LM109

ACTIVE

Extended Temperature 1A 5V Output Linear Regulator / LDO

Product details

Output options Fixed Output Iout (max) (A) 1 Vin (max) (V) 35 Vin (min) (V) 7.1 Vout (max) (V) 5 Vout (min) (V) 5 Fixed output options (V) 5 Noise (µVrms) 40 Iq (typ) (mA) 5.2 Thermal resistance θJA (°C/W) 35 Rating Military Load capacitance (min) (µF) 0 Regulated outputs (#) 1 Accuracy (%) 4 PSRR at 100 KHz (dB) 64 Dropout voltage (Vdo) (typ) (mV) 3000 Operating temperature range (°C) -55 to 150
Output options Fixed Output Iout (max) (A) 1 Vin (max) (V) 35 Vin (min) (V) 7.1 Vout (max) (V) 5 Vout (min) (V) 5 Fixed output options (V) 5 Noise (µVrms) 40 Iq (typ) (mA) 5.2 Thermal resistance θJA (°C/W) 35 Rating Military Load capacitance (min) (µF) 0 Regulated outputs (#) 1 Accuracy (%) 4 PSRR at 100 KHz (dB) 64 Dropout voltage (Vdo) (typ) (mV) 3000 Operating temperature range (°C) -55 to 150
TO-CAN (NDS) 2 969.2166 mm² 38.94 x 24.89 TO-CAN (NDT) 3 91.6742 mm² 10.03 x 9.14
  • Specified to be compatible, worst case, with TTL and DTL
  • Output current in excess of 1A
  • Internal thermal overload protection
  • No external components required

  • Specified to be compatible, worst case, with TTL and DTL
  • Output current in excess of 1A
  • Internal thermal overload protection
  • No external components required

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.


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.


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Technical documentation

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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-42 IC Provides On-Card Regulation for Logic Circuits (Rev. B) 06 May 2013
Application note Method For Cal Output Voltage Tolerances in Adj Regs (Rev. A) 05 May 2013
Application note Super Matched Bipolar Transistor Pair Sets New Standards for Drift and Noise (Rev. B) 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 High Stability Regulators 03 Oct 2002
Application note Understanding the Terms and Definitions of LDO Voltage Regulators 21 Oct 1999

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