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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.


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

If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. Input Voltage Power Dissipation 35V Internally Limited

Operating Junction Temperature Range LM109 LM309 Storage Temperature Range Lead Temperature (Soldering, 10 sec.)

Parameter Output Voltage Line Regulation Load Regulation TO-39 Package TO-3 Package Output Voltage Conditions Min 25°C 7.10V VIN 5 mA IOUT 5 mA IOUT 1.5A 7.40V VIN 5 mA IOUT IMAX, P < PMAX Quiescent Current Quiescent Current Change Output Noise Voltage Long Term Stability Ripple Rejection Thermal Resistance, Junction to Case TO-39 Package TO-3 Package °C/W = 25°C (Note 50 7.40V VIN 25V 7.40V VIN 5 mA IOUT IMAX f 100 kHz 4.7 LM109 Typ 5.05 4.0 Max 5.3 50 Min 4.8 LM309 Typ 5.05 4.0 Max V mV Units

Note 1: "Absolute Maximum Ratings" indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is functional, but do not guarantee specific performance limits. Note 2: Unless otherwise specified, these specifications apply Tj +150°C for the LM109 and Tj +125°C for the LM309; VIN = 10V; and IOUT = 0.1A for the TO-39 package or IOUT = 0.5A for the TO-3 package. For the TO-39 package, IMAX = 0.2A and PMAX = 2.0W. For the TO-3 package, IMAX = 1.0A and PMAX = 20W. Note 3: Without a heat sink, the thermal resistance of the TO-39 package is about 150°C/W, while that of the TO-3 package is approximately 35°C/W. With a heat sink, the effective thermal resistance can only approach the values specified, depending on the efficiency of the sink. Note 4: Refer to RETS109H drawing for or RETS109K drawing for LM109K military specifications.

Order Number LM109K STEEL or LM309K STEEL See NS Package Number K02A Order Number LM109K/883 See NS Package Number K02C

1. Bypass the input of the LM109 to ground with 0.2 µF ceramic or solid tantalum capacitor if main filter capacitor is more than 4 inches away. 2. Avoid insertion of regulator into "live" socket if input voltage is greater than 10V. The output will rise to within 2V of the unregulated input if the ground pin does not make contact, possibly damaging the load. The LM109 may also be damaged if a large output capacitor is charged up, then discharged through the internal clamp zener when the ground pin makes contact. 3. The output clamp zener is designed to absorb transients only. It will not clamp the output effectively if a failure occurs in the internal power transistor structure. Zener dynamic impedance is 4. Continuous RMS current into the zener should not exceed 0.5A. 4. Paralleling of LM109s for higher output current is not recommended. Current sharing will be almost nonexistent, leading to a current limit mode operation for devices with the highest initial output voltage. The current limit devices may also heat up to the thermal shutdown point ( 175°C). Long term reliability cannot be guaranteed under these conditions.

Preventing latchoff for loads connected to negative voltage: If the output of the LM109 is pulled negative by a high current supply so that the output pin is more than 0.5V negative with respect to the ground pin, the LM109 can latch off. This can be prevented by clamping the ground pin to the output pin with a germanium or Schottky diode as shown. A silicon diode (1N4001) at the output is also needed to keep the positive output from being pulled too far negative. The 10 resistor will raise +VOUT by 0.05V.

*Zener is internal LM109. **Q1 must be able to withstand 7A continuous current if fusing is not used at regulator input. LM109 bond wires will fuse at currents above Q2 is selected for surge capability. Consideration must be given to filter capacitor size, transformer impedance, and fuse blowing time. Trip point is 7.5V.

Maximum Average Power Dissipation (LM109K) Maximum Average Power Dissipation (LM309K) Output Impedance

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