1N5408 Power Diode : Pin Configuration & Its Applications

The 1n5408 power diode is a two-terminal component namely anode and cathode. The flow of current in this diode is simply in one direction from the terminal’s anode to the cathode, so it is considered as an electronic check valve. This diode carries less resistance within one way whereas extremely high resistance within the remaining direction.


As the name suggests, this diode carries maximum repetitive reverse voltage & forward current. It is used in circuits that operate below 3A. This article discusses an overview of 1N5408 power diode, pin configuration, and its applications

What is 1N5408 Power Diode?

1N5408 is one kind of power diode from the 1N540x series. This general-purpose dode includes several features so that it can be used in an extensive range of applications. This kind of diode is capable of handling up to 3000mA/3A of current beyond it and it is available in the DO201 package, but it is somewhat superior to the DO-41 package. This diode replaces DO-41 if a little larger space is obtainable.

This diode is suitable if you are searching for a diode that handles a bit more ampere current as compared to DO-41 type like 1N4148, 1N4007, etc. These diodes can be replaced with a 1N5408 power diode in most of the applications to achieve more forward current.

1N5408 Power Diode
1N5408 Power Diode

This diode turns outmoded within the current electronic circuits because of the slow recovery time. This diode is being substituted by superior & maximum efficient types of diodes. The VI characteristics of the 1N5408 power diode are non-linear. In addition, it allows the flow of current only in a single direction once the fixes threshold voltage is attained within the forward direction.

Pin Configuration

The pin configuration of the 1N5408 power diode is shown below. This power diode includes two terminals where each terminal functionality is discussed below.

1N5408 Diode Pin Configuration
1N5408 Diode Pin Configuration
  • Pin1 (Anode): This terminal is used to allow the flow of current
  • Pin2 (Cathode): The flow of current will be exit through this terminal

Features & Specifications

The features and specifications of the 1N5408 power diode include the following.

PCBWay
  • Available in small size
  • It has a maximum capacity of surge current
  • A low forward drop of voltage
  • Accessible within volume quantity
  • Forward current (Avg) is 3A
  • A forward drop of voltage is 1V at 3A
  • Max non-repetitive current is 200A
  • Max reverse current is 10uA.
  • Cyclic reverse voltage is 1000V
  • Accessible within DO-201 Package
  • Rectifier Diode type used in general purpose applications
  • Reverse current max is 10uA
  • Non-repetitive fwd current max is 200A
  • Max operating & storage temperature ranges from -65 Centigrade to +175 Centigrade

Alternative 1N5408 power diodes are 1N5400, 401, 402, 404, 406 & 407. The equivalent 1N5408 power diodes are CR3-100, P300M, CR3-120, FR307, G3M, FR607, V3510 & HER508. The main disparity between these two diodes is the PRRV (Peak repetitive reverse voltage) & RPRV (Nonrepetitive reverse voltage) however the circuits must use in between 12V-24V then there is no issue. If you are using more than 12V-24V then you should verify their PRRV and RPRV & you should choose maximum PRRV as compared to the operating voltage.

How to Long Run this Diode within a Circuit?

The following precautions need to take to safely run this diode for a long time in different applications.

  • This diode can be used in different circuits, devices, and projects for a long time which operates >1000V
  • To obtain superior performance always stay under the maximum characteristics or specification values.
  • Should not drive or operate load above 3A beyond this diode
  • Store & operate this diode in < -65 centigrade temperature & < +175 centigrade.

How to use 1N5408 Power Diode/ Circuit Diagram

The reverse polarity protection circuit using a 1N5408 power diode is shown below. If you fix your MST & DDS VFO toward a power supply through the incorrect polarity then the circuit will blow. So to protect the circuit from reverse polarity the following method is used In this technique, a diode and a fuse is used within the circuit as illustrated below.

OurPCB
Reverse Polarity Protection Circuit with 1N5408 Diode
Reverse Polarity Protection Circuit with 1N5408 Diode

Once the polarity of the power supply is accurate then the 1N5408 power diode is connected in reverse bias & which does not work. But if the polarity is connected in reverse, then this diode performs & restricts the reverse voltage beyond the MST to approximately 0.8V.

If the power supply within the circuit provides above 2 Amps then the fuse within the circuit will be damaged & the power supply will be disconnect completely. This circuit is very simple however effective to use. The only disadvantage is that you need an alternate fuse to replace it with a damaged one in the circuit. The 1N5408 power diode is strong so it will resist the current from the short circuit until the fuse in the circuit damages.


  • Fix a fuse holder like the M205 holder over the rear panel which is near to the input connectors of the power supply.
  • Wire the +ve power supply connector toward the supply face of the fuse holder.
  • Connect the fuse holder’s load face toward the MST PCB.
  • Need to solder the power diode in between the load face of the holder & the -ve power supply i/p connector. Here, the end of the cathode terminal goes toward the +ve connector.

Where to use 1N5408 Power Diode/Applications

The applications of 1N5408 power diode include the following.

  • 1N5408 power diode is used to perform rectification within power supplies, battery chargers, voltage boosters, and many more.
  • It is used to block the flow of current in the preferred direction within a circuit,
  • Voltage doublers circuits
  • Current supply regulators
  • Adapters
  • Used as a protection device
  • Circuits for rectification
  • HWRs and FWRs
  • Protection of components
  • HV supplies
  • Voltage current and voltage in any required direction
  • The reverse polarity issue can be resolved

Thus, this is all about an overview of the IN5408 diode datasheet that is mainly designed with maximum forward current & reverse voltage including 6.25W of power dissipation. The max current capacity of this diode is 3A and can resist upto 200A. The slow recovery time of these diodes is low, so it is replaced by other diodes in modern electronics. These power diodes are designed in DO-201 Package & offer 1000V of repetitive reverse voltage. Here is a question for you, what are the advantages of 1N5408 power diode?

Add Comment