| Reverse Current | IR | 0.1 | µA | at VR = 25 V | 2 | ||
| Forward Voltage | VF | 1.1 | V | at IF = 200 mA | 1 | ||
| Thermal Resistance Junction to Ambient Air | RthA | 0.3 | K/mW | Valid provided that electrodes are kept at ambient temperature | 1 | ||
| Power Dissipation | Ptot | 500 | mW | Ta = 25 °C, electrodes kept at ambient temperature | 1 | ||
| Junction Temperature | Tj | 175 | °C | Ta = 25 °C | 1 | ||
| Storage Temperature Range | Tstg | -65 | 175 | °C | Ta = 25 °C | 1 | |
| Zener Voltage Tolerance (suffix B) | VZnom | -5 | 5 | % | suffix B | 1 | |
| Nominal Zener Voltage | VZnom | 33 | V | at IZT = 3.8 mA | 2 |
CAD (KiCad official)
- Symbol:
ZMM5257BST - Footprint:
Diode_SMD:D_MiniMELF - 3D model: LL-34 (KiCad packages3D, STEP)
Provenance
Data extracted from the manufacturer datasheet, not a distributor listing:
- Datasheet: ST(Semtech) datasheet (3 pp, sha256
a48a7bc3e88e9776, retrieved 2026-10-22, tier: manufacturer) - Extractor: parts-factory
2.0.0/extract_pins, primarycathode-band convention(convention), consensusoff(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).
# ZMM5257BST
**ST(Semtech)** · Zener Diodes · LL-34
ZMM5257BST from ST(Semtech), in a LL-34. 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 banded/marked end per the datasheet; pad 1 of the KiCad diode footprint. |
| 2 | A | passive | Anode. |
## Key specifications
| Parameter | Value |
|---|---|
| Manufacturer | ST(Semtech) |
| Package | LL-34 |
| 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 Min/Max | VZT | 31.35 | 33 | 34.65 | V | at IZT = 3.8 mA, tested with pulses tp = 20 ms | 2 |
| Dynamic Resistance | ZZT | | | 58 | Ω | at IZT = 3.8 mA | 2 |
| Dynamic Resistance (knee) | ZZK | | | 700 | Ω | at IZK = 0.25 mA | 2 |
| Reverse Current | IR | | | 0.1 | µA | at VR = 25 V | 2 |
| Forward Voltage | VF | | | 1.1 | V | at IF = 200 mA | 1 |
| Thermal Resistance Junction to Ambient Air | RthA | | | 0.3 | K/mW | Valid provided that electrodes are kept at ambient temperature | 1 |
| Power Dissipation | Ptot | | | 500 | mW | Ta = 25 °C, electrodes kept at ambient temperature | 1 |
| Junction Temperature | Tj | | | 175 | °C | Ta = 25 °C | 1 |
| Storage Temperature Range | Tstg | -65 | | 175 | °C | Ta = 25 °C | 1 |
| Zener Voltage Tolerance (suffix B) | VZnom | -5 | | 5 | % | suffix B | 1 |
| Nominal Zener Voltage | VZnom | | 33 | | V | at IZT = 3.8 mA | 2 |
## CAD (KiCad official)
- Symbol: `ZMM5257BST`
- Footprint: `Diode_SMD:D_MiniMELF`
- 3D model: LL-34 (KiCad packages3D, STEP)
## Provenance
Data extracted from the manufacturer datasheet, not a distributor listing:
- **Datasheet:** [ST(Semtech) datasheet](docs/zmm5257bst-datasheet.pdf) (3 pp, sha256 `a48a7bc3e88e9776`, retrieved 2026-10-22, tier: manufacturer)
- **Extractor:** parts-factory `2.0.0` / `extract_pins`, primary `cathode-band convention` (convention), consensus `off` (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/zmm5257bst-datasheet.pdf)