As described more in detail in Chapter 2, prior to the measurement all control words are stored in the program memory of the digital control unit of T3Ster. These control data regulate both the power drivers and the measurement units.
The control words contain a POWER flag that sets the power drivers to their HIGH or ON state when switched on and sets them to their LOW or OFF state when switched off. The control words also contain the sampling rate for the measurement units stored in an exponential format. This means that the time interval between the actual and the next sampling can be individually determined (1 µs, 2 µs, 4 µs, up to 8 s) and the dissipation can be switched on/off individually for each sampling period.
There are different ways for measuring the thermal behaviour of semiconductor devices.
First, the power excitation can be applied to the same basic element where the thermal transient will be measured (e.g. when measuring diodes), or it may be applied to different electrodes (e.g. transistors or special thermal chips).
Second, one can measure heating-up or cooling-off transients.
In case of devices where the power is applied to and the temperature is sensed on separate ports (BJT, MOSFET, thermal test chips) heating-up or cooling-off transients are of the same nature, any of them can be selected.
In case of devices where the power is applied to the sensor element itself (i.e. diodes) the cooling-off setup can be much easier realized.
It is useful to make trial measurements with limited voltage and current values in order to make estimations on the expectable temperature changes before starting measurements with extreme conditions. In trial measurements you can use less sensitive ranges of the measurement units for recording the whole transient without overflow. In these trial measurements always select raw data capture as suggested in section 5.1.4.
It is absolutely necessary to make such trial measurements when using the power booster equipment. High power levels of the booster can easily destroy the device under test.
Always check device characteristics sheets for maximum device ratings. Check the measurement circuitry thoroughly before starting the measurement. T3Ster power sources are short-circuit protected. Still it is recommended to check the safe operation area in the T3Ster Hardware Reference Guide.
NOTE. Do not short UCB source for more than 10 seconds if T3Ster is operated above room temperature !
Trial measurements can be stopped after 30-40 seconds as most part of temperature changes have already taken place by this time.
In case of excessive temperature elevation press the STOP button immediately on the Main System Unit.