NSC LM7912CT, LM7915CT Datasheet
LM79XX Series 3-Terminal Negative Regulators
General Description
The LM79XX series of 3-terminal regulators is available with
fixed output voltages of
These devices need only one external componentÐa compensation capacitor at the output. The LM79XX series is
packaged in the TO-220 power package and is capable of
supplying 1.5A of output current.
These regulators employ internal current limiting safe area
protection and thermal shutdown for protection against virtually all overload conditions.
Low ground pin current of the LM79XX series allows output
voltage to be easily boosted above the preset value with a
resistor divider. The low quiescent current drain of
b
5V,b8V,b12V, andb15V.
these devices with a specified maximum change with line
and load ensures good regulation in the voltage boosted
mode.
For applications requiring other voltages, see LM137 data
sheet.
Features
Y
Thermal, short circuit and safe area protection
Y
High ripple rejection
Y
1.5A output current
Y
4% tolerance on preset output voltage
LM79XX Series 3-Terminal Negative Regulators
November 1994
Connection Diagrams
TO-220 Package
TL/H/7340– 14
Front View
Order Number LM7905CT, LM7912CT or LM7915CT
See NS Package Number TO3B
Typical Applications
Fixed Regulator
TL/H/7340– 3
*Required if regulator is separated from filter capacitor by
more than 3
tantalum. 25 mF aluminum electrolytic may be substituted.
²
Required for stability. For value given, capacitor must be
solid tantalum. 25 mF aluminum electrolytic may be substituted. Values given may be increased without limit.
For output capacitance in excess of 100 mF, a high current
diode from input to output (1N4001, etc.) will protect the
regulator from momentary input shorts.
. For value given, capacitor must be solid
×
C
1995 National Semiconductor Corporation RRD-B30M115/Printed in U. S. A.
TL/H/7340
Absolute Maximum Ratings (Note 1)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales
Office/Distributors for availability and specifications.
Input Voltage
eb
(V
o
eb
(V
o
5V)
12V andb15V)
b
25V
b
35V
Input-Output Differential
eb
(V
5V) 25V
o
eb
(V
12V andb15V) 30V
o
Power Dissipation (Note 2) Internally Limited
Operating Junction Temperature Range 0§Ctoa125§C
b
Storage Temperature Range
65§Ctoa150§C
Lead Temperature (Soldering, 10 sec.) 230§C
Electrical Characteristics Conditions unless otherwise noted: I
0
CsT
§
s
a
125§C, Power Dissipations1.5W.
J
OUT
e
500 mA, C
IN
e
2.2 mF, C
Part Number LM7905C
Output Voltage
Input Voltage (unless otherwise specified)
b
5V
b
10V
Symbol Parameter Conditions Min Typ Max
V
O
Output Voltage T
e
J
5mA
Ps15W (b20sV
DV
DV
O
O
Line Regulation T
Load Regulation T
e
J
e
J
5mA
250 mAsI
I
Q
DI
Q
Quiescent Current T
Quiescent Current With Line 0.5 mA
Change (b25sV
e
J
With Load, 5 mA
V
n
Output Noise Voltage T
e
A
Ripple Rejection fe120 Hz 54 66 dB
J
J
OUT
e
e
I
OMAX
Dropout Voltage T
Peak Output Current T
Average Temperature I
Coefficient of 0 C
Output Voltage
25§C
s
s
I
1A,
OUT
25§C, (Note 3) 8 50 mV
25§C, (Note 3)
s
s
I
1.5A 15 100 mV
OUT
s
750 mA 5 50 mV
OUT
25§C12mA
s
s
I
1A 0.5 mA
OUT
25§C, 10 Hzsfs100 Hz 125 mV
25§C, I
e
1A 1.1 V
OUT
25§C 2.2 A
e
5 mA, 0.4 mV/§C
s
s
T
100§C
J
b
b
4.75
4.8
(
(
(
b
5.0
IN
b
25sV
IN
215mV
b
12sV
IN
IN
b
18sV
IN
b
5.2 V
b
s
s
s
s
s
5.25 V
b
7) V
b
7) V
b
8) V
b
7) V
b
8) V
OUT
e
1 mF,
Units
Typical Applications (Continued)
Variable Output
*Improves transient response and ripple rejection. Do not increase beyond 50 mF.
V
OUT
Select R2 as follows:
LM7905CT 300X
LM7912CT 750X
LM7915CT 1k
R1aR2
e
V
SET
R2
#
J
TL/H/7340– 2
2
Electrical Characteristics (Continued) Conditions unless otherwise noted: I
e
C
1 mF, 0§CsT
OUT
s
a
125§C, Power Dissipatione1.5W.
J
OUT
e
500 mA, C
e
2.2 mF,
IN
Part Number LM7912C LM7915C
Output Voltage
Input Voltage (unless otherwise specified)
b
12V
b
19V
b
15V
b
23V
Symbol Parameter Conditions Min Typ Max Min Typ Max
V
DV
DV
I
DI
V
Output Voltage T
O
Line Regulation T
O
Load Regulation T
O
Q
Quiescent Current T
Quiescent Current With Line 0.5 0.5 mA
Q
Change (b30sV
Output Noise Voltage T
n
e
25§C
J
5mA
Ps15W (b27sV
e
J
e
J
5mA
250 mAsI
e
J
With Load, 5 mA
e
A
s
s
I
1A,
OUT
25§C, (Note 3) 5 80 5 100 mV
25§C, (Note 3)
s
s
I
1.5A 15 200 15 200 mV
OUT
s
750 mA 5 75 5 75 mV
OUT
25§C 1.5 3 1.5 3 mA
s
I
OUT
25§C, 10 Hzsfs100 Hz 300 375 mV
Ripple Rejection fe120 Hz 54 70 54 70 dB
e
25§C, I
J
e
25§C 2.2 2.2 A
J
e
OUT
s
T
I
OMAX
Dropout Voltage T
Peak Output Current T
Average Temperature I
Coefficient of 0 C
Output Voltage
Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is
intended to be functional, but do not guarantee Specific Performance limits. For guaranteed specifications and test conditions, see the Electrical Characteristics.
Note 2: Refer to Typical Performance Characteristics and Design Considerations for details.
Note 3: Regulation is measured at a constant junction temperature by pulse testing with a low duty cycle. Changes in output voltage due to heating effects must be
taken into account.
5 mA,
s
J
e
1A 1.1 1.1 V
OUT
100§C
b
11.5b12.0b12.5b14.4b15.0b15.6 V
b
11.4
b
30sV
(
(b22sV
s
1A 0.5 0.5 mA
b
25sV
(
b
12.6b14.25
s
b
14.5) (b30sV
IN
s
b
14.5) (b30sV
IN
3 30 3 50 mV
s
b
16) (b26sV
IN
s
b
14.5) (b30sV
IN
s
b
15) (b30sV
IN
b
0.8
b
15.75 V
s
b
17.5) V
IN
s
b
17.5) V
IN
s
b
20) V
IN
s
b
17.5) V
IN
s
b
17.5) V
IN
b
1.0 mV/§C
Units
Typical Applications (Continued)
Dual Trimmed Supply
TL/H/7340– 4
3
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