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 (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