Overview

The 1N4001 is a standard 1.0 Amp general-purpose silicon rectifier diode IC manufactured by ON Semiconductor, Vishay, and Diodes Incorporated. Bundled in almost every electronic components starter kit, it is used for AC-to-DC mains rectification, reverse polarity input protection, and flyback diode protection across inductive relay and motor coils.

Housed in a black plastic DO-41 axial package with a silver cathode band marking, the 1N4001 is rated for a peak repetitive reverse voltage (VRRMV_{RRM}) of 50 Volts50\text{ Volts} and an average forward rectified current (IF(AV)I_{F(AV)}) of 1.0 Ampere1.0\text{ Ampere}.

Quick reference

Diode TypeSilicon Junction Power Rectifier Diode
PackageDO-41 (DO-204AL) Axial Package
Polarity MarkingSilver / White Band = Cathode (K), Opposite Lead = Anode (A)
Peak Repetitive Reverse Voltage (VRRMV_{RRM})50 V50\text{ V} max
Average Forward Rectified Current (IF(AV)I_{F(AV)})1.0 A1.0\text{ A} continuous at TA=75∘CT_A = 75^\circ\text{C}
Peak Forward Surge Current (IFSMI_{FSM})30 A30\text{ A} (8.3ms half sine-wave surge)
Forward Voltage Drop (VFV_F)1.0 V1.0\text{ V} max at IF=1.0AI_F = 1.0\text{A} (0.7V…0.8V0.7\text{V} \dots 0.8\text{V} typical)
Reverse Leakage Current (IRI_R)5.0 μA5.0\ \mu\text{A} max at VR=50VV_R = 50\text{V}

Pinout (Axial DO-41 Package)

text
        (Anode) ───[ BLACK CYLINDER ]═══(Cathode Silver Band)───
                      1N4001
LeadNameDescription
Anode (A)Plain LeadPositive current entry lead
Cathode (K / C)Silver Band LeadNegative current exit lead (marked by silver/white stripe)

1N400x Diode Series Comparison Table

The 1N4001 is the 50V50\text{V} rated entry in the 1N400x family. All 1N400x diodes share the same 1.0A current rating:

Part NumberPeak Repetitive Reverse Voltage (VRRMV_{RRM})RMS Voltage (VRMSV_{RMS})
1N400150 V50\text{ V}35 V35\text{ V}
1N4002100 V100\text{ V}70 V70\text{ V}
1N4003200 V200\text{ V}140 V140\text{ V}
1N4004400 V400\text{ V}280 V280\text{ V}
1N4005600 V600\text{ V}420 V420\text{ V}
1N4006800 V800\text{ V}560 V560\text{ V}
1N40071000 V1000\text{ V}700 V700\text{ V}

Common Applications

Inductive Flyback Protection Diode

When driving a relay coil or solenoid with a transistor, place a 1N4001 diode in parallel across the coil with Cathode connected to +VCC+V_{CC} and Anode to the transistor Collector:

text
        +12V Supply Rail ──────┬───────────────────────────┐
                               │                           │
                   [ 12V Relay Coil ]            [ 1N4001 Cathode ] (Silver Band)
                               │                           │
                               ├───────────────────────────┘
                               │
                       [ 2N2222 Collector ]

Reverse Polarity Power Protection

Place a 1N4001 in series with the +VCC+V_{CC} power input lead (Anode to Power Input, Cathode to Circuit VCCV_{CC}) to prevent reverse battery connection from damaging sensitive electronics.

Common mistakes

  • Installing diode in reverse polarity: Connecting Cathode to Anode blocks forward current completely. Always identify the silver band marking the Cathode.
  • Using 1N4001 in high-frequency SMPS (>10kHz): 1N4001 is a slow standard recovery rectifier (trr>30 μst_{rr} > 30\ \mu\text{s}). In high-frequency switching power supplies (like 150kHz buck converters), slow recovery diodes overheat. Use a fast Schottky diode (e.g. 1N5819, SS14, or SS34).

Notes

  • 1N4001 vs 1N4007 vs 1N4148: 1N4001 is a 50V 1A power rectifier; 1N4007 is a 1000V 1A power rectifier; 1N4148 is a 100V 300mA high-speed small-signal switching diode.

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