# 1N4148

**Diodes Incorporated** · Small-signal switching diode · DO-35

The 1N4148 is the standard small-signal fast switching diode, in the axial DO-35 glass package, one of the most-used diodes ever made. It blocks 100 V, passes up to 300 mA, and recovers in about 4 nanoseconds, which is what makes it fast enough for logic, clamping, small rectification, steering, and flyback snubbing on tiny loads. It is the through-hole version of the surface-mount 1N4148W (SOD-123). The banded end is the cathode (pin 1).

## Pinout

| Pin | Name | Type | Function |
|---|---|---|---|
| 1 | K | passive | Cathode terminal of the diode, identified by the printed band on the glass body (Polarity: Cathode Band). Blocks reverse current up to VR = 75V DC (VRM = 100V non-repetitive). |
| 2 | A | passive | Anode terminal of the diode. Conventional forward current flows into this lead toward the cathode; VF typ 0.62V min to 1.0V max at IF = 10mA (1N4148). |

## Key specifications

| Parameter | Value |
|---|---|
| Type | Fast switching diode |
| Reverse voltage (VRRM) | 100 V |
| Forward current (IF avg) | 300 mA |
| Reverse recovery (trr) | 4 ns |
| Forward voltage (VF) | ~0.72 V at 10 mA |
| Peak surge (IFSM) | 2 A |
| Marking | band = cathode (pin 1) |
| Package | DO-35 (axial glass) |

## Ordering variants

- `1N4148-T (DO-35)`
- `1N4148TR (DO-35, tape & reel)`

## CAD (KiCad official)

- Symbol: `Diode:1N4148`
- Footprint: `Diode_THT:D_DO-35_SOD27_P7.62mm_Horizontal`
- 3D model: DO-35 (KiCad packages3D)

## Provenance

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

- **Datasheet:** [Diodes Incorporated datasheet](https://www.diodes.com/assets/Datasheets/ds12019.pdf) (2 pp, sha256 `5549ceb4097e1393`, retrieved 2026-08-17, tier: manufacturer)
- **Extractor:** `ds2sf` (Claude). Every pin and dimension is cited to a datasheet page; it refuses to fabricate.
- **CAD:** KiCad official libraries (CC-BY-SA 4.0).

[Datasheet PDF](docs/1n4148-datasheet.pdf)