REG101

13

SBVS026C

FIGURE 7. Maximum Power Dissipation versus Ambient Temperature for the Various Packages.

POWER DISSIPATION

The REG101 is available in two different package configu-

rations. The ability to remove heat from the die is different

for each package type and, therefore, presents different

considerations in the printed circuit-board layout. The PCB

area around the device that is free of other components

moves the heat from the device to the ambient air. While it

is difficult-to-impossible to quantify all of the variables in a

thermal design of this type, performance data for several

configurations are shown in Figure 7.

Power dissipation depends on input voltage, load condition,

and duty cycle. Power dissipation is equal to the product of

the average output current times the voltage across the

Power dissipation can be minimized by using the lowest

possible input voltage necessary to assure the required

output voltage.

REGULATOR MOUNTING

Solder pad footprint recommendations for the various

REG101 devices are presented in the Application Bulletin

AB-132, “Solder Pad Recommendations for Surface-Mount

Devices” (SBFA015), available from the Texas Instruments

web site (www.ti.com).

1.2

1.0

0.8

0.6

0.4

0.3

0

0

25

50

75

100

125

Ambient Temperature (

°C)

CONDITIONS

SOT23-5

SO-8

PACKAGE

JA

SOT23-5

200

°C/W

SO-8

150

°C/W

θ

P= V

– V

I

D

IN

OUT

OUT(AVG)