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LM79XX Series 3-Terminal Negative Regulators
Check for Samples: LM7905,LM7912,LM7915
1FEATURES Connection Diagram
2• Thermal, Short Circuit and Safe Area
Protection
• High Ripple Rejection
• 1.5A Output Current
• 4% Tolerance on Preset Output Voltage
space
DESCRIPTION Figure 1. TO-220 Package
The LM79XX series of 3-terminal regulators is Front View
available with fixed output voltages of −5V, −12V, and See Package Number NDE0003B
−15V. These devices need only one external
component—a compensation capacitor at the output.
The LM79XX series is packaged in the TO-220 power Typical Applications
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 *Required if regulator is separated from
current drain of these devices with a specified filter capacitor by more than 3″. For value
maximum change with line and load ensures good given, capacitor must be solid tantalum.
regulation in the voltage boosted mode. 25μF aluminum electrolytic may be
substituted.
For applications requiring other voltages, see LM137 †Required for stability. For value given,
datasheet. 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
1Please 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.
2All trademarks are the property of their respective owners.
PRODUCTION DATA information is current as of publication date. Copyright © 1999–2013, Texas Instruments Incorporated
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
(Vo=−5V) −25V
(Vo=−12V and −15V) −35V
Input-Output Differential
(Vo=−5V) 25V
(Vo=−12V and −15V) 30V
Power Dissipation (2) Internally Limited
Operating Junction Temperature Range 0°C to +125°C
Storage Temperature Range −65°C to +150°C
Lead Temperature (Soldering, 10 sec.) 230°C
(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 ensure Specific Performance limits. For ensured specifications and test
conditions, see the Electrical Characteristics.
(2) Refer to DESIGN CONSIDERATIONS for details.
ELECTRICAL CHARACTERISTICS
Conditions unless otherwise noted: IOUT = 500mA, CIN = 2.2μF, COUT = 1μF, 0°C ≤TJ≤+125°C, Power Dissipation ≤1.5W.
Part Number LM7905C Units
Output Voltage −5V
Input Voltage (unless otherwise specified) −10V
Symbol Parameter Conditions Min Typ Max
VOOutput Voltage TJ= 25°C −4.8 −5.0 −5.2 V
5mA ≤IOUT ≤1A, −4.75 −5.25 V
P≤15W (−20 ≤VIN ≤ −7) V
ΔVOLine Regulation TJ= 25°C, (1) 8 50 mV
(−25 ≤VIN ≤ −7) V
2 15 mV
(−12 ≤VIN ≤ −8) V
ΔVOLoad Regulation TJ= 25°C, (1)
5mA ≤IOUT ≤1.5A 15 100 mV
250mA ≤IOUT ≤750mA 5 50 mV
IQQuiescent Current TJ= 25°C 1 2 mA
ΔIQQuiescent Current With Line 0.5 mA
Change (−25 ≤VIN ≤ −7) V
With Load, 5mA ≤IOUT ≤1A 0.5 mA
VnOutput Noise Voltage TA= 25°C, 10Hz ≤f≤100Hz 125 μV
Ripple Rejection f = 120Hz 54 66 dB
(−18 ≤VIN ≤ −8) V
Dropout Voltage TJ= 25°C, IOUT = 1A 1.1 V
IOMAX Peak Output Current TJ= 25°C 2.2 A
Average Temperature IOUT = 5mA, 0.4 mV/°C
Coefficient of 0 C ≤TJ≤100°C
Output Voltage
(1) 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.
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ELECTRICAL CHARACTERISTICS
Conditions unless otherwise noted: IOUT = 500mA, CIN = 2.2μF, COUT = 1μF, 0°C ≤TJ≤+125°C, Power Dissipation ≤1.5W.
Part Number LM7912C LM7915C Units
Output Voltage −12V −15V
Input Voltage (unless otherwise specified) −19V −23V
Symbol Parameter Conditions Min Typ Max Min Typ Max
VOOutput Voltage TJ= 25°C −11.5 −12.0 −12.5 −14.4 −15.0 −15.6 V
5mA ≤IOUT ≤1A, −11.4 −12.6 −14.25 −15.75 V
P≤15W (−27 ≤VIN ≤ −14.5) (−30 ≤VIN ≤ −17.5) V
ΔVOLine Regulation TJ= 25°C, (1) 5 80 5 100 mV
(−30 ≤VIN ≤ −14.5) (−30 ≤VIN≤ −17.5) V
3 30 3 50 mV
(−22 ≤VIN ≤ −16) (−26 ≤VIN ≤−20) V
ΔVOLoad Regulation TJ= 25°C, (1)
5mA ≤IOUT ≤1.5A 15 200 15 200 mV
250mA ≤IOUT ≤750mA 5 75 5 75 mV
IQQuiescent Current TJ= 25°C 1.5 3 1.5 3 mA
ΔIQQuiescent Current With Line 0.5 0.5 mA
Change (−30 ≤VIN ≤ −14.5) (−30 ≤VIN ≤ −17.5) V
With Load, 5mA ≤IOUT ≤1A 0.5 0.5 mA
VnOutput Noise Voltage TA= 25°C, 10Hz ≤f≤100Hz 300 375 μV
Ripple Rejection f = 120 Hz 54 70 54 70 dB
(−25 ≤VIN ≤ −15) (−30 ≤VIN≤ −17.5) V
Dropout Voltage TJ= 25°C, IOUT = 1A 1.1 1.1 V
IOMAX Peak Output Current TJ= 25°C 2.2 2.2 A
Average Temperature IOUT = 5mA, −0.8 −1.0 mV/°C
Coefficient of 0 C ≤TJ≤100°C
Output Voltage
(1) 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.
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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 Max Typ Max
Package θJC θJC θJA θJA
°C/W °C/W °C/W °C/W
TO-220 3.0 5.0 60 40
(1)
Solving for TJ:
TJ= TA+ PD(θJC +θCA)
or = TA+ PDθJA (without heat sink)
where
• TJ= Junction Temperature
• TA= Ambient Temperature
• PD= Power Dissipation
•θJA = Junction-to-Ambient Thermal Resistance
•θJC = Junction-to-Case Thermal Resistance
•θCA = Case-to-Ambient Thermal Resistance
•θCS = Case-to-Heat Sink Thermal Resistance
•θSA = 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.
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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 iI= iQ(≈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
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*Lamp brightness increases until ii= 5V/R1 (Iican be set as low as 1 μA)
†Necessary only if raw supply filter capacitor is more that 2″from LM7905
Figure 6. High-Sensitivity Light Controller
*Improves transient response and ripple rejection. Do not increase beyond 50 μF.
Select R2 as follows:
LM7905CT 300Ω
LM7912CT 750Ω
LM7915CT 1k
Figure 7. Variable Output
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SNOSBQ7C –JUNE 1999–REVISED MAY 2013
(-15) (+15)
Load Regulation at ΔIL= 1A 40mV 2mV
Output Ripple, CIN = 3000µF, IL= 1A 100 µVms 100 µVms
Temperature Stability 50mV 50mV
Output Noise 10Hz ≤f≤10kHz 150 µVms 150 µVms
*Resistor tolerance of R4 and R5 determine matching of (+) and (−) outputs.
**Necessary only if raw supply filter capacitors are more than 3″from regulators.
Figure 8. ±15V, 1 Amp Tracking Regulators
Figure 9. Dual Trimmed Supply
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SNOSBQ7C –JUNE 1999–REVISED MAY 2013
REVISION HISTORY
Changes from Revision B (May 2013) to Revision C Page
• Changed layout of National Data Sheet to TI format. ........................................................................................................... 8
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PACKAGE OPTION ADDENDUM
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Addendum-Page 1
PACKAGING INFORMATION
Orderable Device Status
(1)
Package Type Package
Drawing Pins Package
Qty Eco Plan
(2)
Lead finish/
Ball material
(6)
MSL Peak Temp
(3)
Op Temp (°C) Device Marking
(4/5)
Samples
LM7905CT NRND TO-220 NDE 3 45 Non-RoHS
& Green Call TI Call TI 0 to 125 LM7905CT
LM7905CT/NOPB ACTIVE TO-220 NDE 3 45 RoHS & Green SN Level-1-NA-UNLIM 0 to 125 LM7905CT
LM7912CT NRND TO-220 NDE 3 45 Non-RoHS
& Green Call TI Call TI 0 to 125 LM7912CT
LM7912CT/NOPB ACTIVE TO-220 NDE 3 45 RoHS & Green SN Level-1-NA-UNLIM 0 to 125 LM7912CT
LM7915CT NRND TO-220 NDE 3 45 Non-RoHS
& Green Call TI Call TI 0 to 125 LM7915CT
LM7915CT/NOPB ACTIVE TO-220 NDE 3 45 RoHS & Green SN Level-1-NA-UNLIM 0 to 125 LM7915CT
(1) The marketing status values are defined as follows:
ACTIVE: Product device recommended for new designs.
LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.
NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design.
PREVIEW: Device has been announced but is not in production. Samples may or may not be available.
OBSOLETE: TI has discontinued the production of the device.
(2) RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance
do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may
reference these types of products as "Pb-Free".
RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption.
Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of <=1000ppm threshold. Antimony trioxide based
flame retardants must also meet the <=1000ppm threshold requirement.
(3) MSL, Peak Temp. - The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature.
(4) There may be additional marking, which relates to the logo, the lot trace code information, or the environmental category on the device.
(5) Multiple Device Markings will be inside parentheses. Only one Device Marking contained in parentheses and separated by a "~" will appear on a device. If a line is indented then it is a continuation
of the previous line and the two combined represent the entire Device Marking for that device.
PACKAGE OPTION ADDENDUM
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Addendum-Page 2
(6) Lead finish/Ball material - Orderable Devices may have multiple material finish options. Finish options are separated by a vertical ruled line. Lead finish/Ball material values may wrap to two
lines if the finish value exceeds the maximum column width.
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continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals.
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In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI to Customer on an annual basis.
MECHANICAL DATA
NDE0003B
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