Figure 5b, TRANSIENT THERMAL IMPEDANCE MODEL

Note:

Duty Factor D =

t1/t

2

Peak TJ = PDM x ZθJC + TC

t1

t2

SINGLE PULSE

1.0

RECTANGULARPULSEDURATION(SECONDS)

FIGURE 5a, MAXIMUM EFFECTIVE TRANSIENT THERMAL IMPEDANCE, JUNCTION-TO-CASE vs PULSE DURATION

0.35

0.30

0.25

0.20

0.15

0.10

0.05

0

0.5

0.1

0.3

0.7

0.05

D = 0.9

ARF475FL

Table 1 - Typical Series Equivalent Large Signal Input - Output Impedance

Freq. (MHz)

Zin (Ω) gate to gate

Z

30

60

90

120

150

5.2 -j10

1.37 -j5.2

.53 -j2.6

.25 -j1.0

.25 +j0.2

41 -j20

26 -j25

16 -j23

10 -j20

6.7 -j17

Z

Conjugate of optimum load for 600 Watts peak output at Vdd = 150V

25% duty cycle and PW = 5ms

0.142

0.169

0.00719

0.0856

Power

(watts)

RC MODEL

Junction

temp. (

°C)

Case temperature. (

°C)