AAT1204 AAT, AAT1204 Datasheet - Page 10

• Manufacturer Part Number: AAT1204
• Description: MULTI-INPUT LOW-DROPOUT REGULATOR
• Manufacturer: AAT

To ensure reliable operation of the device, the junction temperature of the output device must be within the
safe operating area（SOA）. This is achieved by having a means to dissipate the heat generated from the
junction of the output structure. There are two components that contribute to thermal resistance. They
consist of two paths in series. The first is the junction to case thermal resistance, R
to ambient thermal resistance, R
by：
The ability to efficiently dissipate the heat from the junction is a function of the package style and board
layout incorporated in the application. The operating junction temperature is determined by the operation
ambient temperature, T
The junction temperature, T
This particular application uses the 8-pin SO package with standard lead frame with a dedicated ground
terminal. Hence, the maximum power dissipation allowable for an operating ambient temperature of 70℃,
and a maximum junction temperature of 150℃ is determined as：
Worst case maximum power dissipation is determined by：
Normal operating maximum power dissipation is：
Note: The thermal characteristics of the AAT1204 were measured using a double-sided board with two
square inches of copper area connected to the GND pins for "heat spreading". The use of multi-layer
board construction with power planes will further enhance the thermal performance of the package.
T
T
P
P
P
P
R
J
J
D
D
J
J
＝（T
＝（150－70）/70＝1.1W
＝T
＝T
JA
＝（5.5－3.135）×0.4＝0.946W
＝（5－3.3）×0.4＝0.68W
＝R
A
A
＋P
＋P
JC
J
－T
Advanced Analog Technology, Inc.
＋R
J
J
（R
（R
A
A
CA
）/ R
, and the junction power dissipation, P
JC
JA
）＋P
J
）
–
, is equal to the following thermal equation：
JA
Advanced Analog Technology, Inc
台灣類比科技股份有限公司
CA
J
（R
. The overall junction to ambient thermal resistance, R
THERMAL INFORMATION
CA
）
J
.
–
.
JC
; the second is the case
AAT1204
JA
, is determined
V 1.0