LM78M12CT [NSC]
3-Terminal Positive Voltage Regulators; 3端子正电压稳压器
| 型号： | LM78M12CT |
| 厂家： | 
National Semiconductor |
| 描述： | 3-Terminal Positive Voltage Regulators |
| 文件： | 总11页 (文件大小：314K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
July 1999
LM341/LM78MXX Series
3-Terminal Positive Voltage Regulators
General Description
Features
n Output current in excess of 0.5A
n No external components
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.
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
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 de-
graded performance associated with single-point regulation.
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
© 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.
Storage Temperature Range
−65˚C to +150˚C
Operating Junction Temperature
Range
−40˚C to +125˚C
Internally Limited
Power Dissipation (Note 2)
Input Voltage
Lead Temperature (Soldering, 10 seconds)
5V ≤ VO ≤ 15V
35V
TO-39 Package (H)
TO-220 Package (T)
300˚C
260˚C
ESD Susceptibility
TBD
Electrical Characteristics
=
Limits in standard typeface are for TJ 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: VIN 10V, CIN 0.33 µF, CO 0.1 µF
Symbol
VO
Parameter
Output Voltage
Conditions
Min
4.8
Typ
5.0
5.0
Max
5.2
Units
=
IL 500 mA
V
5 mA ≤ IL ≤ 500 mA
4.75
5.25
PD ≤ 7.5W, 7.5V ≤ VIN ≤ 20V
=
VR LINE
Line Regulation
7.2V ≤ VIN ≤ 25V
IL 100 mA
50
100
100
10.0
0.5
mV
mA
=
IL 500 mA
VR LOAD
IQ
Load Regulation
5 mA ≤ IL ≤ 500 mA
=
Quiescent Current
IL 500 mA
4
∆IQ
Quiescent Current Change
5 mA ≤ IL ≤ 500 mA
=
7.5V ≤ VIN ≤ 25V, IL 500 mA
1.0
=
=
Vn
Output Noise Voltage
Ripple Rejection
f
f
10 Hz to 100 kHz
40
78
µV
dB
V
=
120 Hz, IL 500 mA
=
VIN
Input Voltage Required
to Maintain Line Regulation
Long Term Stability
IL 500 mA
7.2
=
∆VO
IL 500 mA
20
mV/khrs
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2
Electrical Characteristics
=
Limits in standard typeface are for TJ 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: VIN 19V, CIN 0.33 µF, CO 0.1 µF
Symbol
VO
Parameter
Output Voltage
Conditions
Min
11.5
11.4
Typ
12
Max
12.5
12.6
Units
=
IL 500 mA
V
5 mA ≤ IL ≤ 500 mA
12
PD ≤ 7.5W, 14.8V ≤ VIN ≤ 27V
=
VR LINE
Line Regulation
14.5V ≤ VIN ≤ 30V
IL 100 mA
120
240
240
10.0
0.5
mV
mA
=
IL 500 mA
VR LOAD
IQ
Load Regulation
5 mA ≤ IL ≤ 500 mA
=
Quiescent Current
IL 500 mA
4
∆IQ
Quiescent Current Change
5 mA ≤ IL ≤ 500 mA
=
14.8V ≤ VIN ≤ 30V, IL 500 mA
1.0
=
=
Vn
Output Noise Voltage
Ripple Rejection
f
f
10 Hz to 100 kHz
75
71
µV
dB
V
=
120 Hz, IL 500 mA
=
VIN
Input Voltage Required
to Maintain Line Regulation
Long Term Stability
IL 500 mA
14.5
=
∆VO
IL 500 mA
48
mV/khrs
LM341-15, LM78M15C
=
=
=
Unless otherwise specified: VIN 23V, CIN 0.33 µF, CO 0.1 µF
Symbol Parameter Conditions
VO Output Voltage
Min
14.4
Typ
15
Max
15.6
Units
=
IL 500 mA
V
5 mA ≤ IL ≤ 500 mA
14.25
15
15.75
PD ≤ 7.5W, 18V ≤ VIN ≤ 30V
=
VR LINE
Line Regulation
17.6V ≤ VIN ≤ 30V
IL 100 mA
150
300
300
10.0
0.5
mV
mA
=
IL 500 mA
VR LOAD
IQ
Load Regulation
5 mA ≤ IL ≤ 500 mA
=
Quiescent Current
IL 500 mA
4
∆IQ
Quiescent Current Change
5 mA ≤ IL ≤ 500 mA
=
18V ≤ VIN ≤ 30V, IL 500 mA
1.0
=
=
Vn
Output Noise Voltage
Ripple Rejection
f
f
10 Hz to 100 kHz
90
69
µV
dB
V
=
120 Hz, IL 500 mA
=
VIN
Input Voltage Required
to Maintain Line Regulation
Long Term Stability
IL 500 mA
17.6
=
∆VO
IL 500 mA
60
mV/khrs
Note 1: Absolute maximum ratings indicate limits beyond which damage to the component may occur. Electrical specifications do not apply when operating the de-
vice outside of its rated operating conditions.
Note 2: The typical thermal resistance of the three package types is:
=
=
=
T (TO-220) package: θ
60 ˚C/W, θ
5 ˚C/W
(JA)
(JC)
(JC)
=
H (TO-39) package: θ
120 ˚C/W, θ
18 ˚C/W
(JA)
=
=
10 ˚C/W
DT (TO-252) package: θ
92 ˚C/W, θ
(JA)
(JC)
3
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Schematic Diagram
DS010484-1
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4
Typical Performance Characteristics
Peak Output Current
Ripple Rejection
Dropout Voltage
Quiescent Current
DS010484-10
DS010484-11
Ripple Rejection
DS010484-12
DS010484-13
Output Voltage (Normalized
=
to 1V at TJ 25˚C)
DS010484-15
DS010484-14
5
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Typical Performance Characteristics (Continued)
Quiescent Current
Output Impedance
DS010484-16
DS010484-17
Line Transient Response
Load Transient Response
DS010484-7
DS010484-8
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 envi-
ronment. Below is a list of variables that may affect the ther-
mal resistance and in turn the need for a heatsink.
Design Considerations
The LM78MXX/LM341XX fixed voltage regulator series has
built-in thermal overload protection which prevents the de-
vice from being damaged due to excessive junction tem-
perature.
R
θJC(Component Variables) RθCA(Application Variables)
The regulators also contain internal short-circuit protection
which limits the maximum output current, and safe-area pro-
tection for the pass transistor which reduces the short-circuit
current as the voltage across the pass transistor is in-
creased.
Leadframe Size & Material
Mounting Pad Size, Material,
& Location
No. of Conduction Pins
Die Size
Placement of Mounting Pad
PCB Size & Material
Although the internal power dissipation is automatically lim-
ited, the maximum junction temperature of the device must
be kept below +125˚C in order to meet data sheet specifica-
tions. An adequate heatsink should be provided to assure
this limit is not exceeded under worst-case operating condi-
tions (maximum input voltage and load current) if reliable
performance is to be obtained).
Die Attach Material
Traces Length & Width
Molding Compound Size and Adjacent Heat Sources
Material
Volume of Air
Air Flow
Ambient Temperature
Shape of Mounting Pad
1.0 Heatsink Considerations
When an integrated circuit operates with appreciable cur-
rent, its junction temperature is elevated. It is important to
quantify its thermal limits in order to achieve acceptable per-
formance 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 envi-
ronment. A one-dimension steady-state model of conduction
heat transfer is demonstrated in The heat generated at the
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6
Design Considerations (Continued)
DS010484-23
DS010484-24
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
FIGURE 2. Power Dissipation Diagram
The next parameter which must be calculated is the maxi-
mum allowable temperature rise, TR(max):
=
θJA TR (max)/PD
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 maxi-
mum power dissipation and maximum ambient temperature
of the application. To determine if a heatsink is needed, the
power dissipated by the regulator, PD, must be calculated:
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 pack-
age, no heatsink is needed since the package alone will dis-
sipate enough heat to satisfy these requirements. If the cal-
culated value for θJA fall below these limits, a heatsink is
required.
As a design aid, Table 1 shows the value of the θJA of
TO-252 for different heatsink area. The copper patterns that
we used to measure these θJA are shown at the end of the
Application Note Section. reflects the same test results as
what are in the Table 1
=
IIN IL + IG
=
PD (VIN−VOUT) IL + VIN G
I
shows the voltages and currents which are present in the
circuit.
shows the maximum allowable power dissipation vs. ambi-
ent temperature for theTO-252 device. shows the maximum
allowable power dissipation vs. copper area (in2) for the
TO-252 device. Please see AN1028 for power enhancement
techniques to be used with TO-252 package.
TABLE 1. θJA Different Heatsink Area
Copper Area
Layout
Thermal Resistance
Top Sice (in2)*
Bottom Side (in2)
(θJA, ˚C/W) TO-252
1
2
0.0123
0.066
0.3
0
0
103
87
60
54
52
47
84
70
63
57
57
89
72
61
55
53
3
0
4
0.53
0.76
1
0
5
0
6
0
7
0
0.2
0.4
0.6
0.8
1
8
0
9
0
10
11
12
13
14
15
16
0
0
0.066
0.175
0.284
0.392
0.5
0.066
0.175
0.284
0.392
0.5
*
Tab of device attached to topside copper
7
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Design Considerations (Continued)
DS010484-21
FIGURE 5. Maximum Allowable Power Dissipation vs.
2oz. Copper Area for TO-252
DS010484-20
FIGURE 3. θJA vs. 2oz Copper Area for TO-252
Typical Application
DS010484-9
DS010484-22
*
Required if regulator input is more than 4 inches from input filter capacitor
(or if no input filter capacitor is used).
**
FIGURE 4. Maximum Allowable Power Dissipation vs.
Ambient Temperature for TO-252
Optional for improved transient response.
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8
Physical Dimensions inches (millimeters) unless otherwise noted
TO-39 Metal Can Package (H)
Order Number LM78M05CH, LM78M12CH or LM78M15CH
NS Package Number H03A
9
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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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10
Physical Dimensions inches (millimeters) unless otherwise noted (Continued)
TO-252
Order Number LM78M05CDT
NS Package Number TD03B
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