Datasheet LM78M12CMWC, LM78M12CH, LM78M12CT Datasheet (NSC)

LM341/LM78MXX Series
3-Terminal Positive Voltage Regulators

General Description

The LM341 and LM78MXX series of three-terminal positive
voltage regulators employ built-in current limiting, thermal
shutdown, and safe-operating area protection which makes
them virtually immune to damage from output overloads.

With adequate heatsinking, they can deliver in excess of

0.5A output current. Typical applications would include local
(on-card) regulators which can eliminate the noise and de­graded performance associated with single-point regulation.

Features

n Output current in excess of 0.5A
n No external components
n Internal thermal overload protection
n Internal short circuit current-limiting
n Output transistor safe-area compensation
n Available in TO-220, TO-39, and TO-252 D-PAK

packages

n Output voltages of 5V, 12V, and 15V

Connection Diagrams

TO-39 Metal Can Package (H)

DS010484-5

Bottom View

Order Number LM78M05CH, LM78M12CH or LM78M15CH

See NS Package Number H03A

TO-220 Power Package (T)

DS010484-6

Top View

Order Number LM341T-5.0, LM341T-12, LM341T-15, LM78M05CT, LM78M12CT or LM78M15CT

See NS Package Number T03B

TO-252

DS010484-19

Top View

Order Number LM78M05CDT

See NS Package Number TD03B

July 1999

LM341/LM78MXX Series 3-Terminal Positive Voltage Regulators

© 1999 National Semiconductor Corporation DS010484 www.national.com

Absolute Maximum Ratings (Note 1)

If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.

Lead Temperature (Soldering, 10 seconds)

TO-39 Package (H) 300˚C
TO-220 Package (T) 260˚C

Storage Temperature Range −65˚C to +150˚C
Operating Junction Temperature

Range −40˚C to +125˚C
Power Dissipation (Note 2) Internally Limited
Input Voltage

5V ≤ V

O

≤ 15V 35V

ESD Susceptibility TBD

Electrical Characteristics

Limits in standard typeface are for T

J

=

25˚C, and limits in boldface type apply over the −40˚C to +125˚C operating temperature
range. Limits are guaranteed by production testing or correlation techniques using standard Statistical Quality Control (SQC)
methods.

LM341-5.0, LM78M05C

Unless otherwise specified: V

IN

=

10V, C

IN

=

0.33 µF, C

O

=

0.1 µF

Symbol Parameter Conditions Min Typ Max Units

V

O

Output Voltage I

L

=

500 mA 4.8 5.0 5.2 V

5mA≤I

L

≤500 mA 4.75 5.0 5.25

P

D

≤ 7.5W, 7.5V ≤ VIN≤ 20V

V

R LINE

Line Regulation 7.2V ≤ VIN≤ 25V I

L

=

100 mA 50 mV

I

L

=

500 mA 100

V

R LOAD

Load Regulation 5 mA ≤ IL≤ 500 mA 100

I

Q

Quiescent Current I

L

=

500 mA 4 10.0 mA

∆I

Q

Quiescent Current Change 5 mA ≤ IL≤ 500 mA 0.5

7.5V ≤ V

IN

≤ 25V, I

L

=

500 mA 1.0

V

n

Output Noise Voltage f=10 Hz to 100 kHz 40 µV

Ripple Rejection f=120 Hz, I

L

=

500 mA

78 dB

V

IN

Input Voltage Required I

L

=

500 mA 7.2 V

to Maintain Line Regulation

∆V

O

Long Term Stability I

L

=

500 mA 20 mV/khrs

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Electrical Characteristics

Limits in standard typeface are for T

J

=

25˚C, and limits in boldface type apply over the −40˚C to +125˚C operating temperature
range. Limits are guaranteed by production testing or correlation techniques using standard Statistical Quality Control (SQC)
methods. (Continued)

LM341-12, LM78M12C

Unless otherwise specified: V

IN

=

19V, C

IN

=

0.33 µF, C

O

=

0.1 µF

Symbol Parameter Conditions Min Typ Max Units

V

O

Output Voltage I

L

=

500 mA 11.5 12 12.5 V

5mA≤I

L

≤500 mA 11.4 12 12.6

P

D

≤ 7.5W, 14.8V ≤ VIN≤ 27V

V

R LINE

Line Regulation 14.5V ≤ VIN≤ 30V I

L

=

100 mA 120 mV

I

L

=

500 mA 240

V

R LOAD

Load Regulation 5 mA ≤ IL≤ 500 mA 240

I

Q

Quiescent Current I

L

=

500 mA 4 10.0 mA

∆I

Q

Quiescent Current Change 5 mA ≤ IL≤ 500 mA 0.5

14.8V ≤ V

IN

≤ 30V, I

L

=

500 mA 1.0

V

n

Output Noise Voltage f=10 Hz to 100 kHz 75 µV

Ripple Rejection f=120 Hz, I

L

=

500 mA

71 dB

V

IN

Input Voltage Required I

L

=

500 mA 14.5 V

to Maintain Line Regulation

∆V

O

Long Term Stability I

L

=

500 mA 48 mV/khrs

LM341-15, LM78M15C

Unless otherwise specified: V

IN

=

23V, C

IN

=

0.33 µF, C

O

=

0.1 µF

Symbol Parameter Conditions Min Typ Max Units

V

O

Output Voltage I

L

=

500 mA 14.4 15 15.6 V

5mA≤I

L

≤500 mA 14.25 15 15.75

P

D

≤ 7.5W, 18V ≤ VIN≤ 30V

V

R LINE

Line Regulation 17.6V ≤ VIN≤ 30V I

L

=

100 mA 150 mV

I

L

=

500 mA 300

V

R LOAD

Load Regulation 5 mA ≤ IL≤ 500 mA 300

I

Q

Quiescent Current I

L

=

500 mA 4 10.0 mA

∆I

Q

Quiescent Current Change 5 mA ≤ IL≤ 500 mA 0.5

18V ≤ V

IN

≤ 30V, I

L

=

500 mA 1.0

V

n

Output Noise Voltage f=10 Hz to 100 kHz 90 µV
Ripple Rejection f=120 Hz, I

L

=

500 mA

69 dB

V

IN

Input Voltage Required I

L

=

500 mA 17.6 V

to Maintain Line Regulation

∆V

O

Long Term Stability I

L

=

500 mA 60 mV/khrs

Note 1: Absolute maximum ratings indicate limits beyond which damage to the component may occur. Electrical specificationsdonotapplywhenoperatingthe de­vice outside of its rated operating conditions.

Note 2: The typical thermal resistance of the three package types is:

T (TO-220) package: θ

(JA)

=

60 ˚C/W, θ

(JC)

=

5 ˚C/W

H (TO-39) package: θ

(JA)

=

120 ˚C/W, θ

(JC)

=

18 ˚C/W

DT (TO-252) package: θ

(JA)

=

92 ˚C/W, θ

(JC)

=

10 ˚C/W

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Schematic Diagram

DS010484-1

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Typical Performance Characteristics

Peak Output Current

DS010484-10

Ripple Rejection

DS010484-11

Ripple Rejection

DS010484-12

Dropout Voltage

DS010484-13

Output Voltage (Normalized
to 1V at T

J

=

25˚C)

DS010484-14

Quiescent Current

DS010484-15

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Typical Performance Characteristics (Continued)

Design Considerations

The LM78MXX/LM341XX fixed voltage regulator series has
built-in thermal overload protection which prevents the de­vice from being damaged due to excessive junction tem­perature.

The regulators also contain internal short-circuit protection
which limits the maximum output current, and safe-area pro­tection for the pass transistor which reduces the short-circuit
current as the voltage across the pass transistor is in­creased.

Although the internal power dissipation is automatically lim­ited, the maximum junction temperature of the device must
be kept below +125˚C in order to meet data sheet specifica­tions. An adequate heatsink should be provided to assure
this limit is not exceeded under worst-case operating condi­tions (maximum input voltage and load current) if reliable
performance is to be obtained).

1.0 Heatsink Considerations

When an integrated circuit operates with appreciable cur­rent, its junction temperature is elevated. It is important to
quantify its thermal limits in order to achieve acceptable per­formance and reliability. This limit is determined by summing
the individual parts consisting of a series of temperature
rises from the semiconductor junction to the operating envi­ronment. A one-dimension steady-state model of conduction
heat transfer is demonstrated in The heat generated at the

device junction flows through the die to the die attach pad,
through the lead frame to the surrounding case material, to
the printed circuit board, and eventually to the ambient envi­ronment. Below is a list of variables that may affect the ther­mal resistance and in turn the need for a heatsink.

R

θJC

(Component Variables) R

θCA

(Application Variables)

Leadframe Size & Material Mounting Pad Size, Material,

& Location
No. of Conduction Pins Placement of Mounting Pad
Die Size PCB Size & Material
Die Attach Material Traces Length & Width
Molding Compound Size and

Material

Adjacent Heat Sources

Volume of Air

Air Flow

Ambient Temperature

Shape of Mounting Pad

Quiescent Current

DS010484-16

Output Impedance

DS010484-17

Line Transient Response

DS010484-7

Load Transient Response

DS010484-8

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Design Considerations (Continued)

The LM78MXX/LM341XX regulators have internal thermal
shutdown to protect the device from over-heating. Under all
possible operating conditions, the junction temperature of
the LM78MXX/LM341XX must be within the range of 0˚C to
125˚C. A heatsink may be required depending on the maxi­mum power dissipation and maximum ambient temperature
of the application. To determine if a heatsink is needed, the
power dissipated by the regulator, P

D

, must be calculated:

I

IN

=

I

L+IG

P

D

=

(V

IN−VOUT)IL+VINIG

shows the voltages and currents which are present in the
circuit.

The next parameter which must be calculated is the maxi­mum allowable temperature rise, T

R

(max):

θ

JA

=

TR (max)/P

D

If the maximum allowable value for θJA˚C/w is found to be
≥60˚C/W for TO-220 package or ≥92˚C/W for TO-252 pack­age, no heatsink is needed since the package alone will dis­sipate enough heat to satisfy these requirements. If the cal­culated value for θ

JA

fall below these limits, a heatsink is

required.
As a design aid,

Table 1

shows the value of the θJAof
TO-252 for different heatsink area. The copper patterns that
we used to measure these θ

JA

are shown at the end of the
Application Note Section. reflects the same test results as
what are in the

Table 1

shows the maximum allowable power dissipation vs. ambi­ent temperature for theTO-252 device. shows the maximum
allowable power dissipation vs. copper area (in

2

) for the
TO-252 device. Please see AN1028 for power enhancement
techniques to be used with TO-252 package.

TABLE 1. θ

JA

Different Heatsink Area

Layout Copper Area Thermal Resistance

Top Sice (in

2

)* Bottom Side (in2)(θJA, ˚C/W) TO-252
1 0.0123 0 103
2 0.066 0 87
3 0.3 0 60
4 0.53 0 54
5 0.76 0 52
61047
7 0 0.2 84
8 0 0.4 70
9 0 0.6 63

10 0 0.8 57
11 0 1 57
12 0.066 0.066 89
13 0.175 0.175 72
14 0.284 0.284 61
15 0.392 0.392 55
16 0.5 0.5 53

*

Tab of device attached to topside copper

DS010484-23

FIGURE 1. Cross-sectional view of Integrated Circuit

Mounted on a printed circuit board. Note that the case

temperature is measured at the point where the leads

contact with the mounting pad surface

DS010484-24

FIGURE 2. Power Dissipation Diagram

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Design Considerations (Continued)

Typical Application

DS010484-20

FIGURE 3. θJAvs. 2oz Copper Area for TO-252

DS010484-22

FIGURE 4. Maximum Allowable Power Dissipation vs.

Ambient Temperature for TO-252

DS010484-21

FIGURE 5. Maximum Allowable Power Dissipation vs.

2oz. Copper Area for TO-252

DS010484-9

*

Required if regulator input is more than 4 inches from input filter capacitor

(or if no input filter capacitor is used).

**

Optional for improved transient response.

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Physical Dimensions inches (millimeters) unless otherwise noted

TO-39 Metal Can Package (H)

Order Number LM78M05CH, LM78M12CH or LM78M15CH

NS Package Number H03A

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Physical Dimensions inches (millimeters) unless otherwise noted (Continued)

TO-220 Power Package (T)

Order Number LM341T-5.0, LM341T-12, LM341T-15, LM78M05CT, LM78M12CT or LM78M15CT

NS Package Number T03B

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Physical Dimensions inches (millimeters) unless otherwise noted (Continued)

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whose failure to perform when properly used in
accordance with instructions for use provided in the
labeling, can be reasonably expected to result in a
significant injury to the user.

2. A critical component is any component of a life
support device or system whose failure to perform
can be reasonably expected to cause the failure of
the life support device or system, or to affect its
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www.national.com

TO-252

Order Number LM78M05CDT

NS Package Number TD03B

LM341/LM78MXX Series 3-Terminal Positive Voltage Regulators

National does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and National reserves the right at any time without notice to change said circuitry and specifications.