5V/3.3V or Adjustable, Low-Dropout,

10

______________________________________________________________________________________

The GND pins of the MAX882/MAX883/MAX884 SOIC

package perform the dual function of providing an elect-

rical connection to ground and channeling heat away. Con-

nect all GND pins to ground using a large pad or ground

plane. Where this is impossible, place a copper plane on an

adjacent layer. For a given power dissipation, the pad

should exceed the associated dimensions in Figure 4.

Figure 4 assumes the IC is in an 8-pin small-outline pack-

age that has a maximum junction temperature of +125°C

and is soldered directly to the pad; it also has a +25°C

ambient air temperature and no other heat sources. Use

larger pad sizes for other packages, lower junction tem-

peratures, higher ambient temperatures, or conditions

where the IC is not soldered directly to the heat-sinking

ground pad. When operating C- and E-grade parts up to a

output voltage may drift more.

The MAX882/MAX883/MAX884 can regulate currents up

to 250mA and operate with input voltages up to 11.5V, but

not simultaneously. High output currents can only be sus-

tained when input-output differential voltages are small, as

shown in Figure 5. Maximum power dissipation depends

on packaging, temperature, and air flow. The maximum

output current is as follows:

where P is derived from Figure 4.

I

P(T

T )

(V

V

)100 C

OUT(MAX)

JA

IN

OUT

=

−

−°

1.0

0.9

1.6

1.5

1.4

1.3

1.2

1.1

COPPER GROUND PAD AREA

8-PIN SO PACKAGE

SINGLE-SIDED BOARD

1oz COPPER

GLASS EPOXY,

250

200

150

100

50

0

SUPPLY VOLTAGE (V)

5

4

3

27

68

10

911

13

12

MAXIMUM POWER

DISSIPATION LIMIT

HIGH-

POWER

SOIC

PLASTIC DIP

CERAMIC DIP

MAXIMUM CURRENT

OPERATING

REGION AT

250

200

150

100

50

0

SUPPLY VOLTAGE (V)

5

47

68

10

911

13

12

MAXIMUM POWER

DISSIPATION LIMIT

HIGH-

POWER

SOIC

PLASTIC DIP

CERAMIC DIP

MAXIMUM CURRENT

OPERATING

REGION AT

Figure 4. Typical Maximum Power Dissipation vs. Ground Pad

Area

Figure 5a. Safe Operating Regions: MAX882/MAX884 Maximum

Output Current vs. Supply Voltage

Figure 5b. Safe Operating Regions: MAX883 Maximum Output

Current vs. Supply Voltage