National Semiconductor Data Handbook
Summary
This series of 3-terminal negative voltage regulators provides highly reliable fixed outputs (5V, 8V, 12V, and 15V) for critical circuit designs. Engineered for superior stability, these units offer up to 1.5A output current, robust ripple rejection, and built-in protection against thermal shutdown and overload. Ideal for electronics engineers requiring dependable negative power rails in professional equipment and systems. Use this manual for detailed specifications, performance curves, and application guidance.
Page 1 Text Content
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LM79XX Series 3-Terminal Negative Regulators General Description
The LM79XX series of 3-terminal regulators is available with these devices with specified maximum change with line
fixed output voltages of b5V, b8V, b12V, and b15V. and load ensures good regulation in the voltage boosted
These devices need only one external componentÐa com- mode.
pensation capacitor at the output. The LM79XX series is For applications requiring other voltages, see LM137 data packaged in the TO-220 power package and is capable of sheet. supplying 1.5A of output current. These regulators employ internal current limiting safe area Features protection and thermal shutdown for protection against vir-
Thermal, short circuit and safe area protection
tually all overload conditions.
High ripple rejection
Low ground pin current of the LM79XX series allows output
1.5A output current
voltage to be easily boosted above the preset value with
4% tolerance on preset output voltage
resistor divider. The low quiescent current drain of
Connection Diagrams Typical Applications
TO-220 Package Fixed Regulator
TL/H/7340–3
*Required if regulator is separated from filter capacitor by
TL/H/7340–14
more than 3×. For value given, capacitor must be solid
tantalum. m F aluminum electrolytic may be substituted.
Order Number LM7905CT, LM7912CT or LM7915CT ²Required for stability. For value given, capacitor must be
See NS Package Number TO3B solid tantalum. m F aluminum electrolytic may be substi-
tuted. Values given may be increased without limit. For output capacitance in excess of m F, high current diode from input to output (1N4001, etc.) will protect the regulator from momentary input shorts.
C1995 National Semiconductor Corporation TL/H/7340 RRD-B30M115/Printed in U. S. A.
Page Summary Contents For National Semiconductor Data Handbook
Manual Details
| Brand | National |
|---|---|
| Pages | 11 |
| File Size | 154.82 KB |
| Published | May 30, 2026 |
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Frequently Asked Questions
What external components are required for the LM79XX series regulators?
These devices require at least one output compensation capacitor, and a resistor divider is necessary if you need to set a voltage above the preset value.
How does the device prevent damage from overcurrent or overheating?
The regulators employ internal current limiting, safe area protection, and thermal shutdown for defense against short circuits and overload conditions.
What is the maximum continuous output current these regulators can supply?
Under standard operating conditions, the LM79XX series can supply up to 1.5A of output current.
If I use an output capacitance greater than 100 mF, what extra protection do I need?
You must incorporate a high current diode (such as the 1N4001) from input to output to protect the regulator from momentary input shorts.