0

0.05

0.10

0.15

0.20

0.25

0.30

10

1.0

-1

VRF2933

Peak TJ = PDM x ZθJC + TC

Duty Factor D =

2

t2

t1

Note:

RECTANGULAR PULSE DURATION (seconds)

Figure 5. Maximum Effective Transient Thermal Impedance Junction-to-Case vs Pulse Duration

0

50

100

150

200

250

300

350

400

450

500

0

0.5

1

1.5

2

2.5

3

0

50

100

150

200

250

300

350

400

450

500

0

2

4

6

8

10

12

P

Figure 6. P

P

Figure 7. P

50V

40V

Freq=30MHz

Freq=65MHz

FIGURE 5b, TRANSIENT THERMAL IMPEDANCE MODEL

Dissipated Power

(Watts)

T

T

Z

impedances: Case to sink,

sink to ambient, etc. Set to

zero when modeling only

the case to junction.

.079

.076

.115

.009

.080

.224

Table 1 - Typical Class AB Large Signal Input - Output Impedance

Z

I

Z

Freq. (MHz)

Z

in

Z

out

2

23.6 - j 5.5

4.0 - j 0.1

13.5

7.6 - j 10.1

3.9 - j 0.6

27.1

3.5 - j 6.0

3.7 - j 1.1

40.7

2.5 - j 4.0

3.3 - j 1.5

65

1.95 - j 2.07

2.6 - j 1.9

100

1.8 - j 0.66

1.76 - j 0.2

150

1.78 + j 0.5

1.03 + j 1.7

0.3

D = 0.9

0.7

SINGLE PULSE

0.5

0.1

0.05

50V

40V