6

LT1118/LT1118-2.5

LT1118-2.85/LT1118-5

OPERATIO

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:

When the regulator is sinking load current, power dissipa-

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

S8 Package

SOT-223

Free Air

120

°C/W

95

°C/W

1 Sq Inch Copper

55

°C/W

53

°C/W

4 Sq Inch Copper

35

°C/W

38

°C/W

LT1118-2.85

GND

IN

27 LINES

2.2

µF

5V

1

µF

110

Ω

110

Ω

1118 TA03

110

Ω

110

Ω

110

Ω

TERMPWR

OUT

•

•

•

•

•

•

•

•

+

LT1118-2.5

GND

IN

1

µF

1118 TA04

5V

ANALOG

COMMON

2.5V

5V

OUT

1

µF

SCSI Active Terminator

Power Supply Splitter