© by SEMIKRON
/ 2017-09-07 /
Technical Explanation
/ SKiiP
®
4
Page 21/73
5.2.4
Switching Signal Inputs
The switching signal inputs HB_TOP for the TOP IGBT and HB_BOT for the BOT IGBT have a digital positive
/ active high logic (input HIGH = IGBT on; input LOW = IGBT off) characteristic.
For driving the inputs HB_TOP and HB_BOT it is mandatory to use line drivers with a push-pull
characteristic. Pull up and open collector output stages must not be used for driving these inputs. It is
recommended to chose line drivers (e.g. IXDD604) according to the length of the signal wires.
Please note:
A non-connected input will be considered as LOW signal.
Figure 5.5: TOP/BOT PWM Signal Input
A 1nF capacitor is connected to the
switching signal input to obtain high
noise immunity. This capacitor can
cause a delay of few ns for current
limited line drivers, which can be
neglected.
Input resistance is about 13kOhm
As shown in Figure 5.7. the switching signal will be considered as:
•
High when > V
IT+
•
Low when < V
IT-
Figure 5.6: Threshold level for HB_TOP and HB_BOT
The threshold values V
IT+
and V
IT
- are given in the corresponding SKiiP
®
4 datasheet on page 2.
V
IT+
: Minimum threshold that guarantees that input voltage level is recognized to switch on the IGBT.
V
IT-
: Maximum threshold that guarantees that input voltage level is recognized to switch off the IGBT.
All threshold values are related to the supply voltage V
s
.
