Fairchild LM78 Series User manual

LM78XX / LM78XXA — 3-Terminal 1 A Positive Voltage Regulator
© 2006 Fairchild Semiconductor Corporation www.fairchildsemi.com
LM78XX / LM78XXA Rev. 1.3.1
September 2014
LM78XX / LM78XXA
3-Terminal 1 A Positive Voltage Regulator
Features
• Output Current up to 1 A
• Output Voltages: 5, 6, 8, 9, 10, 12, 15, 18, 24 V
• Thermal Overload Protection
• Short-Circuit Protection
• Output Transistor Safe Operating Area Protection
Ordering Information(1)
Note:
1. Above output voltage tolerance is available at 25°C.
Product Number Output Voltage
Tolerance Package Operating
Temperature Packing Method
LM7805CT
±4%
TO-220
(Single Gauge)
-40°C to +125°C
Rail
LM7806CT
LM7808CT
LM7809CT
LM7810CT
LM7812CT
LM7815CT
LM7818CT
LM7824CT
LM7805ACT
±2% 0°C to +125°C
LM7809ACT
LM7810ACT
LM7812ACT
LM7815ACT
Description
The LM78XX series of three-terminal positive regulators
is available in the TO-220 package and with several fixed
output voltages, making them useful in a wide range of
applications. Each type employs internal current limiting,
thermal shut-down, and safe operating area protection. If
adequate heat sinking is provided, they can deliver over
1 A output current. Although designed primarily as fixed-
voltage regulators, these devices can be used with exter-
nal components for adjustable voltages and currents.
1
1. Input
2. GND
3. Output
GND
TO-220 (Single Gauge)

LM78XX / LM78XXA — 3-Terminal 1 A Positive Voltage Regulator
© 2006 Fairchild Semiconductor Corporation www.fairchildsemi.com
LM78XX / LM78XXA Rev. 1.3.1 18
Typical Applications
Figure 6. DC Parameters
Figure 7. Load Regulation
Figure 8. Ripple Rejection
0.1μF
CO
CI0.33μF
Output
Input
LM78XX
13
2
LM78XX
3
2
1
0.33μF
270pF
100Ω30μS
RL
2N6121
or EQ
Output
Input
VO
0V
VO
LM78XX
Output
Input
5.1Ω
0.33μF 2
31
RL
470μF
120Hz +

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. CIis required if regulator is located an appreciable distance from power supply filter.
31. COimproves stability and transient response.
Figure 11. Circuit for Increasing Output Voltage
0.1μF
CO
CI0.33μF
Output
Input
LM78XX
13
2
0.1μF
CO
CI0.33μF
Output
Input
LM78XX
13
2VXX
R1
RL
IQ
IO
IO = R1+IQ
VXX
0.1μF
CO
CI0.33μF
Output
Input
LM78XX
13
2VXX R1
R2
IQ
IRI ≥5 IQ
VO= VXX(1+R2/R1)+IQR2

LM78XX / LM78XXA — 3-Terminal 1 A Positive Voltage Regulator
© 2006 Fairchild Semiconductor Corporation www.fairchildsemi.com
LM78XX / LM78XXA Rev. 1.3.1 20
Typical Applications (Continued)
Figure 12. Adjustable Output Regulator (7 V to 30 V)
Figure 13. High-Current Voltage Regulator
Figure 14. High Output Current with Short-Circuit Protection
LM741
-
+
2
3
6
4
2
3
1
0.33μF
CI
Input Output
0.1μF
CO
LM7805
10kΩ
IRI ≥5 IQ
VO= VXX(1+R2/R1)+IQR2
3
2
1
LM78XX
Output
Input
R1
3Ω
0.33μF
IREG
0.1μF
IO
IQ1
IO= IREG + BQ1 (IREG–VBEQ1/R1)
Q1 BD536
R1 = VBEQ1
IREG–IQ1 BQ1
/
LM78XX
Output
0.1μF
0.33μF
R1
3Ω
3
2
1
Q1
Input
Q2
Q1 = TIP42
Q2 = TIP42
RSC = I
SC
VBEQ2
RSC

LM78XX / LM78XXA — 3-Terminal 1 A Positive Voltage Regulator
© 2006 Fairchild Semiconductor Corporation www.fairchildsemi.com
LM78XX / LM78XXA Rev. 1.3.1 21
Typical Applications (Continued)
Figure 15. Tracking Voltage Regulator
Figure 16. Split Power Supply (±15 V - 1 A)
LM78XX
LM741
0.1μF
0.33μF
1
2
3
72
6
434.7kΩ
4.7kΩ
TIP42
COMMON
COMMON
VO
-VO
VI
-VIN
_
+
3
1
2
1
3
2
0.33μF 0.1μF
2.2μF
1μF +
+
1N4001
1N4001
+15V
-15V
+20V
-20V
LM7815
MC7915

LM78XX / LM78XXA — 3-Terminal 1 A Positive Voltage Regulator
© 2006 Fairchild Semiconductor Corporation www.fairchildsemi.com
LM78XX / LM78XXA Rev. 1.3.1 22
Typical Applications (Continued)
Figure 17. Negative Output Voltage Circuit
Figure 18. Switching Regulator
LM78XX
Output
Input
+
1
2
0.1μF
3
LM78XX
1mH
3
1
2
2000μF
Output
Input D45H11
0.33μF
470Ω
4.7Ω
10μF
0.5Ω
Z1
+
+