MX877R IXYS, MX877R Datasheet - Page 138

• Manufacturer Part Number: MX877R
• Description: IC DVR RELAY/LOAD 8CH 60V 28-QFN
• Manufacturer: IXYS

Specifications of MX877R

• Input Type: Parallel/Serial
• Number Of Outputs: 8
• Current - Output / Channel: 80mA
• Voltage - Supply: 6 V ~ 60 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 28-QFN
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• On-state Resistance: -
• Current - Peak Output: -

Diodes
Diodes for High Switching
Frequencies
Fast
(HiPerFRED, FRED) and FRD (SONIC)
Power switches (IGBT, MOSFET, BJT,
GTO) for applications in electronics are
only as good as their associated free-
wheeling diodes. At increasing switch-
ing frequencies, the proper functioning
and efficiency of the power switch, aside
from conduction losses, is determined
by the turn-off behavior of the diode
(characterized by Q
With optimized ultra-fast switching
diodes, the development engineer has
various possibilities: either higher pul-
se rate or higher current load or smaller
heatsink or more conservative operation
due to „cooler“ chips.
The reverse current characteristic fol-
lowing the peak reverse current I
another very important property. The
slope of the decaying reverse current
di
(technology and diffusion of the diode
chips). In a circuit this current slope, in
conjunction with parasitic inductances
(e.g. connecting leads), causes over-
voltage spikes and high frequency inter-
ference voltages. The higher the dirr/dt
(„hard recovery“ or „snap-off“ behavior)
the higher is the resulting additional
stress for both the diode and the paral-
leled switch. A slow decay of the reverse
current („soft recovery“ behavior), is the
most desirable characteristic, and this is
designed into all diodes. The wide range
of available blocking voltages makes it
possible to apply these diodes as output
rectifiers in switch-mode power supplies
(SMPS) as well as protective and free-
wheeling diodes for power switches in
inverters.
Fig. 2: Cross section of glassivated planar
116
Metallisierung
rr
/dt results from design parameters
epitaxial diode chip with guard rings
(type DWEP)
Metalisation
Recovery
p
n
n
Feldring Guard ring
rr
, I
Epitaxial
RM
Glaspassivierung
and t
rr
- Fig. 1).
Glasspassivation
Diodes
RM
is
Diodes for General
Purpose Applications
Rectifier Diodes
Diodes of the DS-series (anode on stud)
and of the DSI-series (cathode on stud)
are mainly used for rectifying 50 or 60 Hz
mains currents. Discrete diodes in plas-
tic and metal housings and also different
diode bridges are available for standard
line voltages (from 100 to 600 V).
Avalanche Diodes
Avalanche diodes or surge-voltage-proof
rectifier diodes of the series DSA (ano-
de on stud) and DSAI (cathode on stud)
differ from standard diodes of the series
DS and DSI in the following manner: the
operation in avalanche breakdown abo-
ve the normal reverse blocking voltage
(V
power is within the specified maximum
permissible non-repetitive reverse surge
dissipation P
Fig. 1: Current and voltage during turn-on and turn-off switching of fast diodes
a)
Fig. 3: Cross sections of glassivated planar diode chips with separation diffusion
RRM
V
I
Metalisation
) can be tolerated as long as the
a) type DWN with Anode on bottom
b) type DWP with Cathode on bottom
-di /dt
10%
t
fr
n
F
Data according to IEC 60747 and refer to a single diode or thyristor unless otherwise stated.
RSM
100% 110%
at the specified pulse
I
F
Glasspassivation
V
FR
p
V
F
-di /dt
I
width. In order to have technologically
good control of the avalanche break-
down, it is important to ensure homo-
geneous doping of the middle zone of
the silicon chip and suitable junction ter-
mination and passivation at the edges
where PN-junctions are exposed to the
surface (high field strength at the edge).
Because of this ruggedness against pe-
riodically occurring short-term voltage
surges in the blocking direction, the
user frequently can do without protec-
tive overvoltage net-works. In addition,
if avalanche diodes are put in series
for high voltage applications, the sharp
avalanche breakdown of the blocking
characteristic ensures static and dyna-
mic voltage distribution uniformly across
each device. Thus, in general, none of
the series diodes will be overstressed by
reverse voltages which are substantial-
ly above the avalanche voltage. All high
voltage rectifier modules manufactured
in quantity are assembled with avalan-
che diodes.
b)
RM
Metallisierung
F
Emitter
t
a
Q
Metalisation
t
rr
r
p
n
p
t
b
0.9 I
di /dt
R
RM
Guardring
Glaspassivierung
0.25 I
V
R
Glasspassivation
Channel stopper
RM
t
t