Application Note
7
Revision 1.0
2017-11-15
1200V HighSpeed 3 IGBT in TO-247PLUS Evaluation Board
User Manual
Hardware
Table 1 compares waveforms as well as switching losses measured with the metal foil SMD resistor and
the coaxial shunt at various temperatures and voltages. As all measurements are done with exactly the
same semiconductor devices, the differences can be attributed to the different current sensors. It is
clearly visible that the SMD solution estimates the basic waveform of the collector current relatively well.
However, the exact determination of switching slopes and losses requires a coaxial shunt.
Table 1
Comparison of the coaxial (black) and the SMD shunt (red) at various conditions. The
double pulse tests were performed with IKY75N120CH3.
25°C
100°C
800V
400V
800V
400V
T
u
rn
-On
T
u
rn
-Off
Oscilloscope probe adapters
In contrast to current measurements, the acquisition of voltage waveforms is straightforward. By
selecting the emitter potential of the low side IGBT S
2
as common ground, the gate voltage, the collector-
emitter voltage and the collector current can be measured with ordinary passive probes.
While voltage probes can be connected using grounding wires and clips, the use of PCB adapters is
considered advantageous for several reasons. First and foremost, the grounding of the probe is
improved which leads to a proper and reproducible signal quality, especially in the presence of
disturbances caused by switching transients. Additionally, connecting the probes becomes more
convenient and less error-prone.
The evaluation board was designed to accommodate one PMK high voltage probe adapter A-PCB-5,0-L
and two LeCroy low voltage probe adapters PK106-4 [4][5]. They share the emitter of the low-side switch
as common ground and measure the voltage on the collector, on the gate and on the Kelvin connection
terminal, respectively. Assembling the probe adapters can be done as depicted in Figure 4.b.