LM7912CT中文资料

LM7912CT中文资料
LM7912CT中文资料

TL H 7340LM79XX Series 3-Terminal Negative Regulators

November1994

LM79XX Series3-Terminal Negative Regulators

General Description

The LM79XX series of3-terminal regulators is available with

fixed output voltages of b5V b8V b12V and b15V

These devices need only one external component a com-

pensation capacitor at the output The LM79XX series is

packaged in the TO-220power package and is capable of

supplying1 5A of output current

These regulators employ internal current limiting safe area

protection and thermal shutdown for protection against vir-

tually all overload conditions

Low ground pin current of the LM79XX series allows output

voltage to be easily boosted above the preset value with a

resistor divider The low quiescent current drain of

these devices with a specified maximum change with line

and load ensures good regulation in the voltage boosted

mode

For applications requiring other voltages see LM137data

sheet

Features

Y Thermal short circuit and safe area protection

Y High ripple rejection

Y1 5A output current

Y4%tolerance on preset output voltage Connection Diagrams

TO-220Package

TL H 7340–14

Front View

Order Number LM7905CT LM7912CT or LM7915CT

See NS Package Number TO3B

Typical Applications

Fixed Regulator

TL H 7340–3

Required if regulator is separated from filter capacitor by

more than3 For value given capacitor must be solid

tantalum 25m F aluminum electrolytic may be substituted

Required for stability For value given capacitor must be

solid tantalum 25m F aluminum electrolytic may be substi-

tuted Values given may be increased without limit

For output capacitance in excess of100m F a high current

diode from input to output(1N4001 etc )will protect the

regulator from momentary input shorts

C1995National Semiconductor Corporation RRD-B30M115 Printed in U S A

Absolute Maximum Ratings (Note 1)

If Military Aerospace specified devices are required please contact the National Semiconductor Sales Office Distributors for availability and specifications Input Voltage (V o e b 5V)

b 25V (V o e b 12V and b 15V)

b 35V

Input-Output Differential (V o e b 5V)

25V (V o e b 12V and b 15V)30V

Power Dissipation (Note 2)

Internally Limited

Operating Junction Temperature Range 0 C to a 125 C

Storage Temperature Range

b 65 C to a 150 C Lead Temperature (Soldering 10se

c )

230 C

Electrical Characteristics Conditions unless otherwise noted I OUT e 500mA C IN e 2 2m F C OUT e 1m F

0 C s T J s a 125 C Power Dissipation s 1 5W

Part Number LM7905C

Units

Output Voltage

b 5V Input Voltage (unless otherwise specified)

b 10V

Symbol Parameter Conditions

Min

Typ

Max

V O

Output Voltage

T J e 25 C

b 4 8b 5 0

b 5 2V 5mA s I OUT s 1A b 4 75

b 5 25

V P s 15W

(b 20s V IN s b 7)V D V O

Line Regulation

T J e 25 C (Note 3)

8

50mV (b 25s V IN s b 7)

V 215

mV (b 12s V IN s b 8)

V D V O

Load Regulation

T J e 25 C (Note 3)5mA s I OUT s 1 5A

15100mV 250mA s I OUT s 750mA 550mV I Q Quiescent Current T J e 25 C 1

2mA D I Q

Quiescent Current With Line

0 5

mA Change

(b 25s V IN s b 7)

V With Load 5mA s I OUT s 1A

0 5

mA V n Output Noise Voltage T A e 25 C 10Hz s f s 100Hz 125

m V Ripple Rejection f e 120Hz

54

66

dB (b 18s V IN s b 8)

V Dropout Voltage

T J e 25 C I OUT e 1A 1 1V I OMAX

Peak Output Current T J e 25 C 2 2A Average Temperature I OUT e 5mA 0 4

mV C

Coefficient of 0C s T J s 100 C

Output Voltage

Typical Applications (Continued)

Variable Output

TL H 7340–2

Improves transient response and ripple rejection Do not increase beyond 50m F V OUT e V SET

R1a R2R2J

Select R2as follows

LM7905CT 300X LM7912CT 750X LM7915CT

1k

2

Electrical Characteristics (Continued)Conditions unless otherwise noted I OUT e 500mA C IN e 2 2m F C OUT e 1m F 0 C s T J s a 125 C Power Dissipation e 1 5W

Part Number LM7912C

LM7915C

Units

Output Voltage

b 12V b 15V Input Voltage (unless otherwise specified)

b 19V

b 23V

Symbol Parameter Conditions

Min

Typ Max Min Typ

Max

V O

Output Voltage

T J e 25 C

b 11 5b 12 0b 12 5b 14 4b 15 0b 15 6

V 5mA s I OUT s 1A b 11 4b 12 6

b 14 25b 15 75

V P s 15W

(b 27s V IN s b 14 5)(b 30s V IN s b 17 5)

V D V O

Line Regulation

T J e 25 C (Note 3)

580

5100

mV (b 30s V IN s b 14 5)

(b 30s V IN s b 17 5)

V 330350mV (b 22s V IN s b 16)

(b 26s V IN s b 20)

V D V O

Load Regulation

T J e 25 C (Note 3)

5mA s I OUT s 1 5A

1520015200mV 250mA s I OUT s 750mA 575575mV I Q Quiescent Current T J e 25 C 1 5

31 5

3mA D I Q

Quiescent Current With Line

0 5

0 5

mA Change

(b 30s V IN s b 14 5)

(b 30s V IN s b 17 5)

V With Load 5mA s I OUT s 1A

0 5

0 5

mA V n Output Noise Voltage T A e 25 C 10Hz s f s 100Hz 300

375

m V Ripple Rejection f e 120Hz

5470

5470

dB (b 25s V IN s b 15)

(b 30s V IN s b 17 5)

V Dropout Voltage

T J e 25 C I OUT e 1A 1 11 1V I OMAX

Peak Output Current T J e 25 C 2 2

2 2

A Average Temperature I OUT e 5mA b 0 8

b 1 0

mV C

Coefficient of 0C s T J s 100 C

Output Voltage

Note 1 Absolute Maximum Ratings indicate limits beyond which damage to the device may occur Operating Ratings indicate conditions for which the device is intended to be functional but do not guarantee Specific Performance limits For guaranteed specifications and test conditions see the Electrical Characteristics Note 2 Refer to Typical Performance Characteristics and Design Considerations for details

Note 3 Regulation is measured at a constant junction temperature by pulse testing with a low duty cycle Changes in output voltage due to heating effects must be taken into account

Typical Applications (Continued)

Dual Trimmed Supply

TL H 7340–4

3

Design Considerations

The LM79XX fixed voltage regulator series has thermal

overload protection from excessive power dissipation inter-

nal short circuit protection which limits the circuit’s maxi-

mum current and output transistor safe-area compensation

for reducing the output current as the voltage across the

pass transistor is increased

Although the internal power dissipation is limited the junc-

tion temperature must be kept below the maximum speci-

fied temperature(125 C)in order to meet data sheet specifi-cations To calculate the maximum junction temperature or

heat sink required the following thermal resistance values

should be used

Typ Max Typ Max Package i JC i JC i JA i JA

C W C W C W C W

TO-2203 05 06040

P D MAX e T J Max b T A

i JC a i CA

or

T J Max T A

i JA

i CA e i CS a i SA(without heat sink) Solving for T J

T J e T A a P D(i JC a i CA)or

e T A a P D i JA(without heat sink)

Where

T J e Junction Temperature

T A e Ambient Temperature

P D e Power Dissipation

i JA e Junction-to-Ambient Thermal Resistance

i JC e Junction-to-Case Thermal Resistance

i CA e Case-to-Ambient Thermal Resistance

i CS e Case-to-Heat Sink Thermal Resistance

i SA e Heat Sink-to-Ambient Thermal Resistance

Typical Applications(Continued)

Bypass capacitors are necessary for stable operation of the

LM79XX series of regulators over the input voltage and out-

put current ranges Output bypass capacitors will improve

the transient response by the regulator

The bypass capacitors (2 2m F on the input 1 0m F on the

output)should be ceramic or solid tantalum which have

good high frequency characteristics If aluminum electrolyt-

ics are used their values should be10m F or larger The

bypass capacitors should be mounted with the shortest

leads and if possible directly across the regulator termi-

nals

High Stability1Amp Regulator

TL H 7340–5

Load and line regulation k0 01%temperature stability s0 2%

Determine Zener current

Solid tantalum

Select resistors to set output voltage 2ppm C tracking suggested

4

Typical Applications (Continued)

Current Source

I OUT e 1mA a

5V R1

TL H 7340–7

Light Controller Using Silicon Photo Cell

TL H 7340–8

Lamp brightness increase until i I e i Q ( 1mA)a 5V R1

Necessary only if raw supply filter capacitor is more than 2 from LM7905CT

5

Typical Applications(Continued)

High-Sensitivity Light Controller

TL H 7340–9

Lamp brightness increases until i i e5V R1(I i can be set as low as1m A)

Necessary only if raw supply filter capacitor is more than2 from LM7905

g15V 1Amp Tracking Regulators

TL H 7340–1

(b15)(a15)

Load Regulation at D I L e1A40mV2mV

Output Ripple C IN e3000m F I L e1A100m Vrms100m Vrms

Temperature Stability50mV50mV

Output Noise10Hz s f s10kHz150m Vrms150m Vrms

Resistor tolerance of R4and R5determine matching of(a)and(b)

outputs

Necessary only if raw supply filter capacitors are more than3 from regu-

lators

6

Schematic Diagrams

b 5V

T L H 7340–12

7

Schematic Diagrams (Continued)

b 12V a n d b 15V

T L H 7340–13

8

9

L M 79X X S e r i e s 3-T e r m i n a l N e g a t i v e R e g u l a t o r s

Physical Dimensions inches (millimeters)

TO-220Outline Package (T)

Order Number LM7905CT LM7912CT or LM7915CT

NS Package Number T03B

LIFE SUPPORT POLICY

NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF NATIONAL SEMICONDUCTOR CORPORATION As used herein 1 Life support devices or systems are devices or 2 A critical component is any component of a life systems which (a)are intended for surgical implant support device or system whose failure to perform can into the body or (b)support or sustain life and whose be reasonably expected to cause the failure of the life failure to perform when properly used in accordance support device or system or to affect its safety or with instructions for use provided in the labeling can effectiveness

be reasonably expected to result in a significant injury to the user

National Semiconductor National Semiconductor National Semiconductor National Semiconductor Corporation

Europe

Hong Kong Ltd

Japan Ltd

1111West Bardin Road

Fax (a 49)0-180-5308586

13th Floor Straight Block Tel 81-043-299-2309

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