MJE5850, MJE5851, MJE5852

www.onsemi.com

5

SWITCHING TIMES NOTE

In resistive switching circuits, rise, fall, and storage times

have been defined and apply to both current and voltage

waveforms since they are in phase. However, for inductive

loads which are common to SWITCHMODE power

supplies and hammer drivers, current and voltage

waveforms

are

not

in

phase.

Therefore,

separate

measurements must be made on each waveform to

determine the total switching time. For this reason, the

following new terms have been defined.

An enlarged portion of the inductive switching waveform

is shown in Figure 7 to aid on the visual identity of these

terms.

For the designer, there is minimal switching loss during

storage time and the predominant switching power losses

occur during the crossover interval and can be obtained

using the standard equation from AN−222A:

this relationship may not be valid.

As is common with most switching transistors, resistive

switching is specified at 25

°C and has become a benchmark

for designers. However, for designers of high frequency

converter circuits, the user oriented specifications which

make this a “SWITCHMODE” transistor are the inductive

_C.

t, TIME (ms)

1

0.01

0.01

0.7

0.2

0.1

0.05

0.02

0.05

1

2

5

10

20

50

100

200

500

D CURVES APPLY FOR POWER

PULSE TRAIN SHOWN

D = 0.5

0.2

0.01

SINGLE PULSE

0.1

0.1

0.5

0.2

1 k

0.5

0.3

0.07

0.03

0.02

Figure 9. Turn−On Switching Times

Figure 10. Turn−Off Switching Time

0.1

0.3

0.2

10

0.4

0.02

0.01

1.0

0.7

0.3

0.2

0.5

0.1

0.7

3.0

10

2.0

5.0

0.1

1.0

7.0

0.5

0.03

0.05

0.07

0.7

0.3

0.2

0.7

4.0

10

0.1

2.0

7.0

0.5

0.3

1.0

0.02

0.05