Concept2 2SC0435T, Руководство по описанию и применению

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2SC0435T
Target
IGBT-Driver.com Page 13
V
CE
monitoring / short-circuit protection
Each channel of the 2SC0435T driver is equipped
with a V
CE
monitoring circuit. The recommended
external circuitry is shown in Fig. 6. A resistor
(R
thx
in Fig. 6) is used as the reference element
for defining the turn-off threshold. The value of
the current through R
thx
is 150 μ A (typical). It is
recommended to choose threshold levels of about
10V (R
thx
values around 68k Ω ). In this case the
driver will safely protect the IGBT against short-
circuit, but not necessarily against overcurrent.
Overcurrent protection has a lower timing priority
and is recommended to be realized within the
host controller.
In order to ensure that the 2SC0435T can be
applied as universally as possible, the response
time capacitor C
ax
is not integrated in the driver,
but must be connected externally.
During the response time, the V
CE
monitoring
circuit is inactive. The response time is the time
that elapses after turn-on of the power
semiconductor until the collector/drain voltage is
measured (see Fig. 7).
Both IGBT collector-emitter voltages are
measured individually. V
CE
is checked after the
response time at turn-on to detect a short circuit
or overcurrent. If the measured V
CE
at the end of
the response time is higher than the programmed
threshold V
thx
, the driver detects a short circuit or overcurrent. The driver then switches off the corresponding
power semiconductor. The fault status is immediately transferred to the corresponding SOx output of the
affected channel. The power semiconductor is kept in off state (non-conducting) and the fault is shown at pin
SOx as long as the blocking time T
B
is active.
The blocking time T
B
is applied independently to each channel. T
B
starts as soon as V
CE
exceeds the threshold
of the V
CE
monitoring circuit outside the response time span.
The value of the response time capacitors C
ax
can be determined with the following table in order to set the
desired response time (R
vcex
=1.8M Ω , DC-link voltage V
DC-LINK
>550V):
Input
Voltage
Driver
Gate
Voltage
0V
+15V
+3.3...15V
0V
+Vdc
Vthx
Collector/Drain
Voltage
0V
Response time
Fig. 7 Turn-on characteristic of an IGBT or
MOSFET