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%.
The LMS8117A series is available in SOT-223 and TO-252
D-PAK packages. A minimum of 10µF tantalum capacitor is
required at the output to improve the transient response and
stability.
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)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
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, 1.5kΩ in 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 100-200Ω. For example,
with R1 = 124Ω and 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 0.5Ω and less than 5Ω.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 0.05Ω resistance
between the regulator and load will have a load regulation
due to line resistance of 0.05Ω xI
L
. If R1 (=125Ω) is con-
nected near the load, the effective line resistance will be
0.05Ω (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
Under normal operation, the LMS8117A regulators do not
need any protection diode. With the adjustable device, the
internal resistance between the adjust and output terminals
limits the current. No diode is needed to divert the current
around the regulator even with capacitor on the adjust terminal. The adjust pin can take a transient signal of
±
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
When an integrated circuit operates with an appreciable
current, itsjunction 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-dimensional steady-state model of conduction heat transfer is demonstrated in
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.
The next parameter which must be calculated is the maximum allowable temperature rise, T
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)
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:
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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.
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Email: support@nsc.com
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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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