Datasheet LMS8117AMPX-3.3, LMS8117AMP-ADJ, LMS8117AMP-1.8, LMS8117ADTX-ADJ, LMS8117ADTX-3.3 Datasheet (NSC)

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LMS8117A 1A Low-Dropout Linear Regulator
General Description
The LMS8117Ais a series of low dropout voltage regulators with a dropout of 1.2V at 1A of load current. It has the same pin-out as National Semiconductor’s industry standard LM317.
The LMS8117A is available in an adjustable version, which can set the output voltage from 1.25V to 13.8V with only two external resistors. In addition, it is also available in two fixed voltages, 1.8V and 3.3V.
The LMS8117Aoffers currentlimiting and thermal shutdown. Its circuit includes a zener trimmed bandgap reference to assure output voltage accuracy to within
±
1%.
Features
n Available in 1.8V, 3.3V, and Adjustable Versions n Space Saving SOT-223 and TO-252 Packages n Current Limiting and Thermal Protection n Output Current 1A n Temperature Range 0˚C to 125˚C n Line Regulation 0.2% (Max) n Load Regulation 0.4% (Max)
Applications
n Post Regulator for Switching DC/DC Converter n High Efficiency Linear Regulators n Battery Charger n Battery Powered Instrumentation
Typical Application
Fixed Output Regulator
DS101196-28
July 2001
LMS8117A 1A Low-Dropout Linear Regulator
© 2001 National Semiconductor Corporation DS101196 www.national.com
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Ordering Information
Package
Temperature Range
(T
J
)
Packaging Marking Transport Media
NSC
Drawing
0˚C to +125˚C
3-lead SOT-223
LMS8117AMP-ADJ LS0A 1k Tape and Reel MP04A
LMS8117AMPX-ADJ LS0A 2k Tape and Reel
LMS8117AMP-1.8 LS00 1k Tape and Reel
LMS8117AMPX-1.8 LS00 2k Tape and Reel
LMS8117AMP-3.3 LS01 1k Tape and Reel
LMS8117AMPX-3.3 LS01 2k Tape and Reel
3-lead TO-252 LMS8117ADT-ADJ LMS8117ADT-ADJ Rails TD03B
LMS8117ADTX-ADJ LMS8117ADT-ADJ 2.5k Tape and Reel
LMS8117ADT-1.8 LMS8117ADT-1.8 Rails
LMS8117ADTX-1.8 LMS8117ADT-1.8 2.5k Tape and Reel
LMS8117ADT-3.3 LMS8117ADT-3.3 Rails
LMS8117ADTX-3.3 LMS8117ADT-3.3 2.5k Tape and Reel
Connection Diagrams
SOT-223
DS101196-99
Top View
TO-252
DS101196-38
Top View
LMS8117A
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Block Diagram
DS101196-1
LMS8117A
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Absolute Maximum Ratings (Note 1)
Maximum Input Voltage (V
IN
to GND)
LMS8117A-ADJ, LMS8117A-1.8, LMS8117A-3.3 20V
Power Dissipation (Note 2) Internally Limited Junction Temperature (T
J
)
(Note 2)
150˚C
Storage Temperature Range -65˚C to 150˚C
Soldering Information
Infrared (20 sec) 235˚C
ESD Tolerance (Note 3) 2000V
Operating Ratings (Note 1)
Input Voltage (V
IN
to GND)
LMS8117A-ADJ, LMS8117A-1.8, LMS8117A-3.3 15V
Junction Temperature Range (T
J
)(Note 2)
0˚C to 125˚C
Electrical Characteristics
Typicals and limits appearing in normal type apply for TJ= 25˚C. Limits appearing in Boldface type apply over the entire junc­tion temperature range for operation, 0˚C to 125˚C.
Symbol Parameter Conditions
Min
(Note 5)
Typ
(Note 4)
Max
(Note 5)
Units
V
REF
Reference Voltage LMS8117A-ADJ
I
OUT
= 10mA, VIN-V
OUT
= 2V, TJ= 25˚C
10mA I
OUT
1A, 1.4V VIN-V
OUT
10V
1.238
1.225
1.250
1.250
1.262
1.270
V V
V
OUT
Output Voltage LMS8117A-1.8
I
OUT
= 10mA, VIN= 3.8V, TJ= 25˚C
0 I
OUT
1A, 3.2V VIN≤ 10V
1.782
1.746
1.800
1.800
1.818
1.854
V V
LMS8117A-3.3 I
OUT
= 10mA, VIN=5VTJ= 25˚C
0 I
OUT
1A, 4.75V VIN≤ 10V
3.267
3.235
3.300
3.300
3.333
3.365
V V
V
OUT
Line Regulation (Note 6)
LMS8117A-ADJ I
OUT
= 10mA, 1.5V VIN-V
OUT
13.75V 0.035 0.2 %
LMS8117A-1.8 I
OUT
= 0mA, 3.2V VIN≤ 10V
1 6 mV
LMS8117A-3.3 I
OUT
= 0mA, 4.75V VIN≤ 15V 1 6 mV
V
OUT
Load Regulation (Note 6)
LMS8117A-ADJ V
IN-VOUT
= 3V, 10mA I
OUT
1A 0.2 0.4 %
LMS8117A-1.8 V
IN
= 3.2V, 0 I
OUT
1A 1 10 mV
LMS8117A-3.3 V
IN
= 4.75V, 0 I
OUT
1A 1 10 mV
V
IN-VOUT
Dropout Voltage (Note 7)
I
OUT
= 100mA 1.1 1.15 V
I
OUT
= 500mA 1.15 1.2 V
I
OUT
= 1A 1.2 1.25 V
I
LIMIT
Current Limit VIN-V
OUT
= 5V, TJ= 25˚C 1.0 1.4 1.9 A
Minimum Load Current (Note 8)
LMS8117A-ADJ V
IN
= 15V 1.7 5 mA
Quiescent Current LMS8117A-1.8
V
IN
15V
5 10 mA
LMS8117A-3.3 V
IN
15V 5 10 mA
Thermal Regulation T
A
= 25˚C, 30ms Pulse 0.01 0.1 %/W
Ripple Regulation f
RIPPLE
= 120Hz, VIN-V
OUT
=3V
V
RIPPLE
=1V
PP
60 75 dB
Adjust Pin Current 60 120 µA Adjust Pin Current
Change
10mA I
OUT
1A,
1.4V V
IN-VOUT
10V 0.2 5 µA
LMS8117A
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Electrical Characteristics (Continued)
Typicals and limits appearing in normal type apply for TJ= 25˚C. Limits appearing in Boldface type apply over the entire junc­tion temperature range for operation, 0˚C to 125˚C.
Symbol Parameter Conditions
Min
(Note 5)
Typ
(Note 4)
Max
(Note 5)
Units
Temperature Stability 0.5 % Long Term Stability T
A
= 125˚C, 1000Hrs 0.3 %
RMS Output Noise (% of V
OUT
), 10Hz f 10kHz 0.003 %
Thermal Resistance Junction-to-Case
3-Lead SOT-223 3-Lead TO-252
15.0 10
˚C/W ˚C/W
Thermal Resistance Junction-to-Ambient (No heat sink; No air flow)
3-Lead SOT-223 3-Lead TO-252 (Note 9)
136
92
˚C/W ˚C/W
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 specific performance is not guaranteed. For guaranteed specifications and the test conditions, see the Electrical Characteristics.
Note 2: The maximum power dissipation is a function of T
J(MAX)
, θJA, and TA. The maximum allowable power dissipation at any ambient temperature is
P
D
=(T
J(MAX)–TA
)/θJA. All numbers apply for packages soldered directly into a PC board.
Note 3: For testing purposes, ESD was applied using human body model, 1.5kin series with 100pF. Note 4: Typical Values represent the most likely parametric norm. Note 5: All limits are guaranteed by testing or statistical analysis. Note 6: Load and line regulation are measured at constant junction room temperature. Note 7: The dropout voltage is the input/output differential at which the circuit ceases to regulate against further reduction in input voltage. It is measured when the
output voltage has dropped 100mV from the nominal value obtained at V
IN=VOUT
+1.5V.
Note 8: The minimum output current required to maintain regulation. Note 9: Minimum pad size of 0.038in
2
LMS8117A
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Typical Performance Characteristics
Dropout Voltage (VIN-V
OUT
)
DS101196-22
Short-Circuit Current
DS101196-23
Load Regulation
DS101196-24
LMS8117A-ADJ Ripple Rejection vs. Current
DS101196-6
LMS8117A-ADJ Ripple Rejection
DS101196-7
Temperature Stability
DS101196-25
LMS8117A
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Typical Performance Characteristics (Continued)
Adjust Pin Current
DS101196-26
LMS8117A-1.8 Load Transient Response
DS101196-8
LMS8117A-3.3 Load Transient Response
DS101196-9
LMS8117A-1.8 Line Transient Response
DS101196-10
LMS8117A-3.3 Line Transient Response
DS101196-11
LMS8117A
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APPLICATION NOTE
1.0 External Capacitors/Stability
1.1 Input Bypass Capacitor
An input capacitor is recommended. A 10µF tantalum on the input is a suitable input bypassing for almost all applications.
1.2 Adjust Terminal Bypass Capacitor
The adjust terminal can be bypassed to ground with a by­pass capacitor (C
ADJ
) to improve ripple rejection. This by­pass capacitor prevents ripple from being amplified as the output voltage is increased. At any ripple frequency, the impedance of the C
ADJ
should be less than R1 toprevent the
ripple from being amplified:
1/(2π*f
RIPPLE*CADJ
)<R1
The R1 is the resistor between the output and the adjust pin. Its value is normally in the range of 100-200. For example, with R1 = 124and f
RIPPLE
= 120Hz, the C
ADJ
should be
>
11µF.
1.3 Output Capacitor
The output capacitor is critical in maintaining regulator sta­bility, and must meet the required conditions for both mini­mum amount of capacitance and ESR (Equivalent Series Resistance). The minimum output capacitance required by the LMS8117A is 10µF, if a tantalum capacitor is used. Any increase of the output capacitance will merely improve the loop stability and transient response. The ESR of the output capacitor should be greater than 0.5and less than 5.In the case of the adjustable regulator, when the C
ADJ
is used,
a larger output capacitance (22µf tantalum) is required.
2.0 Output Voltage
The LMS8117A adjustable version develops a 1.25V refer­ence voltage, V
REF
, between the output and the adjust ter-
minal. As shown in
Figure 1
, this voltage is applied across resistor R1 to generate a constant current I1. The current I
ADJ
from the adjust terminal could introduce error to the output. Butsince it is very small (60µA) compared with the I1 and very constant with line and load changes, the error can be ignored. The constant current I1 then flows through the output set resistor R2 and sets the output voltage to the desired level.
For fixed voltage devices, R1 and R2 are integrated inside the devices.
3.0 Load Regulation
The LMS8117A regulates the voltage that appears between its output and ground pins, or between its output and adjust pins. In some cases, line resistances can introduce errors to the voltage across the load. To obtain the best load regula­tion, a few precautions are needed.
Figure 2
, shows a typical application using a fixed output regulator. The Rt1 and Rt2 are the line resistances. It is obvious that the V
LOAD
is less than the V
OUT
by the sum of the voltage drops along the line resistances. In this case, the load regulation seen at the R
LOAD
would be degraded from the data sheet specification. To improve this, the load should be tied directly to the output terminal on the positive side and directly tied to the ground terminal on the negative side.
When the adjustable regulator is used (
Figure 3
), the best performance is obtained with the positive side of the resistor R1 tied directly to the output terminal of the regulator rather than near the load.This eliminatesline drops from appearing effectively in series with the reference and degrading regu­lation. For example, a 5V regulator with 0.05resistance between the regulator and load will have a load regulation due to line resistance of 0.05xI
L
. If R1 (=125) is con-
nected near the load, the effective line resistance will be
0.05(1+R2/R1) or in this case, it is 4 times worse. In addition, the ground side of the resistor R2 can be returned near the ground of the load to provide remote ground sens­ing and improve load regulation.
DS101196-17
FIGURE 1. Basic Adjustable Regulator
DS101196-18
FIGURE 2. Typical Application using Fixed Output
Regulator
LMS8117A
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APPLICATION NOTE (Continued)
4.0 Protection Diodes
±
25V with
respect to the output voltage without damaging the device. When a output capacitor is connected to a regulator and the
input is shorted toground, the output capacitor will discharge into the output of the regulator. The discharge current de­pends on the value of the capacitor,the output voltage of the regulator, and rate of decrease of V
IN
. In the LMS8117A regulators, the internal diode between the output and input pins can withstand microsecond surge currents of 10A to 20A. With an extremely large output capacitor (1000 µF), and with input instantaneously shorted to ground, the regu­lator could be damaged.
In this case, an external diode is recommended between the output and input pins to protect the regulator, as shown in
Figure 4
.
5.0 Heatsink Requirements
Figure 5
. 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 Vari-
ables)
R
θCA
(Application Vari-
ables)
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
Ambient Temperatue
Shape of Mounting Pad
The LMS8117Aregulators haveinternal thermal shutdown to protect the device from over-heating. Under all possible operating conditions, the junction temperature of the LMS8117A must be within the range of 0˚C to 125˚C. A heatsink may be requireddepending 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=IL+IG
PD=(VIN-V
OUT)IL+VINIG
DS101196-19
FIGURE 3. Best Load Regulation using Adjustable
Output Regulator
DS101196-15
FIGURE 4. Regulator with Protection Diode
DS101196-37
FIGURE 5. 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
LMS8117A
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APPLICATION NOTE (Continued)
Figure 6
shows the voltages and currents which are present
in the circuit.
R
(max):
T
R
(max)=TJ(max)-TA(max)
where T
J
(max) is the maximum allowable junction tempera-
ture (125˚C), and T
A
(max) is the maximum ambient tem-
perature which will be encountered in the application. Using the calculated values for T
R
(max) and PD, the maxi­mum allowable value for the junction-to-ambient thermal resistance (θ
JA
) can be calculated:
θ
JA=TR
(max)/P
D
If the maximum allowable value for θJAis found to be 136˚C/W for SOT-223 package or 92˚C/W for TO-252 package, noheatsink is needed since the package alone will dissipate enough heat to satisfy these requirements. If the calculated value for θ
JA
falls below these limits, a heatsink is
required. As a design aid,
Table 1
shows the value of the θJAof SOT-223and TO-252for different heatsink area. The copper patterns that we used to measure these θ
JA
s are shown at
the end of the Application Notes Section.
Figure 7
and
Figure
8
reflects the same test results as what are in the
Table 1
.
Figure 9
and
Figure 10
shows the maximum allowable power dissipation vs. ambient temperature for the SOT-223 and TO-252 device.
Figure 11
and
Figure 12
shows the maxi-
mum allowable power dissipation vs. copper area (in
2
) for the SOT-223 and TO-252 devices. Please see AN1028 for power enhancement techniques to be used with SOT-223 and TO-252 packages.
TABLE 1. θ
JA
Different Heatsink Area
Layout Copper Area Thermal Resistance
Top Side (in
2
)* Bottom Side (in2)(θ
JA
,˚C/W) SOT-223 (θJA,˚C/W) TO-252 1 0.0123 0 136 103 2 0.066 0 123 87 3 0.3 0 84 60 4 0.53 0 75 54 5 0.76 0 69 52 61 0 66 47 7 0 0.2 115 84 8 0 0.4 98 70 9 0 0.6 89 63
10 0 0.8 82 57 11 0 1 79 57 12 0.066 0.066 125 89 13 0.175 0.175 93 72 14 0.284 0.284 83 61 15 0.392 0.392 75 55 16 0.5 0.5 70 53
*Tab of device attached to topside copper
DS101196-16
FIGURE 6. Power Dissipation Diagram
LMS8117A
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APPLICATION NOTE (Continued)
DS101196-13
FIGURE 7. θJAvs. 1oz Copper Area for SOT-223
DS101196-34
FIGURE 8. θJAvs. 2oz Copper Area for TO-252
DS101196-12
FIGURE 9. Maximum Allowable Power Dissipation vs.
Ambient Temperature for SOT-223
DS101196-36
FIGURE 10. Maximum Allowable Power Dissipation vs.
Ambient Temperature for TO-252
DS101196-14
FIGURE 11. Maximum Allowable Power Dissipation vs.
1oz Copper Area for SOT-223
DS101196-35
FIGURE 12. Maximum Allowable Power Dissipation vs.
2oz Copper Area for TO-252
LMS8117A
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APPLICATION NOTE (Continued)
DS101196-20
FIGURE 13. Top View of the Thermal Test Pattern in Actual Scale
LMS8117A
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APPLICATION NOTE (Continued)
DS101196-21
FIGURE 14. Bottom View of the Thermal Test Pattern in Actual Scale
LMS8117A
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Typical Application Circuits
DS101196-29
1.25V to 10V Adjustable Regulator with Improved Ripple Rejection
DS101196-27
5V Logic Regulator with Electronic Shutdown*
LMS8117A
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Physical Dimensions inches (millimeters) unless otherwise noted
3-Lead SOT-223
NS Package Number MP04A
LMS8117A
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Physical Dimensions inches (millimeters) unless otherwise noted (Continued)
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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.
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www.national.com
3-Lead TO-252
NS Package Number TD03B
LMS8117A 1A Low-Dropout Linear Regulator
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.
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