MBRB30H30CT−1

http://onsemi.com

5

MERCURY

SWITCH

DUT

10 mH COIL

t

Figure 9. Test Circuit

Figure 10. Current−Voltage Waveforms

The unclamped inductive switching circuit shown in

Figure 9 was used to demonstrate the controlled avalanche

capability of this device. A mercury switch was used instead

of an electronic switch to simulate a noisy environment

when the switch was being opened.

is opened and the voltage across the diode under test begins

to rise rapidly, due to di/dt effects, when this induced voltage

reaches the breakdown voltage of the diode, it is clamped at

which now starts to decay linearly through the diode, and

is opened; and calculating the energy that is transferred to

the diode it can be shown that the total energy transferred is

equal to the energy stored in the inductor plus a finite amount

component resistances. Assuming the component resistive

elements are small Equation (1) approximates the total

energy transferred to the diode. It can be seen from this

breakdown voltage of the device, the amount of energy

contributed by the supply during breakdown is small and the

total energy can be assumed to be nearly equal to the energy

Equation (2).

W

AVAL [

1

2

LI

2

LPK

BV

DUT

BV

DUT

–V

DD

W

AVAL [

1

2

LI

2

LPK

EQUATION (1):

EQUATION (2):