Data Sheet

LM78XX / LM78XXA — 3-Terminal 1 A Positive Voltage Regulator
© 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. C
I
is required if regulator is located an appreciable distance from power supply filter.
31. C
O
improves stability and transient response.
Figure 11. Circuit for Increasing Output Voltage
0.1μF
C
O
C
I
0.33μF
Output
Input
LM78XX
1
3
2
0.1μF
C
O
C
I
0.33μF
Output
Input
LM78XX
1
3
2
V
XX
R
1
R
L
I
Q
I
O
I
O
=
R
1
+
I
Q
V
XX
0.1μF
C
O
C
I
0.33μF
Output
Input
LM78XX
1
3
2
V
XX
R1
R2
I
Q
I
RI
≥ 5 I
Q
V
O
= V
XX
(1 + R
2
/ R
1
) + I
Q
R
2