LM309.PDF

January 1995

LM109/LM309 5-Volt Regulator

General Description

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 compo-

nents. It is not necessary to bypass the output, although this

does improve transient response somewhat. Input bypass-

ing 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 con-

trol element in precision regulators, taking advantage of the

good current-handling capability and the thermal overload

protection.

Features

Y Specified to be compatible, worst case, with TTL and

DTL

Y Output current in excess of 1A

Y Internal thermal overload protection

Y No external components required

Schematic Diagram

TL/H/7138±1

C 1995 National Semiconductor Corporation

TL/H/7138

RRD-B30M115/Printed in U. S. A.

Absolute Maximum Ratings

If Military/Aerospace specified devices are required,

please contact the National Semiconductor Sales

Office/Distributors for availability and specifications.

(Note 3)

Input Voltage

Operating Junction Temperature Range

LM109

b 55 § Cto a 150 § C

LM309

0 § Cto a 125 § C

Storage Temperature Range

b 65 § Cto a 150 § C

35V

Lead Temperature (Soldering, 10 sec.)

300 § C

Power Dissipation

Internally Limited

Electrical Characteristics (Note 1)

Parameter

Conditions

LM109

LM309

Units

Min Typ Max Min Typ Max

Output Voltage

T j e 25 § C

4.7

5.05

5.3

4.8

5.05

5.2

Line Regulation

T j e 25 § C

4.0

50 mV

7.10V s V IN s 25V

Load Regulation

T j e 25 § C

TO-39 Package

5 mA s I OUT s 0.5A

50 mV

TO-3 Package

5 mA s I OUT s 1.5A

100

100 mV

Output Voltage

7.40V s V IN s 25V,

4.6

5.4

4.75

5.25

5mA s I OUT s I MAX ,

P k P MAX

Quiescent Current

7.40V s V IN s 25V

5.2

10 mA

Quiescent Current Change 7.40V s V IN s 25V

0.5

0.5 mA

5mA s I OUT s I MAX

0.8

0.8 mA

Output Noise Voltage

T A e 25 § C

m V

10 Hz s f s 100 kHz

Long Term Stability

Ripple Rejection

T j e 25 § C

Thermal Resistance,

(Note 2)

Junction to Case

TO-39 Package 15 15 § C/W

TO-3 Package 2.5 2.5 § C/W

Note 1: Unless otherwise specified, these specifications apply b 55 § C s T j s a 150 § C for the LM109 and 0 § C s T j s a 125 § C for the LM309; V IN e 10V; and

I OUT e 0.1A for the TO-39 package or I OUT e 0.5A for the TO-3 package. For the TO-39 package, I MAX e 0.2A and P MAX e 2.0W. For the TO-3 package, I MAX

e 1.0A and P MAX e 20W.

Note 2: 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 3: Refer to RETS109H drawing for LM109H or RETS109K drawing for LM109K military specifications.

Connection Diagrams

Metal Can Packages

TL/H/7138±3

Order Number LM109H, LM109H/883 or LM309H

See NS Package Number H03A

Order Number LM109K STEEL or LM309K STEEL

See NS Package Number K02A

Order Number LM109K/883

See NS Package Number K02C

Application Hints

a. Bypass the input of the LM109 to ground with t 0.2 m F

ceramic or solid tantalum capacitor if main filter capacitor

is more than 4 inches away.

b. 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.

c. The output clamp zener is designed to absorb tran-

sients only. It will not clamp the output effectively if a

failure occurs in the internal power transistor structure.

Zener dynamic impedance is & 4 X . Continuous RMS

current into the zener should not exceed 0.5A.

d. Paralleling of LM109s for higher output current is not

recommended. Current sharing will be almost nonexis-

tent, 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.

e. Preventing latchoff for loads connected to negative

voltage:

If the output of the LM109 is pulled negative by a high cur-

rent 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 X

resistor will raise a V OUT by & 0.05V.

TL/H/7138±7

Crowbar Overvoltage Protection

Input Crowbar

Output Crowbar

TL/H/7138±8

TL/H/7138±9

*Zener is internal to 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 7A.

Q2 is selected for surge capability. Consideration must be given to filter capacitor size, transformer impedance, and fuse blowing time.

²² Trip point is & 7.5V.

Typical Performance Characteristics

Maximum Average

Power Dissipation (LM109K)

Power Dissipation (LM309K)

Output Impedance

TL/H/7138±10

Maximum Average

Power Dissipation (LM109H)

Power Dissipation (LM309H)

Ripple Rejection

TL/H/7138±11

Current Limit

Thermally Induced Output

Characteristics (Note 1)

Voltage Variation

Ripple Rejection

TL/H/7138±12

Note 1: Current limiting foldback characteristics

are determined by input output differen-

tial, not by output voltage.

Typical Performance Characteristics (Continued)

Input-Output Differential (V) Output Voltage (V)

Output Voltage (V)

TL/H/7138±13

Quiescent Current

Output Voltage Noise

TL/H/7138±14

Line Transient Response

Load Transient Response

TL/H/7138±15

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