LT1118 Linear Technology, LT1118 Datasheet - Page 6

• Manufacturer Part Number: LT1118
• Description: Low IQ/ Low Dropout/ 800mA/ Source and Sink Regulators Adjustable and Fixed 2.5V/ 2.85V/ 5V Output
• Manufacturer: Linear Technology

OPERATIO
LT1118/LT1118-2.5
LT1118-2.85/LT1118-5
thermally connected to the die substrate. Table 1 shows
measured thermal resistance from junction to ambient for
the LT1118 connected to various sized PC board ground
planes. The power dissipated in the LT1118 varies with
input voltage and loading. When the regulator is sourcing
current the power which must be dissipated by the pack-
age is:
TYPICAL APPLICATIONS
6
P
D
= (V
IN
– V
OUT
U
) • I
LOAD
.
V
5V
IN
U
5V
+
1 F
2.2 F
IN
IN
LT1118-2.85
SCSI Active Terminator
Power Supply Splitter
GND
LT1118-2.5
TERMPWR
GND
OUT
When the regulator is sinking load current, power dissipa-
tion is nearly independent of V
Heat sinking to the IC package must consider the worst
case power dissipation which may occur.
Table 1. Measured Thermal Resistance from Junction to
Ambient for the LT1118
Free Air
1 Sq Inch Copper
4 Sq Inch Copper
OUT
P
D
1 F
= V
•
•
•
•
•
•
•
•
OUT
1 F
110
110
110
110
110
• I
LOAD
27 LINES
5V
ANALOG
COMMON
2.5V
.
1118 TA03
1118 TA04
S8 Package
120 C/W
55 C/W
35 C/W
IN
and can be calculated as:
SOT-223
95 C/W
53 C/W
38 C/W