Application Note
11
Revision 1.0
2017-11-15
1200V HighSpeed 3 IGBT in TO-247PLUS Evaluation Board
User Manual
Usage
3.1.4
Adjusting and monitoring the heat sink temperature
Switching losses are not only measured at room temperature but also at temperatures of 100°C and
above. Consequently, a measurement setup must offer the possibility to adjust and monitor the case
temperature of the devices under test.
This evaluation board contains a small heat sink that has been designed to serve as a small heating
element. The temperature of this element can be set and measured using the power resistor E200 and
the NTC B200, respectively. Both devices are assembled on the back of the heat sink, on the opposite
side of the devices under test.
In order to adjust the heat sink temperature:
1. Connect a laboratory power supply to the HEAT+/HEAT- terminals of the power resistor.
2. Connect an ohmmeter to the SENSE+/SENSE- terminals of the NTC thermistor.
3. Use the power supply to adjust the heat sink temperature. A rough guide is provided by Figure 8.a.
4. Monitor the actual temperature value using the ohmmeter and the NTC characteristic in Figure 8.b.
The heat sink behavior can be approximated with a thermal resistance of around 6 K/W to the ambient
and a thermal time constant of approximately 7 minutes. This analytic description is valid if the heat sink
is facing upwards and not exposed to a forced air cooling.
(a)
(b)
Figure 8
Characteristics for temperature adjustments: (a) heat sink temperature as a function of
power, (b) NTC value as a function of the heat sink temperature
3.2
Operation
As described in section 2.1 the evaluation board implements a half bridge circuit with independent driver
stages for the high side and the low side semiconductor device. Due to the universal nature of this
topology, the board can be operated in various modes of operation. The remainder of this section
explains the possible measurement configurations and procedures.
Attention: Prior to starting measurements ensure that the board settings are correct. Take
special care that no physical short circuits or floating gates are present. Increase the
input voltages slowly and monitor that the circuit behaves as expected.
3.2.1
Configurations
Table 3 provides a summary of the main board configurations. The first two lines illustrate how to study
the switching behavior of a certain IGBT and diode combination. By switching the IGBT according to a
double pulse signal it is possible to generate a turn-off as well as a turn-on event with a specific voltage