Datasheet

Datasheet 9 Revision 2.3, 2013-05-16
ISOFACE™
ISO1H816G
Functional Description
3.3.3 Power Transistor Overcurrent
Protection
The outputs are provided with a current limitation that
enters a repetitive switched mode after an initial peak
current has been exceeded. The initial peak short
circuit current limit is set to I
L(SCp)
at T
j
= 125°C. During
the repetitive mode short circuit current limit is set to
I
L(SCr)
. If this operation leads to an overtemperature
condition, a second protection level (T
j
> 135°C) will
change the output into a low duty cycle PWM (selective
thermal shutdown with restart) to prevent critical chip
temperatures.
Figure 5 Overtemperature detection
The following figures show the timing for a turn on into
short circuit and a short circuit in on-state. Heating up
of the chip may require several milliseconds,
depending on external conditions.
Figure 6 Turn on into short circuit, shut down by
overtemperature, restart by cooling
Figure 7 Short circuit in on-state, shut down
down by overtemperature, restart by
cooling
3.4 Common Diagnostic Output
The overtemperature detection information are OR-
wired in the common diagnostic output block. The
information is send via the integrated coreless
transformer to the input interface. The output stage at
pin DIAG has an open drain functionality combined with
a current source.
Figure 8 Common diagnostic output
IN
VOUT
T
J
t
t
t
t
DIAG
IN
VOUT
I
L
t
t
t
t
DIAG
Output short to GND
I
L(SCp)
I
L(SCr)
IN
VOUT
I
L
t
t
t
t
DIAG
Output short to GND
I
L(SCp)
I
L(SCr)
Normal
operation
Common
Diagnostic
Output
CT
100µA
VCC
DIAG