The LM109 series are complete 5V regulators fabricated on a single silicon chip. They are designed for local regulation on digital logic cards, eliminating the distribution problems association with single-point regulation. The devices are available in two standard transistor packages. In the solid-kovar TO-5 header, it can deliver output currents in excess of 200 mA, if adequate heat sinking is provided. With the TO-3 power package, the available output current is greater than 1A.
The regulators are essentially blowout proof. Current limiting is included to limit the peak output current to a safe value. In addition, thermal shutdown is provided to keep the IC from overheating. If internal dissipation becomes too great, the regulator will shut down to prevent excessive heating.
Considerable effort was expended to make these devices easy to use and to minimize the number of external components. It is not necessary to bypass the output, although this does improve transient response somewhat. Input bypassing is needed, however, if the regulator is located very far from the filter capacitor of the power supply. Stability is also achieved by methods that provide very good rejection of load or line transients as are usually seen with TTL logic.
Although designed primarily as a fixed-voltage regulator, the output of the LM109 series can be set to voltages above 5V, as shown. It is also possible to use the circuits as the control element in precision regulators, taking advantage of the good current-handling capability and the thermal overload protection.
| Type | Title | Date | ||
|---|---|---|---|---|
| * | Data sheet | LM109/LM309 5-Volt Regulator datasheet (Rev. A) | 03 May 2004 | |
| Application note | A Topical Index of TI LDO Application Notes (Rev. F) | 27 Jun 2019 | ||
| Application note | AN-103 LM340 Series Three Terminal Positive Regulators (Rev. A) | 06 May 2013 | ||
| Application note | AN-1148 Linear Regulators: Theory of Operation and Compensation (Rev. B) | 06 May 2013 | ||
| Application note | AN-182 Improving Power Supply Reliability with IC Power Regulators (Rev. B) | 05 May 2013 | ||
| Application note | Method For Cal Output Voltage Tolerances in Adj Regs (Rev. A) | 05 May 2013 | ||
| Application note | Packaging Limits Range of Linear Regulators | 08 May 2010 | ||
| Application note | Digital Designer's Guide to Linear Voltage Regulators & Thermal Mgmt (LDO) (Rev. A) | 04 Jun 2008 | ||
| Application note | Linear and Switching Voltage Regulator Fundamental Part 1 | 21 Mar 2007 | ||
| Application note | Understanding the Terms and Definitions of LDO Voltage Regulators | 21 Oct 1999 |
For additional terms or required resources, click any title below to view the detail page where available.
| Package | Pins | CAD symbols, footprints & 3D models |
|---|---|---|
| TO-CAN (NDS) | 2 | Ultra Librarian |
| TO-CAN (NDT) | 3 | Ultra Librarian |
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