Transient response of semiconductor switches for different types of load

Input task

Check typical waveforms of peak voltage and peak current and their dependence on the type of used load (R, R+L, D, R+D). Draw next dependence: peak voltage UCE as a function of peak collector current: UCE = f (ICE). Measurement should be provide for all possible loads. Keep maximum of working current (2 A) and don't over voltage transistors (UCEMAX = 100 V).

Circuit's diagram


Process of measurement

In the simple circuit of transistor-switch the load is connected with snubber combination of resistor, diode and capacitor. Voltage UCE and current IC are scanned using oscilloscope. The shunt resistor 0,3 W has a voltage potential of the DC source, so that the oscilloscope must be supplied using isolation transformer. Supply DC voltage can varies in range 0-5 V, never higher! Current flowing through the collector circuit doesn't exceed 2 A. Maximum of working voltage UCE should be 100 V. Shown waveforms save into floppy disk, see time-domain and Volt-Ampere characteristics. Working point of transistor (KD603, KD605) should be all the time in the Safe-Operating-Area (SOA), see the following figure:

Supplement information

The influence of load on the curves of IC and UCE

 
resistor load (inductance-less)load with inductors
schematic diagram 
waveform of voltage and current UCE(t), IC(t), time domain 
state diagram, movement of "working point" in the XY area, IC = f (UCE) 

Typical waveforms of voltage and current in the working collector circuit.

without snubber circuit 
with protected diode 

with damping RC combination
 
with protected diode and resistor