AN1908 Freescale Semiconductor / Motorola, AN1908 Datasheet - Page 5

• Manufacturer Part Number: AN1908
• Description: Solder Mounting Method for the MRF19090S and Similar Packages
• Manufacturer: Freescale Semiconductor / Motorola

RESULTS
and 135 Watts of dissipated power. At 90 Watts of RF output
power at 40% efficiency, the dissipated power is 135 Watts (see
Figure 10). A peak case temperature of more than 90 C was
achieved as measured by a thermocouple directly under the
MOTOROLA SEMICONDUCTOR APPLICATION INFORMATION
The assemblies were cycled under DC conditions at 26 Volts
135
115
95
75
55
35
15
–5
0
Freescale Semiconductor, Inc.
Figure 10. Power as a Function of Time for One Cycle
For More Information On This Product,
5
Dissipated Power vs Time
10
Figure 9. Power Life Test Board
Go to: www.freescale.com
TIME (MINUTES)
(One Cycle)
15
Die Junction 175 C
20
heatsink of each device. The MRF19090S device has the
specified junction to case resistance (
this, the junction temperature at 135 Watts power dissipation will
be 180 C when the sink temperature is 90 C. The temperature
rise is calculated based on the
The devices were powered at a 50% duty cycle for 2000 cycles,
representing 1000 hours of cycling.
25
30
Die Junction at
Room Temperature
Power
JC
plus the interface resistance.
JC )
of 0.65 C/W. Based on
AN1908
5