Transcript Diode Specifications for Power Applications

The semiconductor power diode has
been used extensively in various power
applications such as power rectifiers
and power supplies
Diodes
Since the invention of semiconductor materials and the eventually birth of the
modern day power diode, its usefulness has become apparent to engineers and
other electrical designers. As new technology is improving efficiencies and
versatility, engineers are finding more ways to use the power diode than ever
before.
Outline
 What is a Power Diode?
 Sample Power Diodes
 Schottky Diode
 Applications of Power Diodes
 Rectifiers
 Power Conversion
 Current Steering (Power Supplies)
Power Diodes
 A power diode is a crystalline semiconductor device, made
primarily of silicon, used mainly to convert alternating
current (AC) to direct current (DC), a process known as
rectification.
 Power Diodes work as a one way valve, by conducting
current in one direction (the forward direction) while
preventing flow in the other direction.
 Best used in high voltage/high current applications due to
their large P-N Junctions & high current carrying capacity.
 Sample Specs given on following slide from the BYC8-600
Hyperfast Power Diode from NXP Semiconductor
Schottky Diodes
 The Schottky Diode is a metal–semiconductor whose
junction is formed between a metal and a semiconductor,
creating a Schottky barrier (instead of a semiconductor–
semiconductor junction as in conventional diodes)
 They are suitable for low voltage very high frequency
switching power supply applications
 Low Forward Voltage Drop (.15-.45V at 1mA)
 Low Junction Capacitance (C) providing high switching
speeds.
Rectifiers
 Used primarily to convert AC to DC.
 Implemented in high voltage direct current power
transmission systems.
 For power rectification from very low to very high current,
semiconductor diodes of various types ( Schottky diodes,
etc.) are widely used.
Power Conversion
 Rectifiers are constructed from diodes, where they are
used to convert alternating current (AC) electricity into
direct current (DC). Automotive alternators are a common
example, where the diode, which rectifies the AC into DC,
provides better performance than the commutator or
earlier, dynamo.
Current Steering
 Using diodes, you can prevent current from flowing in
unwanted directions.
 A power supply can use this to ensure that power is only
drawn from a battery when necessary.
 In automotive use, a heavy-duty split-charge diode is used
to prevent the engine battery from discharging through
the lower-charge battery when the alternator is not
running.
Conclusion
 Power Diodes have a multitude of uses in power
applications.
 The Shottky Diode is a common power diode.
 Rectifiers use power conversion for converting AC to DC in
most high power applications.
 Current steering can be used from laptop power supplies
to automotive applications.
References
 Donald Neaman, (2003) ”Semiconductor Physics & Devices",
pp.331 – 333
 Anonymous. Schottky_diode_symbol.svg. Wikipedia.
http://en.wikipedia.org/wiki/File:Schottky_diode_symbol.svg
 Anonymous. Rectifier.jpg. Wikipedia.
http://en.wikipedia.org/wiki/Rectifier
 Shimada, N. “High-Power 625-nm AlGaInP Laser Diode”. Dec
2011.
 NXP Semiconductors.
“http://www.nxp.com/products/diodes/power_diodes_hyperfas
t_recovery/”
Concepts
 What is a Power Diode…
 Primary uses of a Power Diode
 Schottky Diodes
 Power Conversion
 Current Steering