# SI2318A

**UMW** · MOSFETs · SOT-23

SI2318A from UMW, in a SOT-23. 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 | G | input | GATE terminal of the 40V N-channel MOSFET; gate-source voltage is rated ±20 V (VGS) per the absolute maximum ratings. |
| 2 | S | passive | SOURCE terminal of the N-channel MOSFET, the reference for gate-source voltage and the source of the body diode (IS 23 A, ISM 14 A per the electrical characteristics table). |
| 3 | D | passive | DRAIN terminal of the N-channel MOSFET; drain-source voltage is rated 40 V (VDS) and continuous drain current 5.6 A at TC=25°C per the absolute maximum ratings. |

## Key specifications

| Parameter | Value |
|---|---|
| Manufacturer | UMW |
| Package | SOT-23 |
| Category | Transistors/Thyristors |
| 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 |
|---|---|---|---|---|---|---|---|
| Drain-Source Voltage | VDS |  |  | 40 | V |  | 1 |
| Gate-Source Voltage | VGS | -20 |  | 20 | V |  | 1 |
| Continuous Drain Current | ID |  |  | 5.6 | A | TC=25°C | 1 |
| Continuous Drain Current | ID |  |  | 4.5 | A | TC=70°C | 1 |
| Continuous Drain Current | ID |  |  | 4.3 | A | TA=25°C, surface mounted on 1in x 1in FR4, t=5 s (notes b,c) | 1 |
| Continuous Drain Current | ID |  |  | 3.5 | A | TA=70°C, surface mounted on 1in x 1in FR4, t=5 s (notes b,c) | 1 |
| Pulsed Drain Current | IDM |  |  | 20 | A |  | 1 |
| Power Dissipation | PD |  |  | 2.1 | W | TC=25°C | 1 |
| Power Dissipation | PD |  |  | 1.3 | W | TC=70°C | 1 |
| Power Dissipation | PD |  |  | 1.25 | W | TA=25°C, surface mounted on 1in x 1in FR4, t=5 s (notes b,c) | 1 |
| Power Dissipation | PD |  |  | 0.8 | W | TA=70°C, surface mounted on 1in x 1in FR4, t=5 s (notes b,c) | 1 |
| Junction Temperature | TJ |  |  | 150 | °C |  | 2 |
| Storage Temperature Range | TSTG | -55 |  | 150 | °C |  | 2 |
| Thermal Resistance, Junction-to-Ambient | RthJA |  |  | 100 | °C/W | Surface mounted on 1in x 1in FR4, t=5 s (notes b,c) | 2 |
| Thermal Resistance, Junction-to-Ambient (steady state) | RthJA |  |  | 130 | °C/W | Maximum under steady state conditions (note d) | 2 |
| Thermal Resistance, Junction-to-Foot | RthJF |  |  | 60 | °C/W |  | 2 |
| Drain-Source Breakdown Voltage | VDSS | 40 |  |  | V | ID=250µA, VGS=0V | 3 |
| Zero Gate Voltage Drain Current | IDSS |  |  | 1 | µA | VDS=40V, VGS=0V | 3 |
| Zero Gate Voltage Drain Current | IDSS |  |  | 10 | µA | VDS=10V, VGS=0V, TJ=70°C | 3 |
| Gate-Body Leakage Current | IGSS | -100 |  | 100 | nA | VDS=0V, VGS=±20V | 3 |
| Gate Threshold Voltage | VGS(th) | 1.2 |  | 2.5 | V | VDS=VGS, ID=250µA | 3 |
| On State Drain Current | ID(ON) | 20 |  |  | A | VGS=10V, VDS≥5V | 3 |
| Static Drain-Source On-Resistance | RDS(ON) |  |  | 36 | mΩ | VGS=10V, ID=4.7A | 3 |
| Static Drain-Source On-Resistance | RDS(ON) |  |  | 46 | mΩ | VGS=4.5V, ID=3.9A | 3 |
| Diode Forward Voltage | VSD |  |  | 1.2 | V | IS=3.5A, VGS=0V | 4 |

## CAD (KiCad official)

- Symbol: `SI2318A`
- Footprint: `Package_TO_SOT_SMD:SOT-23`
- 3D model: SOT-23 (KiCad packages3D, STEP)
- 3D model files: `si2318a-etched.step` / `si2318a-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `si2318a.step` / `si2318a.glb` are the bare package body.

## Provenance

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

- **Datasheet:** [UMW datasheet](https://jlcpcb.com/api/file/downloadByFileSystemAccessId/8757271667708448768) (10 pp, sha256 `a8729e97d7553a80`, retrieved 2026-10-09, tier: lcsc)
- **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:** KiCad official libraries (CC-BY-SA 4.0).

[Datasheet PDF](docs/si2318a-datasheet.pdf)