LM105.PDF

June 1999

LM105/LM305/LM305A

Voltage Regulators

General Description

The LM105 series are positive voltage regulators similar to

the LM100, except that an extra gain stage has been added

for improved regulation. A redesign of the biasing circuitry re-

moves any minimum load current requirement and at the

same time reduces standby current drain, permitting higher

voltage operation. They are direct, plug-in replacements for

the LM100 in both linear and switching regulator circuits with

output voltages greater than 4.5V. Important characteristics

of the circuits are:

• Output voltage adjustable from 4.5V to 40V

• Output currents in excess of 10A possible by adding ex-

ternal transistors

• Load regulation better than 0.1%, full load with current

limiting

• DC line regulation guaranteed at 0.03%/V

• Ripple rejection on 0.01%V

• 45 mA output current without external pass transistor

(LM305A)

Like the LM100, they also feature fast response to both load

and line transients, freedom from oscillations with varying re-

sistive and reactive loads and the ability to start reliably on

any load within rating. The circuits are built on a single silicon

chip and are supplied in a TO-99 metal can.

The LM105 is specified for operation for −55˚C

T A

+125˚C, and the LM305/LM305A is specified for 0˚C £ T A

+70˚C.

Schematic and Connection Diagrams

Metal Can Package

DS007755-3

Top View

Order Number LM105H, LM105H/883,

SMD #5962-8958801, LM305H or LM305AH

See NS Package Number H08C

DS007755-1

DS007755

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Absolute Maximum Ratings (Note 1)

If Military/Aerospace specified devices are required,

please contact the National Semiconductor Sales Office/

Distributors for availability and specifications.

(Note 5)

LM105

LM305

LM305A

Input Voltage

50V

40V

50V

Input-Output Differential

40V

Power Dissipation (Note 1)

800 mW

Operating Temperature Range

−55˚C to +125˚C

0˚C to +70˚C

Storage Temperature Range

−65˚C to +150˚C

65˚C to +150˚C

−65˚C to +150˚C

Lead Temperature (Soldering, 10 seconds)

300˚C

Electrical Characteristics (Note 2)

Parameter

Conditions

LM105

LM305

LM305A

Units

Min Typ Max Min Typ Max Min Typ Max

Input Voltage Range

8.5

Output Voltage Range

4.5

Input-Output Voltage

3.0

Differential

Load Regulation

R SC = 10 W ,T A = 25˚C

0.02 0.05

(Note 3)

R SC = 10 W ,T A = T A(MAX)

0.03

0.1

0.03

0.1

R SC = 10 W ,T A = T A(MIN)

0.03

0.1

0.03

0.1

I O

12 mA

I O

12 mA

R SC = 0

,T A = 25˚C

0.02

0.2

R SC = 0

,T A =70˚C

0.03

0.4

R SC = 0

,T A =0˚C

0.03

0.4

I O

45 mA

Line Regulation

T A = 25˚C

%/V

0˚C

T A

+70˚C

%/V

V IN −V OUT

5V, T A = 25˚C

0.025 0.06

0.025 0.06 %/V

V IN −V OUT

5V, T A = 25˚C

0.015 0.03

0.015 0.03 %/V

Temperature Stability

T A(MIN)

T A

T A(MAX)

0.3

1.0

0.3

1.0

0.3

1.0

Feedback Sense

Voltage

1.63

1.7

1.81 1.63

1.7

1.81 1.55

1.7

1.85

Output Noise Voltage

10 Hz

10 kHz

C REF = 0

0.005

C REF = 0.1 µF

0.002

Standby Current Drain V IN = 30V, T A = 25˚C

V IN = 40V

0.8

2.0

V IN = 50V

0.8

2.0

0.8

2.0

Current Limit

T A = 25˚C, R SC = 10

225 300

375 225 300

375

Sense Voltage

V OUT = 0V, (Note 4)

Long Term Stability

0.1

Ripple Rejection

C REF = 10 µF, f = 120 Hz

0.003

%/V

q JA

TO-99 Board Mount

230

˚C/W

in Still Air

q JA

TO-99 Board Mount in

˚C/W

400 LF/Min Air Flow

q JC

TO-99

˚C/W

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Electrical Characteristics (Note 2) (Continued)

Note 1: The maximum junction temperature of the LM105 and LM305A is 150˚C, and the LM305 is 85˚C. For operation at elevated temperatures, devices in the

H08C package must be derated based on a thermal resistance of 168˚C/W junction to ambient, or 25˚C/W junction to case. Peak dissipations to 1W are allowable

providing the dissipation rating is not exceeded with the power average over a five second interval for the LM105 and averaged over a two second interval for the

LM305.

Note 2: Unless otherwise specified, these specifications apply for temperatures within the operating temperature range, for input and output voltages within the

range given, and for a divider impedance seen by the feedback terminal of 2 k

Typical Performance Characteristics

Load Regulation

Current Limiting

Characteristics

DS007755-15

DS007755-16

DS007755-17

Current Limit Sense Voltage

Short Circuit Current

Optimum Divider Resistance

Values

DS007755-18

DS007755-19

DS007755-20

Minimum Input Voltage

Regulator Dropout Voltage

Supply Voltage Rejection

DS007755-21

DS007755-22

DS007755-23

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. Load and line regulation specifications are for a constant junction temperature. Tem-

perature drift effects must be taken into account separately when the unit is operating under conditions of high dissipation.

Note 3: The output currents given, as well as the load regulation, can be increased by the addition of external transistors. The improvement factor will be roughly

equal to the composite current gain of the added transistors.

Note 4: With no external pass transistor.

Note 5: Refer to RETS105X Drawing for military specifications for the LM105.