National Semiconductor LM109 LM309 5-Volt Regulator Data Sheet

LM 109/LM 5-Volt egulator

April

LM109/LM309 5-Volt Regulator

does improve transient response somewhat. Input bypass-

General Description

ing is needed, however, if the regulator is located very far

The LM109 series are complete 5V regulators fabricated on

from the filter capacitor of the power supply. Stability is also

single silicon chip. They are designed for local regulation

achieved by methods that provide very good rejection of load

on digital logic cards, eliminating the distribution problems

or line transients as are usually seen with TTL logic.

association with single-point regulation. The devices are

Although designed primarily as fixed-voltage regulator, the

available in two standard transistor packages. In the

output of the LM109 series can be set to voltages above 5V,

solid-kovar TO-5 header, it can deliver output currents in ex-

as shown. It is also possible to use the circuits as the control

cess of m A, if adequate heat sinking is provided. With

element in precision regulators, taking advantage of the

the TO-3 power package, the available output current is

good current-handling capability and the thermal overload

greater than 1A.

protection.

The regulators are essentially blowout proof. Current limiting is included to limit the peak output current to safe value. In

Features

addition, thermal shutdown is provided to keep the IC from

overheating. If internal dissipation becomes too great, the Specified to be compatible, worst case, with TTL and regulator will shut down to prevent excessive heating. DTL Output current in excess of 1A

Considerable effort was expended to make these devices

easy to use and to minimize the number of external compo- Internal thermal overload protection nents. It is not necessary to bypass the output, although this No external components required

Schematic Diagram

DS007138-1

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