LM7905, LM7912, LM7915
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SNOSBQ7C – JUNE 1999 – REVISED MAY 2013
LM79XX Series 3-Terminal Negative Regulators
Check for Samples:
LM7905, LM7912, LM7915
1
FEATURES
•
Thermal, Short Circuit and Safe Area
Protection
High Ripple Rejection
1.5A Output Current
4% Tolerance on Preset Output Voltage
space
Connection Diagram
2
•
•
•
DESCRIPTION
The LM79XX series of 3-terminal regulators is
available with fixed output voltages of
−5V, −12V,
and
−15V.
These devices need only one external
component—a 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 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
datasheet.
Figure 1. TO-220 Package
Front View
See Package Number NDE0003B
Typical Applications
*Required if regulator is separated from
filter capacitor by more than 3″. For value
given, capacitor must be solid tantalum.
25μF aluminum electrolytic may be
substituted.
†Required for stability. For value given,
capacitor must be solid tantalum. 25μF
aluminum electrolytic may be substituted.
Values given may be increased without
limit.
For output capacitance in excess of 100μF,
a high current diode from input to output
(1N4001, etc.) will protect the regulator
from momentary input shorts.
Figure 2. Fixed Regulator
1
2
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of
Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
All trademarks are the property of their respective owners.
Copyright © 1999–2013, Texas Instruments Incorporated
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
LM7905, LM7912, LM7915
SNOSBQ7C – JUNE 1999 – REVISED MAY 2013
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These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam
during storage or handling to prevent electrostatic damage to the MOS gates.
ABSOLUTE MAXIMUM RATINGS
(1)
Input Voltage
(V
o
=
−5V)
(V
o
=
−12V
and
−15V)
Input-Output Differential
(V
o
=
−5V)
(V
o
=
−12V
and
−15V)
Power Dissipation
(2)
−25V
−35V
25V
30V
Internally Limited
0°C to +125°C
−65°C
to +150°C
230°C
Operating Junction Temperature Range
Storage Temperature Range
Lead Temperature (Soldering, 10 sec.)
(1)
(2)
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 ensure Specific Performance limits. For ensured specifications and test
conditions, see the Electrical Characteristics.
Refer to
DESIGN CONSIDERATIONS
for details.
ELECTRICAL CHARACTERISTICS
Conditions unless otherwise noted: I
OUT
= 500mA, C
IN
= 2.2μF, C
OUT
= 1μF, 0°C
≤
T
J
≤
+125°C, Power Dissipation
≤
1.5W.
Part Number
Output Voltage
Input Voltage (unless otherwise specified)
Symbol
V
O
Parameter
Output Voltage
T
J
= 25°C
5mA
≤
I
OUT
≤
1A,
P
≤
15W
ΔV
O
Line Regulation
T
J
= 25°C,
(1)
LM7905C
−5V
−10V
Min
−4.8
−4.75
(−20
≤
V
IN
≤ −7)
8
(−25
≤
V
IN
≤ −7)
2
(−12
≤
V
IN
≤ −8)
15
50
Typ
−5.0
Max
−5.2
−5.25
Conditions
Units
V
V
V
mV
V
mV
V
ΔV
O
Load Regulation
T
J
= 25°C,
(1)
5mA
≤
I
OUT
≤
1.5A
250mA
≤
I
OUT
≤
750mA
I
Q
ΔI
Q
Quiescent Current
Quiescent Current
Change
With Load, 5mA
≤
I
OUT
≤
1A
V
n
Output Noise Voltage
Ripple Rejection
Dropout Voltage
I
OMAX
Peak Output Current
Average Temperature
Coefficient of
Output Voltage
(1)
T
A
= 25°C, 10Hz
≤
f
≤
100Hz
f = 120Hz
T
J
= 25°C, I
OUT
= 1A
T
J
= 25°C
I
OUT
= 5mA,
0 C
≤
T
J
≤
100°C
54
T
J
= 25°C
With Line
15
5
1
(−25
≤
V
IN
≤ −7)
100
50
2
0.5
0.5
mV
mV
mA
mA
V
mA
μV
dB
V
V
A
mV/°C
125
66
(−18
≤
V
IN
≤ −8)
1.1
2.2
0.4
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.
2
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ELECTRICAL CHARACTERISTICS
Conditions unless otherwise noted: I
OUT
= 500mA, C
IN
= 2.2μF, C
OUT
= 1μF, 0°C
≤
T
J
≤
+125°C, Power Dissipation
≤
1.5W.
Part Number
Output Voltage
Input Voltage (unless otherwise specified)
Symbol
V
O
Parameter
Output Voltage
T
J
= 25°C
5mA
≤
I
OUT
≤
1A,
P
≤
15W
ΔV
O
Line Regulation
T
J
= 25°C,
(1)
LM7912C
−12V
−19V
Min
−11.5
−11.4
5
3
Typ
−12.0
Max
−12.5
−12.6
80
30
Min
−14.4
−14.25
Conditions
LM7915C
−15V
−23V
Typ
−15.0
Max
−15.6
−15.75
5
3
100
50
Units
V
V
V
mV
V
mV
V
mV
mV
mA
mA
V
mA
μV
dB
V
V
A
mV/°C
(−27
≤
V
IN
≤ −14.5)
(−30
≤
V
IN
≤ −14.5)
(−22
≤
V
IN
≤ −16)
(−30
≤
V
IN
≤ −17.5)
(−30
≤
V
IN
≤ −17.5)
(−26
≤
V
IN
≤−20)
15
5
1.5
200
75
3
0.5
(−30
≤V
IN
≤ −17.5)
0.5
375
54
70
1.1
2.2
−1.0
(−30
≤
V
IN
≤ −17.5)
ΔV
O
Load Regulation
T
J
= 25°C,
(1)
5mA
≤
I
OUT
≤
1.5A
250mA
≤
I
OUT
≤
750mA
I
Q
ΔI
Q
Quiescent Current
Quiescent Current
Change
With Load, 5mA
≤
I
OUT
≤
1A
V
n
Output Noise Voltage
Ripple Rejection
Dropout Voltage
I
OMAX
Peak Output Current
Average Temperature
Coefficient of
Output Voltage
(1)
T
A
= 25°C, 10Hz
≤
f
≤
100Hz
f = 120 Hz
T
J
= 25°C, I
OUT
= 1A
T
J
= 25°C
I
OUT
= 5mA,
0 C
≤
T
J
≤
100°C
54
T
J
= 25°C
With Line
15
5
1.5
200
75
3
0.5
(−30
≤
V
IN
≤ −14.5)
0.5
300
70
1.1
2.2
−0.8
(−25
≤
V
IN
≤ −15)
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.
Copyright © 1999–2013, Texas Instruments Incorporated
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DESIGN CONSIDERATIONS
The LM79XX fixed voltage regulator series has thermal overload protection from excessive power dissipation,
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 (125°C) 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:
Typ
Package
TO-220
θ
JC
°C/W
3.0
Max
θ
JC
°C/W
5.0
Typ
θ
JA
°C/W
60
Max
θ
JA
°C/W
40
(1)
Solving for T
J
:
T
J
= T
A
+ P
D
(θ
JC
+
θ
CA
)
or
= T
A
+ P
D
θ
JA
(without heat sink)
where
•
•
•
•
•
•
•
•
T
J
= Junction Temperature
T
A
= Ambient Temperature
P
D
= Power Dissipation
θ
JA
= Junction-to-Ambient Thermal Resistance
θ
JC
= Junction-to-Case Thermal Resistance
θ
CA
= Case-to-Ambient Thermal Resistance
θ
CS
= Case-to-Heat Sink Thermal Resistance
θ
SA
= Heat Sink-to-Ambient Thermal Resistance
Typical Applications
Bypass capacitors are necessary for stable operation of the LM79XX series of regulators over the input voltage
and output current ranges. Output bypass capacitors will improve the transient response by the regulator.
The bypass capacitors, (2.2μF on the input, 1.0μF on the output) should be ceramic or solid tantalum which have
good high frequency characteristics. If aluminum electrolytics are used, their values should be 10μF or larger.
The bypass capacitors should be mounted with the shortest leads, and if possible, directly across the regulator
terminals.
4
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LM7905 LM7912 LM7915
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SNOSBQ7C – JUNE 1999 – REVISED MAY 2013
Load and line regulation < 0.01% temperature stability
≤
0.2%
†Determine Zener current
††Solid tantalum
*Select resistors to set output voltage. 2 ppm/°C tracking suggested
Figure 3. High Stability 1 Amp Regulator
Figure 4. Current Source
*Lamp brightness increase until i
I
= i
Q
(≈ 1 mA) + 5V/R1.
†Necessary only if raw supply filter capacitor is more that 2″ from LM7905CT
Figure 5. Light Controller Using Silicon Photo Cell
Copyright © 1999–2013, Texas Instruments Incorporated
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