© 2006 Fairchild Semiconductor Corporation

www.fairchildsemi.com

LM78XX / LM78XXA Rev. 1.3.1

19

Typical Applications (Continued)

Figure 9. Fixed-Output Regulator

Figure 10. Constant Current Regulator

Notes:

29. To specify an output voltage, substitute voltage value for “XX”. A common ground is required between the input and

the output voltage. The input voltage must remain typically 2.0 V above the output voltage even during the low point

on the input ripple voltage.

30. CI is required if regulator is located an appreciable distance from power supply filter.

31. CO improves stability and transient response.

Figure 11. Circuit for Increasing Output Voltage

0.1

μF

CO

CI

0.33

μF

Output

Input

LM78XX

1

3

2

0.1

μF

CO

CI

0.33

μF

Output

Input

LM78XX

1

3

2

VXX

R1

RL

IQ

IO

IO = R

1

+ IQ

VXX

0.1

μF

CO

CI

0.33

μF

Output

Input

LM78XX

1

3

2

VXX

R1

R2

IQ

IRI ≥ 5 IQ

VO = VXX(1+R2/R1)+IQR2