# BZX8450-C3V9-QR

**Nexperia** · Zener Diodes · TO-236AB

BZX8450-C3V9-QR from Nexperia, in a TO-236AB. Pinout and pin descriptions extracted from the manufacturer datasheet (extract_pins, cross-checked by a second model). Symbol and footprint from KiCad-official CAD; the 3D model is generated from the datasheet's package dimensions.

## Pinout

| Pin | Name | Type | Function |
|---|---|---|---|
| 1 | A | passive | Anode of the low-current voltage regulator diode; the datasheet gives no separate electrical limit for this pin. |
| 2 | n.c. | unconnected | Pin 2 is not connected internally and is not used in the circuit. |
| 3 | K | passive | Cathode of the low-current voltage regulator diode; the cathode tab is the soldering point referenced for thermal resistance junction-to-solder point (Rth(j-sp) 330 K/W max). |

## Key specifications

| Parameter | Value |
|---|---|
| Manufacturer | Nexperia |
| Package | TO-236AB |
| Category | Diodes |
| Pins | 3 |

## Electrical characteristics

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

| Parameter | Symbol | Min | Typ | Max | Unit | Conditions | Page |
|---|---|---|---|---|---|---|---|
| Working voltage (BZX8450-C3V9-Q) | VZ | 3.7 |  | 4.1 | V | Tj = 25 °C | 4 |
| Temperature coefficient (BZX8450-C3V9-Q) | SZ | -2.7 |  | 2.5 | mV/K | Tj = 25 °C | 4 |
| Differential resistance (BZX8450-C3V9-Q) | rdiff |  |  | 600 | Ω | IZ = 50 µA; Tj = 25 °C | 4 |
| Differential resistance (BZX8450-C3V9-Q) | rdiff |  |  | 95 | Ω | IZ = 1 mA; Tj = 25 °C | 4 |
| Differential resistance (BZX8450-C3V9-Q) | rdiff |  |  | 5 | Ω | IZ = 5 mA; Tj = 25 °C | 4 |
| Diode capacitance (BZX8450-C3V9-Q) | Cd |  |  | 150 | pF | f = 1 MHz; VR = 0 V | 4 |
| Forward voltage | VF |  |  | 0.9 | V | IF = 10 mA; pulse test tp ≤ 300 µs; δ ≤ 0.02 | 4 |
| Working voltage tolerance series (approximate) |  | -5 |  | 5 | % | approximately ±5 %, series tolerance as stated in Features | 1 |
| Forward current | IF |  |  | 200 | mA |  | 3 |
| Non-repetitive peak reverse power dissipation | PZSM |  |  | 40 | W | tp = 100 µs; square wave; Tj = 25 °C; prior to surge | 3 |
| Total power dissipation | Ptot |  |  | 250 | mW | Tamb ≤ 25 °C; device mounted on FR4 PCB, single sided copper, tin-plated, standard footprint | 3 |
| Junction temperature | Tj |  |  | 150 | °C |  | 3 |
| Ambient temperature | Tamb | -55 |  | 150 | °C |  | 3 |
| Storage temperature | Tstg | -65 |  | 150 | °C |  | 3 |
| Thermal resistance from junction to ambient | Rth(j-a) |  |  | 500 | K/W | in free air; device mounted on FR4 PCB, single sided copper, tin-plated, standard footprint | 3 |
| Thermal resistance from junction to solder point | Rth(j-sp) |  |  | 330 | K/W | soldering point of cathode tab | 3 |

## CAD (land: KiCad; 3D: generated from the datasheet)

- Symbol: `BZX8450-C3V9-QR`
- Footprint: `Package_TO_SOT_SMD:SOT-23`
- 3D model: TO-236AB, generated on the KiCad land (body 1.3 x 2.9 mm, terminals on the pads, 1.0 mm tall, datasheet A, midpoint of min and max). KiCad's stock model for this land is taller than the datasheet allows, so the model is generated from the datasheet drawing; the dimensions come from the datasheet drawing where it was read and are defaults otherwise (see provenance.model_3d_generated), not the manufacturer's CAD (STEP)
- 3D model files: `bzx8450-c3v9-qr-etched.step` / `bzx8450-c3v9-qr-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `bzx8450-c3v9-qr.step` / `bzx8450-c3v9-qr.glb` are the bare package body.

## Provenance

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

- **Datasheet:** [Nexperia datasheet](https://assets.nexperia.com/documents/data-sheet/BZX8450-C3V9-QR.pdf) (10 pp, sha256 `c4eaf3bb5a88aca0`, retrieved 2026-11-12, tier: manufacturer)
- **Extractor:** parts-factory `2.0.0` / `extract_pins 0.3`, primary `claude-haiku-5-5` (text), consensus `claude-sonnet-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:** land: KiCad official libraries (CC-BY-SA 4.0); 3D: generated from the datasheet's package dimensions (provenance.model_3d_generated).

[Datasheet PDF](docs/bzx8450-c3v9-qr-datasheet.pdf)