Manufactured by Vishay Intertechnology, the LL4148 is a small/signal fast switching diode that has silicon epitaxial planar coating. It also has a unidirectional single configuration. Applications that use LL4148 diodes include LED state detection (specifically for the purpose of controlling another circuit) and heat monitoring. 

What is a Diode?

An electrical component or device that functions as a one-way current switch is called a diode. This device only moves a single direction – the starting point is the anode and it goes all the way to the cathode. The anode is also known as positive lead, while the cathode is the negative lead. They are referred to as the polarity of diodes. 

The diode’s one-way path means current that gets in from the other direction is restricted. As such, electrons or current can flow from the negative lead or cathode. However, it cannot flow from the anode to the cathode. 

Another function that a diode performs is to change the AC or alternating current into DC or pulsating direct current.

There are two things that can happen to a diode: reverse-biased and forward-biased. 

  • When current flow is not permitted and the diode functions like an insulator, it is reverse-biased.
  • A forward-biased diode, on the other hand, allows current to flow through.

Vishay Intertechnology’s LL4148 identifies as a cathode band. It is known as a silicon epitaxial planar diode. LL4148 is highly reliable, has 8ns-4ns recovery time, and high conductance, which makes it ideal for exceedingly fast switching.

Diodes come in different configurations: glass case, metal case, plastic case with chamfer, plastic case with band, and stud mount, among others. LL4148 comes in surface mount and through-hole versions, and is packaged in glass to ensure high reliability.  

LL4148 Technical Specifications and Features

  • 500mW power dissipation
  • 500mA peak forward current
  • 100V reverse voltage
  • 62V-1V forward voltage
  • 200mA Average rectified current
  • 25nA @ 20V Reverse leakage current @ Vr
  • 4pF – diode capacitance
  • 175°C junction temperature
  • Weight is 0.05 grams (miniMELF) and 0.13 grams (DO-35)
  • From -65°C - +175°C in storage temperature
  • Case: (SOD-80) MiniMELF (Metal Electrode Leadless Face)

Typical Characteristics


Features of LL4148:

  • Silicon epitaxial planar diode
  • High conductance
  • High reliability
  • Lead-free
  • AEC-Q101 (stress test) qualified – for automotive applications
  • Restriction of Hazardous Substances Directive compliant
  • Identical electrical data with 1N4448 and 1N4148
  • Fast recovery time (8ns-4ns)

The LL4148 is manufactured by Vishay Intertechnology, a global manufacturer of passive electronic components and semiconductors. It is highly popular for its power Metal Oxide Semiconductor Field-Effect Transistors or MOSFETs, which are known for their efficiency and fast switching speed even at low voltage.

Author: Sherly Mendoza
Published: April 15, 2021