2002. 9. 24

9/9

KIA79M05F~KIA79M15F

Revision No : 2

Design Considerations

The KIA79MXX fixed voltage regulator series have thermal

overload protection from excessive power, internal short circuit

protection which limits the circuit's maximum current, and output

transistor safe-area compensation for reducing the output current

as the voltage across the pass transistor is increased.

Although the internal power dissipation is limited, the junction

temperature must be kept below the maximum specified temperature

in order to meet data sheet specifications. To calculate the maximum

junction temperature or heat sink required, the following thermal

resistance values should be used ;

or

=

(Without a Heat Sink)

JA

Where

Typical Applications

Bypass capacitors are necessary for stable operation of the

KIA79MXX series of regulators over the input voltage and output

current ranges. Output bypass capacitors will improve the transient

response of the regulator.

The bypass capacitors (2.2 F on the input, 1.0 F on the output),

Should be ceramic or solid tantalum which have good high frequency

characteristics. If aluminum electrolytics are used, their values

should be 10 F or larger. The bypass capacitors should be mounted

with the shortest leads, and if possible, directly across the regulator

terminals.

(1) Required if regulator is separated from filter capacitor by

more than 3. For value given, capacitor must be solid tantalum.

25 F aluminum electrolytic may be substituted.

(2) Required for stability. For value given, capacitor must be solid

tantalum. 25 F aluminum electrolytic may be substituted.

Values given may be increased without limit.

For output capacitance in excess of 100 F, a high current

diode from input to output (1N4001, etc.) will protect the

regulator from momentary input shorts.

* Improves transient response and ripple rejection.

Do not increase beyond 50 F.

R1+R2

)

R2

Select R2 as follows :

KIA79M05

300

KIA79M08

470

KIA79M12

750

KIA79M15

1k

PACKAGE

/W)

/W)

DPAK

10.4

96.1

KIA79MXX

+

-

+

-

C

2.2

µF

1

2

C

1

µF

Fixed Regulator

Input

Output

(1)

(2)

2.2

µF

-

+

1

C

-

+

KIA79MXX

-

+

SOLID

TANTALUM

C

25

µF

3

1

R

TANTALUM

C

1

µF

SOLID

2

25

µF

Varlable Output

*

INPUT

OUTPUT