LM140K12P+ 概述
3-Terminal Positive Regulators 三端稳压器正
LM140K12P+ 数据手册
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PDF下载November 2004
LM340/LM78XX Series
3-Terminal Positive Regulators
General Description
The 5V, 12V, and 15V regulator options are available in the
steel TO-3 power package. The LM340A/LM340/LM78XXC
series is available in the TO-220 plastic power package, and
the LM340-5.0 is available in the SOT-223 package, as well
as the LM340-5.0 and LM340-12 in the surface-mount TO-
263 package.
The
LM140/LM340A/LM340/LM78XXC
monolithic
3-terminal positive voltage regulators employ internal
current-limiting, thermal shutdown and safe-area compensa-
tion, making them essentially indestructible. If adequate heat
sinking is provided, they can deliver over 1.0A output cur-
rent. They are intended as fixed voltage regulators in a wide
range of applications including local (on-card) regulation for
elimination of noise and distribution problems associated
with single-point regulation. In addition to use as fixed volt-
age regulators, these devices can be used with external
components to obtain adjustable output voltages and cur-
rents.
Features
n Complete specifications at 1A load
n Output voltage tolerances of 2% at Tj = 25˚C and 4%
over the temperature range (LM340A)
n Line regulation of 0.01% of VOUT/V of ∆VIN at 1A load
(LM340A)
n Load regulation of 0.3% of VOUT/A (LM340A)
n Internal thermal overload protection
n Internal short-circuit current limit
n Output transistor safe area protection
n P+ Product Enhancement tested
Considerable effort was expended to make the entire series
of regulators easy to use and minimize the number of exter-
nal components. It is not necessary to bypass the output,
although this does improve transient response. Input by-
passing is needed only if the regulator is located far from the
filter capacitor of the power supply.
Typical Applications
Fixed Output Regulator
Adjustable Output Regulator
00778102
00778101
>
= 5V + (5V/R1 + I ) R2 5V/R1 3 I ,
Q Q
V
OUT
*Required if the regulator is located far from the power supply filter.
load regulation (L ) ≈ [(R1 + R2)/R1] (L of LM340-5).
r
r
**Although no output capacitor is needed for stability, it does help transient
response. (If needed, use 0.1 µF, ceramic disc).
Comparison between SOT-223 and D-Pak (TO-252)
Packages
Current Regulator
00778103
00778138
Scale 1:1
∆I = 1.3 mA over line and load changes.
Q
© 2004 National Semiconductor Corporation
DS007781
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Ordering Information
Package
Temperature
Range
Part Number
Packaging Marking
Transport Media
NSC
Drawing
K02A
3-Lead TO-3
-55˚C to +125˚C
LM140K-5.0
LM140K-12
LM140K 5.0P+
LM140K 12P+
50 Per Tray
50 Per Tray
LM140K-15
LM140K 15P+
50 Per Tray
0˚C to +125˚C
0˚C to +125˚C
LM340K-5.0
LM340K 5.0 7805P+
LM340K 12 7812P+
LM340K 15 7815P+
LM340AT 5.0 P+
LM340T5 7805 P+
LM340T12 7812 P+
LM340T15 7815 P+
LM7808CT
50 Per Tray
LM340K-12
50 Per Tray
LM340K-15
50 Per Tray
3-lead TO-220
3-Lead TO-263
LM340AT-5.0
LM340T-5.0
45 Units/Rail
T03B
TS3B
45 Units/Rail
LM340T-12
45 Units/Rail
LM340T-15
45 Units/Rail
LM7808CT
45 Units/Rail
0˚C to +125˚C
LM340S-5.0
45 Units/Rail
LM340S-5.0 P+
LM340S-12 P+
LM340AS-5.0 P+
N00A
LM340SX-5.0
LM340S-12
500 Units Tape and Reel
45 Units/Rail
LM340SX-12
LM340AS-5.0
LM340ASX-5.0
LM340MP-5.0
LM340MPX-5.0
LM140KG-5 MD8
LM140KG-12 MD8
LM140KG-15 MD8
LM340-5.0 MDA
LM7808C MDC
500 Units Tape and Reel
45 Units/Rail
500 Units Tape and Reel
1k Units Tape and Reel
2k Units Tape and Reel
Waffle Pack or Gel Pack
Waffle Pack or Gel Pack
Waffle Pack or Gel Pack
Waffle Pack or Gel Pack
Waffle Pack or Gel Pack
4-Lead
0˚C to +125˚C
−55˚C to 125˚C
MP04A
SOT-223
Unpackaged
Die
DL069089
DL059093
DL059093
DI074056
DI074056
0˚C to +125˚C
Connection Diagrams
TO-3 Metal Can Package (K)
TO-220 Power Package (T)
00778112
00778111
Top View
See Package Number T03B
Bottom View
See Package Number K02A
TO-263 Surface-Mount Package (S)
3-Lead SOT-223
00778120
Top View
00778143
Top View
See Package Number TS3B
See Package Number MP04A
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2
Absolute Maximum Ratings (Note 1)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
TO-220 Package (T), TO-263
Package (S)
230˚C
2 kV
ESD Susceptibility (Note 3)
(Note 5)
Operating Conditions (Note 1)
Temperature Range (TA) (Note 2)
DC Input Voltage
35V
Internally Limited
150˚C
Internal Power Dissipation (Note 2)
Maximum Junction Temperature
Storage Temperature Range
Lead Temperature (Soldering, 10 sec.)
TO-3 Package (K)
LM140
−55˚C to +125˚C
0˚C to +125˚C
0˚C to +125˚C
LM340A, LM340
LM7808C
−65˚C to +150˚C
300˚C
LM340A Electrical Characteristics
IOUT = 1A, 0˚C ≤ TJ ≤ + 125˚C (LM340A) unless otherwise specified (Note 4)
Output Voltage
5V
12V
19V
15V
Symbol
VO
Input Voltage (unless otherwise noted)
10V
23V
Units
Parameter
Output Voltage
Conditions
Min Typ Max Min Typ Max Min Typ Max
TJ = 25˚C
4.9
4.8
5
5.1 11.75 12 12.25 14.7 15 15.3
5.2 11.5 12.5 14.4 15.6
V
V
PD ≤ 15W, 5 mA ≤ IO ≤ 1A
VMIN ≤ VIN ≤ VMAX
(7.5 ≤ VIN ≤ 20) (14.8 ≤ VIN ≤ 27) (17.9 ≤ VIN ≤ 30)
10 18 22
(7.5 ≤ VIN ≤ 20) (14.8 ≤ VIN ≤ 27) (17.9 ≤ VIN ≤ 30)
10 18 22
(7.5 ≤ VIN ≤ 20) (14.5 ≤ VIN ≤ 27) (17.5 ≤ VIN ≤ 30)
V
∆VO
Line Regulation IO = 500 mA
mV
V
∆VIN
TJ = 25˚C
∆VIN
3
4
4
mV
V
TJ = 25˚C
4
12
9
30
10
30
mV
mV
V
Over Temperature
∆VIN
(8 ≤ VIN ≤ 12)
(16 ≤ VIN ≤ 22)
(20 ≤ VIN ≤ 26)
∆VO
Load Regulation TJ = 25˚C
5 mA ≤ IO ≤ 1.5A
250 mA ≤ IO ≤ 750
mA
10
25
15
12
32
19
12
35
21
mV
mV
Over Temperature,
25
6
60
6
75
6
mV
mA
5 mA ≤ IO ≤ 1A
IQ
Quiescent
Current
TJ = 25˚C
Over Temperature
6.5
6.5
6.5
mA
mA
∆IQ
Quiescent
Current
5 mA ≤ IO ≤ 1A
0.5
0.5
0.5
Change
TJ = 25˚C, IO = 1A
VMIN ≤ VIN ≤ VMAX
IO = 500 mA
0.8
0.8
0.8
mA
V
(7.5 ≤ VIN ≤ 20) (14.8 ≤ VIN ≤ 27) (17.9 ≤ VIN ≤ 30)
0.8
(8 ≤ VIN ≤ 25)
40
0.8
0.8
mA
V
VMIN ≤ VIN ≤ VMAX
TA = 25˚C, 10 Hz ≤ f ≤ 100 kHz
(15 ≤ VIN ≤ 30) (17.9 ≤ VIN ≤ 30)
VN
Output Noise
Voltage
75
72
90
70
µV
Ripple Rejection TJ = 25˚C, f = 120 Hz, IO = 1A
or f = 120 Hz, IO = 500 mA,
Over Temperature,
68
68
80
61
61
60
60
dB
dB
VMIN ≤ VIN ≤ VMAX
(8 ≤ VIN ≤ 18)
(15 ≤ VIN ≤ 25)
(18.5 ≤ VIN
28.5)
2.0
≤
V
RO
Dropout Voltage TJ = 25˚C, IO = 1A
2.0
8
2.0
18
V
Output
f = 1 kHz
19
mΩ
Resistance
Short-Circuit
Current
TJ = 25˚C
2.1
1.5
1.2
A
3
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LM340A Electrical Characteristics (Continued)
IOUT = 1A, 0˚C ≤ TJ ≤ + 125˚C (LM340A) unless otherwise specified (Note 4)
Output Voltage
5V
12V
19V
15V
23V
Symbol
Input Voltage (unless otherwise noted)
10V
Units
A
Parameter
Conditions
Min Typ Max Min Typ Max Min Typ Max
Peak Output
Current
TJ = 25˚C
2.4
2.4
2.4
Average TC of
VO
Min, TJ = 0˚C, IO = 5 mA
TJ = 25˚C
−0.6
−1.5
−1.8
mV/˚C
VIN
Input Voltage
Required to
Maintain
7.5
14.5
17.5
V
Line Regulation
LM140 Electrical Characteristics (Note 4)
−55˚C ≤ TJ ≤ +150˚C unless otherwise specified
Output Voltage
5V
10V
12V
19V
15V
23V
Symbol
VO
Input Voltage (unless otherwise noted)
Units
Parameter
Conditions
TJ = 25˚C, 5 mA ≤ IO ≤ 1A
PD ≤ 15W, 5 mA ≤ IO ≤ 1A
VMIN ≤ VIN ≤ VMAX
Min Typ Max Min Typ Max Min Typ Max
Output Voltage
4.8
5
5.2 11.5
5.25 11.4
12 12.5 14.4 15 15.6
12.614.25 15.75
(18.5 ≤ VIN
V
V
V
4.75
(8 ≤ VIN ≤ 20)
(15.5 ≤ VIN ≤ 27)
≤
30)
∆VO
Line Regulation
IO = 500 mA TJ = 25˚C
3
50
4
120
4
150 mV
∆VIN
(7 ≤ VIN ≤ 25)
(14.5 ≤ VIN ≤ 30)
(17.5 ≤ VIN
≤
V
30)
−55˚C ≤ TJ ≤ +150˚C
50
120
150 mV
∆VIN
(8 ≤ VIN ≤ 20)
(15 ≤ VIN ≤ 27)
(18.5 ≤ VIN
≤
V
30)
IO ≤ 1A
TJ = 25˚C
50
120
150 mV
∆VIN
(7.5 ≤ VIN ≤ 20) (14.6 ≤ VIN ≤ 27)
(17.7 ≤ VIN
≤
V
30)
−55˚C ≤ TJ ≤ +150˚C
∆VIN
25
60
(16 ≤ VIN ≤ 22)
75 mV
(20 ≤ VIN ≤ 26)
(8 ≤ VIN ≤ 12)
V
∆VO
Load Regulation
TJ = 25˚C
5 mA ≤ IO ≤ 1.5A
250 mA ≤ IP ≤ 750
mA
10
50
25
12 120
60
12 150 mV
75 mV
−55˚C ≤ TJ ≤ +150˚C,
5 mA ≤ IO ≤ 1A
50
120
150 mV
IQ
Quiescent Current IO ≤ 1A
TJ = 25˚C
6
7
6
7
6
7
mA
mA
mA
−55˚C ≤ TJ ≤ +150˚C
∆IQ
Quiescent Current 5 mA ≤ IO ≤ 1A
0.5
0.5
0.5
Change
TJ = 25˚C, IO ≤ 1A
0.8
0.8
(15 ≤ VIN ≤ 27)
0.8 mA
VMIN ≤ VIN ≤ VMAX
(8 ≤ VIN ≤ 20)
(18.5 ≤ VIN
≤
V
30)
IO = 500 mA, −55˚C ≤ TJ ≤ +150˚C
VMIN ≤ VIN ≤ VMAX
0.8
0.8
(15 ≤ VIN ≤ 30)
0.8 mA
(8 ≤ VIN ≤ 25)
(18.5 ≤ VIN
≤
V
30)
VN
Output Noise
Voltage
TA = 25˚C, 10 Hz ≤ f ≤ 100 kHz
40
75
90
µV
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4
LM140 Electrical Characteristics (Note 4) (Continued)
−55˚C ≤ TJ ≤ +150˚C unless otherwise specified
Output Voltage
5V
10V
12V
19V
15V
23V
Symbol
Input Voltage (unless otherwise noted)
Units
Parameter
Conditions
Min Typ Max Min Typ Max Min Typ Max
Ripple Rejection
IO ≤ 1A, TJ = 25˚C
68 80
61
72
60 70
dB
dB
V
or
f = 120 Hz
IO ≤ 500 mA,
−55˚C ≤ TJ ≤+150˚C
68
61
60
VMIN ≤ VIN ≤ VMAX
(8 ≤ VIN ≤ 18)
(15 ≤ VIN ≤ 25)
(18.5 ≤ VIN
28.5)
2.0
≤
RO
Dropout Voltage
TJ = 25˚C, IO = 1A
2.0
8
2.0
18
V
mΩ
A
Output Resistance f = 1 kHz
19
Short-Circuit
Current
TJ = 25˚C
2.1
1.5
1.2
Peak Output
Current
TJ = 25˚C
2.4
2.4
2.4
A
Average TC of
VOUT
0˚C ≤ TJ ≤ +150˚C, IO = 5 mA
TJ = 25˚C, IO ≤ 1A
−0.6
−1.5
−1.8
mV/˚C
VIN
Input Voltage
Required to
Maintain
7.5
14.6
17.7
V
Line Regulation
LM340 Electrical Characteristics (Note 4)
0˚C ≤ TJ ≤ +125˚C unless otherwise specified
Output Voltage
5V
12V
19V
15V
23V
Symbol
VO
Input Voltage (unless otherwise noted)
10V
Units
Parameter
Conditions
TJ = 25˚C, 5 mA ≤ IO ≤ 1A
PD ≤ 15W, 5 mA ≤ IO ≤ 1A
VMIN ≤ VIN ≤ VMAX
Min Typ Max Min Typ Max Min Typ Max
Output Voltage
4.8
5
5.2 11.5 12 12.5 14.4 15 15.6
5.25 11.4 12.6 14.25 15.75
(17.5 ≤ VIN ≤ 30)
V
V
V
4.75
(7.5 ≤ VIN ≤ 20)
(14.5 ≤ VIN ≤
27)
∆VO
Line Regulation
IO = 500 mA TJ = 25˚C
3
50
4
120
4
150 mV
∆VIN
(7 ≤ VIN ≤ 25)
(14.5 ≤ VIN
≤
(17.5 ≤ VIN ≤ 30)
V
30)
0˚C ≤ TJ ≤ +125˚C
50
(8 ≤ VIN ≤ 20)
50
120
(15 ≤ VIN ≤ 27) (18.5 ≤ VIN ≤ 30)
120 150 mV
150 mV
∆VIN
V
IO ≤ 1A
TJ = 25˚C
∆VIN
(7.5 ≤ VIN ≤ 20)
(14.6 ≤ VIN
27)
≤
(17.7 ≤ VIN ≤ 30)
V
0˚C ≤ TJ ≤ +125˚C
∆VIN
25
60
75
mV
V
(8 ≤ VIN ≤ 12)
(16 ≤ VIN ≤ 22) (20 ≤ VIN ≤ 26)
∆VO
Load Regulation
TJ = 25˚C
5 mA ≤ IO ≤ 1.5A
250 mA ≤ IO ≤ 750 mA
10
50
25
50
12 120
60
12 150 mV
75 mV
150 mV
5 mA ≤ IO ≤ 1A, 0˚C ≤ TJ ≤
120
+125˚C
IQ
Quiescent Current
IO ≤ 1A
TJ = 25˚C
8
8
8
mA
mA
mA
mA
0˚C ≤ TJ ≤ +125˚C
8.5
8.5
8.5
∆IQ
Quiescent Current
Change
5 mA ≤ IO ≤ 1A
0.5
0.5
0.5
TJ = 25˚C, IO ≤ 1A
1.0
1.0
1.0
5
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LM340 Electrical Characteristics (Note 4) (Continued)
0˚C ≤ TJ ≤ +125˚C unless otherwise specified
Output Voltage
5V
10V
12V
19V
15V
23V
Symbol
Input Voltage (unless otherwise noted)
Units
Parameter
Conditions
VMIN ≤ VIN ≤ VMAX
Min Typ Max Min Typ Max Min Typ Max
(7.5 ≤ VIN ≤ 20)
(14.8 ≤ VIN
≤
(17.9 ≤ VIN ≤ 30)
V
27)
IO ≤ 500 mA, 0˚C ≤ TJ ≤ +125˚C
VMIN ≤ VIN ≤ VMAX
1.0
1.0
1.0
mA
V
(7 ≤ VIN ≤ 25)
(14.5 ≤ VIN
≤
(17.5 ≤ VIN ≤ 30)
30)
VN
Output Noise
Voltage
TA = 25˚C, 10 Hz ≤ f ≤ 100 kHz
40
75
90
µV
dB
dB
V
Ripple Rejection
IO ≤ 1A, TJ =
25˚C
62
62
80
55
55
72
54
54
70
f = 120 Hz
or IO ≤ 500 mA,
0˚C ≤ TJ ≤ +125˚C
VMIN ≤ VIN ≤ VMAX
(8 ≤ VIN ≤ 18)
(15 ≤ VIN ≤ 25)
(18.5 ≤ VIN
28.5)
2.0
≤
RO
Dropout Voltage
TJ = 25˚C, IO = 1A
f = 1 kHz
2.0
8
2.0
18
V
mΩ
A
Output Resistance
19
Short-Circuit Current TJ = 25˚C
2.1
2.4
1.5
2.4
1.2
Peak Output
Current
TJ = 25˚C
2.4
A
Average TC of VOUT 0˚C ≤ TJ ≤ +125˚C, IO = 5 mA
−0.6
7.5
−1.5
14.6
−1.8
mV/˚C
V
VIN
Input Voltage
Required to
Maintain
TJ = 25˚C, IO ≤ 1A
17.7
Line Regulation
Note 1: Absolute Maximum Ratings are limits beyond which damage to the device may occur. Operating Conditions are conditions under which the device functions
but the specifications might not be guaranteed. For guaranteed specifications and test conditions see the Electrical Characteristics.
Note 2: The maximum allowable power dissipation at any ambient temperature is a function of the maximum junction temperature for operation (T
= 125˚C or
JMAX
150˚C), the junction-to-ambient thermal resistance (θ ), and the ambient temperature (T ). P
= (T − T )/θ . If this dissipation is exceeded, the die
JMAX A JA
JA
A
DMAX
temperature will rise above T
and the electrical specifications do not apply. If the die temperature rises above 150˚C, the device will go into thermal shutdown.
JMAX
For the TO-3 package (K, KC), the junction-to-ambient thermal resistance (θ ) is 39˚C/W. When using a heatsink, θ is the sum of the 4˚C/W junction-to-case
JA
JA
thermal resistance (θ ) of the TO-3 package and the case-to-ambient thermal resistance of the heatsink. For the TO-220 package (T), θ is 54˚C/W and θ is
JC
JA
JC
4˚C/W. If SOT-223 is used, the junction-to-ambient thermal resistance is 174˚C/W and can be reduced by a heatsink (see Applications Hints on heatsinking).
If the TO-263 package is used, the thermal resistance can be reduced by increasing the PC board copper area thermally connected to the package: Using 0.5 square
inches of copper area, θ is 50˚C/W; with 1 square inch of copper area, θ is 37˚C/W; and with 1.6 or more inches of copper area, θ is 32˚C/W.
JA
JA
JA
Note 3: ESD rating is based on the human body model, 100 pF discharged through 1.5 kΩ.
Note 4: All characteristics are measured with a 0.22 µF capacitor from input to ground and a 0.1 µF capacitor from output to ground. All characteristics except noise
voltage and ripple rejection ratio are measured using pulse techniques (t ≤ 10 ms, duty cycle ≤ 5%). Output voltage changes due to changes in internal temperature
w
must be taken into account separately.
Note 5: Military datasheets are available upon request. At the time of printing, the military datasheet specifications for the LM140K-5.0/883, LM140K-12/883, and
LM140K-15/883 complied with the min and max limits for the respective versions of the LM140. The LM140H and LM140K may also be procured as JAN devices
on slash sheet JM38510/107.
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6
LM7808C
Electrical Characteristics
0˚C ≤ TJ ≤ +150˚C, VI = 14V, IO = 500 mA, CI = 0.33 µF, CO = 0.1 µF, unless otherwise specified
Symbol
Parameter
Conditions (Note 6)
LM7808C
Typ
8.0
Units
Min
Max
8.3
160
80
VO
Output Voltage
TJ = 25˚C
TJ = 25˚C
7.7
V
∆VO
Line Regulation
Load Regulation
10.5V ≤ VI ≤ 25V
6.0
mV
11.0V ≤ VI ≤ 17V
5.0 mA ≤ IO ≤ 1.5A
250 mA ≤ IO ≤ 750
mA
2.0
∆VO
TJ = 25˚C
12
160
80
mV
4.0
VO
IQ
Output Voltage
Quiescent Current
Quiescent
11.5V ≤ VI ≤ 23V, 5.0 mA ≤ IO ≤ 1.0A, P ≤ 15W
TJ = 25˚C
7.6
56
8.4
8.0
1.0
0.5
V
4.3
mA
mA
∆IQ
With Line
With Load
11.5V ≤ VI ≤ 25V
Current Change
Noise
5.0 mA ≤ IO ≤ 1.0A
VN
TA = 25˚C, 10 Hz ≤ f ≤ 100 kHz
f = 120 Hz, IO = 350 mA, TJ = 25˚C
IO = 1.0A, TJ = 25˚C
f = 1.0 kHz
52
72
µV
dB
∆VI/∆VO Ripple Rejection
VDO
RO
Dropout Voltage
2.0
16
V
Output Resistance
mΩ
A
IOS
Output Short Circuit Current
Peak Output Current
TJ = 25˚C, VI = 35V
TJ = 25˚C
0.45
2.2
0.8
IPK
A
∆VO/∆T
Average Temperature
IO = 5.0 mA
mV/˚C
Coefficient of Output Voltage
Note 6: All characteristics are measured with a 0.22 µF capacitor from input to ground and a 0.1 µF capacitor from output to ground. All characteristics except noise
voltage and ripple rejection ratio are measured using pulse techniques (t ≤ 10 ms, duty cycle ≤ 5%). Output voltage changes due to changes in internal temperature
w
must be taken into account separately.
7
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Typical Performance Characteristics
Maximum Average Power Dissipation
Maximum Average Power Dissipation
00778122
00778123
Maximum Power Dissipation (TO-263)
(See Note 2)
Output Voltage (Normalized to 1V at TJ = 25˚C)
00778124
00778125
Note: Shaded area refers to LM340A/LM340, LM7805C, LM7812C and
LM7815C.
Ripple Rejection
Ripple Rejection
00778126
00778127
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8
Typical Performance Characteristics (Continued)
Output Impedance
Dropout Characteristics
00778129
00778128
Quiescent Current
Peak Output Current
00778131
00778130
Note: Shaded area refers to LM340A/LM340, LM7805C, LM7812C and
LM7815C.
Dropout Voltage
Quiescent Current
00778132
Note: Shaded area refers to LM340A/LM340, LM7805C, LM7812C and
LM7815C.
00778133
9
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Line Regulation
Line Regulation
140AK-5.0, IOUT = 1A, TA = 25˚C
140AK-5.0, VIN = 10V, TA = 25˚C
00778106
00778105
Equivalent Schematic
00778107
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10
Application Hints
The LM340/LM78XX series is designed with thermal protec-
tion, output short-circuit protection and output transistor safe
area protection. However, as with any IC regulator, it be-
comes necessary to take precautions to assure that the
regulator is not inadvertently damaged. The following de-
scribes possible misapplications and methods to prevent
damage to the regulator.
SHORTING THE REGULATOR INPUT
When using large capacitors at the output of these regula-
tors, a protection diode connected input to output (Figure 1)
may be required if the input is shorted to ground. Without the
protection diode, an input short will cause the input to rapidly
approach ground potential, while the output remains near
the initial VOUTbecause of the stored charge in the large
output capacitor. The capacitor will then discharge through a
large internal input to output diode and parasitic transistors.
If the energy released by the capacitor is large enough, this
diode, low current metal and the regulator will be destroyed.
The fast diode in Figure 1 will shunt most of the capacitors
discharge current around the regulator. Generally no protec-
tion diode is required for values of output capacitance ≤ 10
µF.
00778108
FIGURE 1. Input Short
RAISING THE OUTPUT VOLTAGE ABOVE THE INPUT
VOLTAGE
Since the output of the device does not sink current, forcing
the output high can cause damage to internal low current
paths in a manner similar to that just described in the “Short-
ing the Regulator Input” section.
00778109
FIGURE 2. Regulator Floating Ground
REGULATOR FLOATING GROUND (Figure 2)
When the ground pin alone becomes disconnected, the
output approaches the unregulated input, causing possible
damage to other circuits connected to VOUT. If ground is
reconnected with power “ON”, damage may also occur to the
regulator. This fault is most likely to occur when plugging in
regulators or modules with on card regulators into powered
up sockets. Power should be turned off first, thermal limit
ceases operating, or ground should be connected first if
power must be left on.
TRANSIENT VOLTAGES
If transients exceed the maximum rated input voltage of the
device, or reach more than 0.8V below ground and have
sufficient energy, they will damage the regulator. The solu-
tion is to use a large input capacitor, a series input break-
down diode, a choke, a transient suppressor or a combina-
tion of these.
00778110
FIGURE 3. Transients
When a value for θ(H–A) is found using the equation shown,
a heatsink must be selected that has a value that is less than
or equal to this number.
θ(H–A) is specified numerically by the heatsink manufacturer
in this catalog, or shown in a curve that plots temperature
rise vs power dissipation for the heatsink.
11
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Application Hints (Continued)
HEATSINKING TO-263 AND SOT-223 PACKAGE PARTS
Figures 6, 7 show the information for the SOT-223 package.
Figure 6 assumes a θ(J–A) of 74˚C/W for 1 ounce copper and
51˚C/W for 2 ounce copper and a maximum junction tem-
perature of 125˚C.
Both the TO-263 (“S”) and SOT-223 (“MP”) packages use a
copper plane on the PCB and the PCB itself as a heatsink.
To optimize the heat sinking ability of the plane and PCB,
solder the tab of the plane.
shows for the TO-263 the measured values of θ(J–A) for
different copper area sizes using a typical PCB with 1 ounce
copper and no solder mask over the copper area used for
heatsinking.
00778141
FIGURE 6. θ(J–A) vs Copper (2 ounce) Area
for the SOT-223 Package
00778139
FIGURE 4. θ(J–A) vs Copper (1 ounce)
Area for the TO-263 Package
As shown in the figure, increasing the copper area beyond 1
square inch produces very little improvement. It should also
be observed that the minimum value of θ(J–A) for the TO-263
package mounted to a PCB is 32˚C/W.
As a design aid, Figure 5 shows the maximum allowable
power dissipation compared to ambient temperature for the
TO-263 device (assuming θ(J–A) is 35˚C/W and the maxi-
mum junction temperature is 125˚C).
00778142
FIGURE 7. Maximum Power Dissipation vs
TAMB for the SOT-223 Package
Please see AN-1028 for power enhancement techniques to
be used with the SOT-223 package.
00778140
FIGURE 5. Maximum Power Dissipation vs
TAMB for the TO-263 Package
www.national.com
12
Typical Applications
Fixed Output Regulator
00778113
Note: Bypass capacitors are recommended for optimum stability and transient response, and should be located as close as possible to the regulator.
High Input Voltage Circuits
00778114
00778115
High Current Voltage Regulator
00778116
13
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Typical Applications (Continued)
High Output Current, Short Circuit Protected
00778117
Positive and Negative Regulator
00778118
www.national.com
14
Physical Dimensions inches (millimeters)
unless otherwise noted
TO-3 Metal Can Package (K)
NS Package Number K02A
TO-263 Surface-Mount Package (S)
NS Package Number TS3B
15
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Physical Dimensions inches (millimeters) unless otherwise noted (Continued)
TO-220 Power Package (T)
NS Package Number T03B
3-Lead SOT-223 Package
NS Package Number MP04A
www.national.com
16
Notes
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.
For the most current product information visit us at www.national.com.
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 AND GENERAL COUNSEL OF NATIONAL SEMICONDUCTOR
CORPORATION. As used herein:
1. Life support devices or systems are devices or systems
which, (a) are intended for surgical implant into the body, or
(b) support or sustain life, and 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 safety or effectiveness.
BANNED SUBSTANCE COMPLIANCE
National Semiconductor certifies that the products and packing materials meet the provisions of the Customer Products Stewardship
Specification (CSP-9-111C2) and the Banned Substances and Materials of Interest Specification (CSP-9-111S2) and contain no ‘‘Banned
Substances’’ as defined in CSP-9-111S2.
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