Technology: Microelectronics

First SiC Schottky diode power semiconductors

Pictured: Infineon’s

new SiC Schottky

diode

From April, Inflneon

result in low leakage currents,

However, for conventional

Technologies

low on-resistance

and high cur-

ultra-fast silicon diodes, this

rent densities.Tbis

allows high

method is limited by power

Germany)

(Munich,

will produce

what it

or

claims is the world’s first SiC-

blocking voltages of 300-3,500 V

losses due to reverse recovery

based Schottky diode power

(compared

(which is not exhibited

semiconductors.The

silicon Schottky diodes and up

diodes

will be available in 600 V (4 A andGA)and300V(lOAand 2 x 10 A) versions in TO220 T0263

or

SMT packages.

Compared

to 250 V for GaAs diodes).

with higher voltages in reliable,

sili-

con or GaAs power diodes, SiC

Switched

Mode Power

Supplies (SMPS) with high switching

frequenties

in syç

Schottky diodes allow lower

tems like PCs, servers and

switching

mobile phone base-stations

currents

and losses

Schottky diodes).The return current

This offers new system options compact

to conventional

to about 200 V for

and

must flow

through the switch that is also part of the PFC circuit. Lack of reverse recovery

current

allows

use of a smaller and more cost-effective

MOSFET, removes

this loading from the circuit and increases

overall system

reliability.

and hence higher switching

the increasingly

frequenties

ket of Power Factor Correction

In PFC applications,

(PFC) applications.

losses are determined

mainly

by the diode recovery

current,

resonant snubbers

without

switching

complex circuits

or

as well as heatsinks

and fans.This

allows use of

smaller, cheaper, and fewer passive components), improving

reliability

as well as and lower-

ing system costs. SiC’s characteristics

(higher

In all solutions

growing mar-

in SiC diodes

for active PFC,

there are two approaches: Discontinuous

Current Mode

(DCM) or Continuous

Current

Mode (CCM).

breakdown

with the diode

voltage. Up to now,

this effect limited maximum switching

frequenties

100 kHz without

to below

the use of res

Although CCM requires an ex-

onant snubbers

trcmely fast diode, the highest

power switches. However, the higher the switching

Schottky barrier, bandgap three

currcnts

times that of silicon, ten times

currents, so passive comp0

higher electrical

nents and power switches

breakdown

which increases

switching

are almost half DCM

or auxIliary frequency,

the smaller the number and can

size of the passive components

field strength, and thermal con-

be smaller.Also, a simpler PM1

ductivity compamble

filter can be used and the syç

and the lesser the costs of the

tem is stable even at low load.

whole system.

to copper

and four times that of silicon)

Ill-VS REVIEWTHE ADVANCED SEMICONDUCTOR MAGAZINE VOL14 - NO 2 - MARCH 2001

(such as coils and capacitors),