LM1117T-2.5 [TI]
800mA Low-Dropout Linear Regulator; 800毫安低压差线性稳压器
| 型号： | LM1117T-2.5 |
| 厂家： | 
TEXAS INSTRUMENTS |
| 描述： | 800mA Low-Dropout Linear Regulator |
| 文件： | 总25页 (文件大小：458K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
LM1117/LM1117I
800mA Low-Dropout Linear Regulator
General Description
Features
The LM1117 is a series of low dropout voltage regulators with
a dropout of 1.2V at 800mA of load current. It has the same
pin-out as National Semiconductor's industry standard
LM317.
Available in 1.8V, 2.5V, 2.85V, 3.3V, 5V, and Adjustable
●
Versions
Space Saving SOT-223 and LLP Packages
Current Limiting and Thermal Protection
Output Current
Line Regulation
Load Regulation
●
●
The LM1117 is available in an adjustable version, which can
set the output voltage from 1.25V to 13.8V with only two ex-
ternal resistors. In addition, it is also available in five fixed
voltages, 1.8V, 2.5V, 2.85V, 3.3V, and 5V.
800mA
0.2% (Max)
0.4% (Max)
●
●
●
●
Temperature Range
The LM1117 offers current limiting and thermal shutdown. Its
circuit includes a zener trimmed bandgap reference to assure
output voltage accuracy to within ±1%.
LM1117
LM1117I
0°C to 125°C
−40°C to 125°C
—
—
The LM1117 series is available in LLP, TO-263, SOT-223,
TO-220, and TO-252 D-PAK packages. A minimum of 10µF
tantalum capacitor is required at the output to improve the
transient response and stability.
Applications
2.85V Model for SCSI-2 Active Termination
Post Regulator for Switching DC/DC Converter
High Efficiency Linear Regulators
Battery Charger
●
●
●
●
●
Battery Powered Instrumentation
Typical Application
Active Terminator for SCSI-2 Bus
10091905
Fixed Output Regulator
10091928
PRODUCTION DATA information is current as of
publication date. Products conform to specifications per
the terms of the Texas Instruments standard warranty.
Production processing does not necessarily include
testing of all parameters.
100919 SNOS412L
Copyright © 1999-2012, Texas Instruments Incorporated
LM1117/LM1117I
Ordering Information
Package
Temperature Range
Part Number
Packaging Marking
Transport Media
NSC
Drawing
3-lead SOT-223
0°C to +125°C
LM1117MPX-ADJ
LM1117MPX-2.5
LM1117MPX-2.85
LM1117MPX-3.3
LM1117MPX-5.0
LM1117IMPX-ADJ
LM1117IMPX-3.3
LM1117IMPX-5.0
LM1117T-ADJ
N03A
N13A
Tape and Reel
Tape and Reel
Tape and Reel
Tape and Reel
Tape and Reel
Tape and Reel
Tape and Reel
Tape and Reel
Rails
MP04A
N04A
N05A
N06A
−40°C to +125°C
0°C to +125°C
N03B
N05B
N06B
3-lead TO-220
3-lead TO-252
LM1117T-ADJ
LM1117T-1.8
LM1117T-2.5
LM1117T-3.3
LM1117T-5.0
LM1117DT-ADJ
LM1117DT-1.8
LM1117DT-2.5
LM1117DT-3.3
LM1117DT-5.0
LM1117IDT-ADJ
LM1117IDT-3.3
LM1117IDT-5.0
1117ADJ
T03B
LM1117T-1.8
Rails
LM1117T-2.5
Rails
LM1117T-3.3
Rails
LM1117T-5.0
Rails
0°C to +125°C
LM1117DTX-ADJ
LM1117DTX-1.8
LM1117DTX-2.5
LM1117DTX-3.3
LM1117DTX-5.0
LM1117IDTX-ADJ
LM1117IDTX-3.3
LM1117IDTX-5.0
LM1117LDX-ADJ
LM1117LDX-1.8
LM1117LDX-5.0
LM1117ILDX-ADJ
LM1117ILDX-3.3
LM1117ILDX-5.0
LM1117SX-ADJ
LM1117SX-3.3
LM1117SX-5.0
Tape and Reel
Tape and Reel
Tape and Reel
Tape and Reel
Tape and Reel
Tape and Reel
Tape and Reel
Tape and Reel
Tape and Reel
Tape and Reel
Tape and Reel
Tape and Reel
Tape and Reel
Tape and Reel
Tape and Reel
Tape and Reel
Tape and Reel
TD03B
−40°C to +125°C
0°C to +125°C
−40°C to 125°C
0°C to +125°C
8-lead LLP
LDC08A
1117-18
1117-50
1117IAD
1117I33
1117I50
TO-263
LM1117SADJ
LM1117S3.3
LM1117S5.0
TS3B
2
Copyright © 1999-2012, Texas Instruments Incorporated
LM1117/LM1117I
Block Diagram
10091901
Connection Diagrams
SOT-223
10091904
Top View
TO-220
10091902
Top View
TO-252
10091938
Top View
Copyright © 1999-2012, Texas Instruments Incorporated
3
LM1117/LM1117I
TO-263
Top View10091944
10091945
Side View
LLP
10091946
When using the LLP package
Pins 2, 3 & 4 must be connected together and
Pins 5, 6 & 7 must be connected together
Top View
4
Copyright © 1999-2012, Texas Instruments Incorporated
LM1117/LM1117I
Absolute Maximum Ratings (Note 1)
If Military/Aerospace specified devices are required, please contact the Texas Instruments Sales Office/ Distributors for
availability and specifications.
Maximum Input Voltage (VIN to GND)
20V
Power Dissipation (Note 2)
Junction Temperature (TJ)
(Note 2)
Internally Limited
150°C
Storage Temperature Range
Lead Temperature
-65°C to 150°C
TO-220 (T) Package
SOT-223 (IMP) Package
ESD Tolerance (Note 3)
260°C, 10 sec
260°C, 4 sec
2000V
Operating Ratings (Note 1)
Input Voltage (VIN to GND)
15V
Junction Temperature Range (TJ)(Note 2)
LM1117
LM1117I
0°C to 125°C
−40°C to 125°C
LM1117 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.
Min
(Note 5)
Typ
(Note 4)
Max
(Note 5)
Symbol
Parameter
Conditions
Units
VREF
Reference Voltage
LM1117-ADJ
IOUT = 10mA, VIN-VOUT = 2V, TJ = 25°C
ꢀ
1.238
ꢀ
1.250
ꢀ
1.262
ꢀ
V
1.225
1.250
1.270
V
10mA ≤ IOUT ≤ 800mA, 1.4V ≤ VIN-VOUT
10V
≤
VOUT
Output Voltage
LM1117-1.8
IOUT = 10mA, VIN = 3.8V, TJ = 25°C
1.782
1.746
1.800
1.800
1.818
1.854
V
V
0 ≤ IOUT ≤ 800mA, 3.2V ≤ VIN ≤ 10V
LM1117-2.5
IOUT = 10mA, VIN = 4.5V, TJ = 25°C
2.475
2.450
2.500
2.500
2.525
2.550
V
V
0 ≤ IOUT ≤ 800mA, 3.9V ≤ VIN ≤ 10V
LM1117-2.85
IOUT = 10mA, VIN = 4.85V, TJ = 25°C
ꢀ
ꢀ
ꢀ
ꢀ
V
V
2.820
2.790
2.790
2.850
2.850
2.850
2.880
2.910
2.910
0 ≤ IOUT ≤ 800mA, 4.25V ≤ VIN ≤ 10V
0 ≤ IOUT ≤ 500mA, VIN = 4.10V
V
LM1117-3.3
IOUT = 10mA, VIN = 5V TJ = 25°C
ꢀ
3.267
ꢀ
3.300
ꢀ
3.333
ꢀ
V
3.235
3.300
3.365
V
0 ≤ IOUT ≤ 800mA, 4.75V≤ VIN ≤ 10V
LM1117-5.0
IOUT = 10mA, VIN = 7V, TJ = 25°C
ꢀ
4.950
ꢀ
5.000
ꢀ
5.050
ꢀ
V
4.900
5.000
5.100
V
0 ≤ IOUT ≤ 800mA, 6.5V ≤ VIN ≤ 12V
Copyright © 1999-2012, Texas Instruments Incorporated
5
LM1117/LM1117I
Min
(Note 5)
Typ
(Note 4)
Max
(Note 5)
Symbol
Parameter
Conditions
Units
Line Regulation
(Note 6)
LM1117-ADJ
ΔVOUT
ꢀ
0.035
ꢀ
0.2
ꢀ
%
IOUT = 10mA, 1.5V ≤ VIN-VOUT ≤ 13.75V
LM1117-1.8
1
1
6
6
mV
mV
IOUT = 0mA, 3.2V ≤ VIN ≤ 10V
LM1117-2.5
IOUT = 0mA, 3.9V ≤ VIN ≤ 10V
LM1117-2.85
ꢀ
ꢀ
ꢀ
1
6
mV
IOUT = 0mA, 4.25V ≤ VIN ≤ 10V
LM1117-3.3
ꢀ
ꢀ
ꢀ
1
6
mV
IOUT = 0mA, 4.75V ≤ VIN ≤ 15V
LM1117-5.0
ꢀ
ꢀ
ꢀ
1
10
mV
IOUT = 0mA, 6.5V ≤ VIN ≤ 15V
LM1117-ADJ
Load Regulation
(Note 6)
ΔVOUT
ꢀ
ꢀ
ꢀ
0.2
0.4
%
VIN-VOUT = 3V, 10 ≤ IOUT ≤ 800mA
LM1117-1.8
1
1
10
10
mV
mV
VIN = 3.2V, 0 ≤ IOUT ≤ 800mA
LM1117-2.5
VIN = 3.9V, 0 ≤ IOUT ≤ 800mA
LM1117-2.85
ꢀ
ꢀ
ꢀ
1
10
mV
VIN = 4.25V, 0 ≤ IOUT ≤ 800mA
LM1117-3.3
ꢀ
ꢀ
ꢀ
1
10
mV
VIN = 4.75V, 0 ≤ IOUT ≤ 800mA
LM1117-5.0
ꢀ
ꢀ
ꢀ
1
15
mV
VIN = 6.5V, 0 ≤ IOUT ≤ 800mA
IOUT = 100mA
VIN-V OUT Dropout Voltage
1.10
1.15
1.20
1200
1.20
1.25
1.30
1500
V
V
(Note 7)
IOUT = 500mA
IOUT = 800mA
V
ILIMIT
Current Limit
VIN-VOUT = 5V, TJ = 25°C
800
mA
Minimum Load Current LM1117-ADJ
ꢀ
1.7
ꢀ
5
ꢀ
mA
(Note 8)
VIN = 15V
Quiescent Current
LM1117-1.8
VIN ≤ 15V
5
10
mA
LM1117-2.5
5
10
mA
VIN ≤ 15V
LM1117-2.85
VIN ≤ 10V
ꢀ
5
ꢀ
10
ꢀ
mA
LM1117-3.3
ꢀ
ꢀ
ꢀ
5
10
mA
VIN ≤ 15V
LM1117-5.0
VIN ≤ 15V
ꢀ
5
ꢀ
10
ꢀ
mA
Thermal Regulation
Ripple Regulation
TA = 25°C, 30ms Pulse
0.01
75
0.1
%/W
dB
fRIPPLE =1 20Hz, VIN-VOUT = 3V VRIPPLE
1VPP
=
60
Adjust Pin Current
60
120
μA
Adjust Pin Current
Change
ꢀ
0.2
ꢀ
5
ꢀ
μA
10 ≤ IOUT≤ 800mA,
1.4V ≤ VIN-VOUT ≤ 10V
Temperature Stability
Long Term Stability
0.5
0.3
%
%
TA = 125°C, 1000Hrs
6
Copyright © 1999-2012, Texas Instruments Incorporated
LM1117/LM1117I
Min
(Note 5)
Typ
(Note 4)
Max
Units
Symbol
Parameter
Conditions
(Note 5)
RMS Output Noise
0.003
%
(% of VOUT), 10Hz ≤ f ≤10kHz
3-Lead SOT-223
Thermal Resistance
Junction-to-Case
15.0
3.0
10
°C/W
°C/W
°C/W
°C/W
°C/W
°C/W
°C/W
°C/W
3-Lead TO-220
3-Lead TO-252
Thermal Resistance
Junction-to-Ambient
(No air flow)
3-Lead SOT-223 (No heat sink)
3-Lead TO-220 (No heat sink)
3-Lead TO-252 (Note 9) (No heat sink)
3-Lead TO-263
136
79
92
55
8-Lead LLP(Note 10)
40
LM1117I 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, −40°C to 125°C.
Min
(Note 5)
Typ
(Note 4)
Max
(Note 5)
Symbol
Parameter
Conditions
Units
VREF
Reference Voltage
LM1117I-ADJ
IOUT = 10mA, VIN-VOUT = 2V, TJ = 25°C
ꢀ
1.238
ꢀ
1.250
ꢀ
1.262
ꢀ
V
1.200
1.250
1.290
V
10mA ≤ IOUT ≤ 800mA, 1.4V ≤ VIN-VOUT
10V
≤
VOUT
Output Voltage
LM1117I-3.3
IOUT = 10mA, VIN = 5V, TJ = 25°C
ꢀ
3.267
ꢀ
3.300
ꢀ
3.333
ꢀ
V
3.168
3.300
3.432
V
0 ≤ IOUT ≤ 800mA, 4.75V ≤ VIN ≤ 10V
LM1117I-5.0
IOUT = 10mA, VIN = 7V, TJ = 25°C
ꢀ
4.950
ꢀ
5.000
ꢀ
5.050
ꢀ
V
4.800
5.000
5.200
V
0 ≤ IOUT ≤ 800mA, 6.5V ≤ VIN ≤ 12V
LM1117I-ADJ
Line Regulation
(Note 6)
ΔVOUT
ꢀ
ꢀ
ꢀ
0.035
0.3
%
IOUT = 10mA, 1.5V ≤ VIN-VOUT ≤ 13.75V
LM1117I-3.3
ꢀ
ꢀ
ꢀ
1
10
mV
IOUT = 0mA, 4.75V ≤ VIN ≤ 15V
LM1117I-5.0
ꢀ
ꢀ
ꢀ
1
15
mV
IOUT = 0mA, 6.5V ≤ VIN ≤ 15V
LM1117I-ADJ
Load Regulation
(Note 6)
ΔVOUT
ꢀ
ꢀ
ꢀ
0.2
0.5
%
VIN-VOUT = 3V, 10 ≤ IOUT ≤ 800mA
LM1117I-3.3
ꢀ
ꢀ
ꢀ
1
15
mV
VIN = 4.75V, 0 ≤ IOUT ≤ 800mA
LM1117I-5.0
ꢀ
ꢀ
ꢀ
1
20
mV
VIN = 6.5V, 0 ≤ IOUT ≤ 800mA
IOUT = 100mA
VIN-V OUT Dropout Voltage
1.10
1.15
1.20
1200
1.30
1.35
1.40
1500
V
V
(Note 7)
IOUT = 500mA
IOUT = 800mA
V
ILIMIT
Current Limit
VIN-VOUT = 5V, TJ = 25°C
800
mA
Minimum Load Current LM1117I-ADJ
ꢀ
1.7
ꢀ
5
ꢀ
mA
(Note 8)
VIN = 15V
Quiescent Current
LM1117I-3.3
VIN ≤ 15V
ꢀ
5
ꢀ
15
ꢀ
mA
LM1117I-5.0
ꢀ
ꢀ
ꢀ
5
15
mA
VIN ≤ 15V
Thermal Regulation
TA = 25°C, 30ms Pulse
0.01
0.1
%/W
Copyright © 1999-2012, Texas Instruments Incorporated
7
LM1117/LM1117I
Min
(Note 5)
Typ
(Note 4)
Max
(Note 5)
Symbol
Parameter
Conditions
Units
Ripple Regulation
fRIPPLE =1 20Hz, VIN-VOUT = 3V VRIPPLE
1VPP
=
60
75
dB
Adjust Pin Current
60
120
μA
Adjust Pin Current
Change
ꢀ
0.2
ꢀ
10
ꢀ
μA
10 ≤ IOUT≤ 800mA,
1.4V ≤ VIN-VOUT ≤ 10V
Temperature Stability
Long Term Stability
RMS Output Noise
0.5
0.3
%
%
%
TA = 125°C, 1000Hrs
0.003
(% of VOUT), 10Hz ≤ f ≤10kHz
3-Lead SOT-223
Thermal Resistance
Junction-to-Case
15.0
10
°C/W
°C/W
°C/W
°C/W
°C/W
3-Lead TO-252
Thermal Resistance
Junction-to-Ambient
No air flow)
3-Lead SOT-223 (No heat sink)
3-Lead TO-252 (No heat sink)(Note 9)
8-Lead LLP(Note 10)
136
92
40
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 TJ(max) , θJA, and TA. The maximum allowable power dissipation at any ambient temperature is
PD = (TJ(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 VIN = VOUT +1.5V.
Note 8: The minimum output current required to maintain regulation.
Note 9: Minimum pad size of 0.038in2
Note 10: Thermal Performance for the LLP was obtained using JESD51-7 board with six vias and an ambient temperature of 22°C. For information about improved
thermal performance and power dissipation for the LLP, refer to Application Note AN-1187.
8
Copyright © 1999-2012, Texas Instruments Incorporated
LM1117/LM1117I
Typical Performance Characteristics
Dropout Voltage (VIN-V OUT
)
Short-Circuit Current
10091923
10091922
Load Regulation
LM1117-ADJ Ripple Rejection
10091943
10091906
LM1117-ADJ Ripple Rejection vs. Current
Temperature Stability
10091925
10091907
Copyright © 1999-2012, Texas Instruments Incorporated
9
LM1117/LM1117I
Adjust Pin Current
LM1117-2.85 Load Transient Response
10091926
10091908
LM1117-5.0 Load Transient Response
LM1117-2.85 Line Transient Response
10091909
10091910
LM1117-5.0 Line Transient Response
10091911
10
Copyright © 1999-2012, Texas Instruments Incorporated
LM1117/LM1117I
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 (CADJ) 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 CADJ should
be less than R1 to prevent the ripple from being amplified:
1/(2π*fRIPPLE*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 fRIPPLE = 120Hz, the CADJ 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 LM1117 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 range between 0.3Ω - 22Ω. In the case of the adjustable regulator, when the CADJ is used,
a larger output capacitance (22µf tantalum) is required.
2.0 OUTPUT VOLTAGE
The LM1117 adjustable version develops a 1.25V reference voltage, VREF, between the output and the adjust terminal. As shown
in Figure 1, this voltage is applied across resistor R1 to generate a constant current I1. The current IADJ from the adjust terminal
could introduce error to the output. But since 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.
10091917
FIGURE 1. Basic Adjustable Regulator
3.0 LOAD REGULATION
The LM1117 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
VLOAD is less than the VOUT by the sum of the voltage drops along the line resistances. In this case, the load regulation seen at the
RLOAD 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.
Copyright © 1999-2012, Texas Instruments Incorporated
11
LM1117/LM1117I
10091918
FIGURE 2. Typical Application using Fixed Output Regulator
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 eliminates line 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 x IL. If R1 (=125Ω) is connected 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.
10091919
FIGURE 3. Best Load Regulation using Adjustable Output Regulator
4.0 PROTECTION DIODES
Under normal operation, the LM1117 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 to ground, 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 VIN. In the LM1117 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.
12
Copyright © 1999-2012, Texas Instruments Incorporated
LM1117/LM1117I
10091915
FIGURE 4. Regulator with Protection Diode
5.0 HEATSINK REQUIREMENTS
When an integrated circuit operates with an 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-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.
θ
θ
R JC (Component
R CA (Application
Variables)
Variables)
Leadframe Size & Material Mounting Pad Size,
Material, & Location
No. of Conduction Pins
Die Size
Placement of Mounting Pad
PCB Size & Material
Traces Length & Width
Adjacent Heat Sources
Die Attach Material
Molding Compound Size
and Material
Volume of Air
Ambient Temperatue
Shape of Mounting Pad
10091937
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
The LM1117 regulators have internal thermal shutdown to protect the device from over-heating. Under all possible operating
conditions, the junction temperature of the LM1117 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, PD , must be calculated:
IIN = IL + IG
PD = (VIN-VOUT)I L + VINIG
Figure 6 shows the voltages and currents which are present in the circuit.
Copyright © 1999-2012, Texas Instruments Incorporated
13
LM1117/LM1117I
10091916
FIGURE 6. Power Dissipation Diagram
The next parameter which must be calculated is the maximum allowable temperature rise, TR(max):
TR(max) = TJ(max)-TA(max)
where TJ(max) is the maximum allowable junction temperature (125°C), and TA(max) is the maximum ambient temperature which
will be encountered in the application.
Using the calculated values for TR(max) and PD, the maximum allowable value for the junction-to-ambient thermal resistance
(θJA) can be calculated:
ꢀθJA = TR(max)/PD
If the maximum allowable value for θJA is found to be ≥136°C/W for SOT-223 package or ≥79°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 θJA falls below these limits, a heatsink is required.
As a design aid, Table 1 shows the value of the θJA of SOT-223 and TO-252 for different heatsink area. The copper patterns that
we used to measure these θJAs 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. Figures Figure 11 and Figure 12 shows the maximum allowable power dissipation vs. copper area (in2) 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.
*Application Note AN-1187 discusses improved thermal performance and power dissipation for the LLP.
TABLE 1. θJA Different Heatsink Area
Layout
Copper Area
Thermal Resistance
Top Side (in2)*
Bottom Side (in2)
(θJA,°C/W) SOT-223
(θJA,°C/W) TO-252
1
2
0.0123
0.066
0.3
0
0
136
123
84
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
75
5
0
69
6
0
66
7
0
0.2
0.4
0.6
0.8
1
115
98
8
0
9
0
89
10
11
12
13
14
15
16
0
82
0
79
0.066
0.175
0.284
0.392
0.5
0.066
0.175
0.284
0.392
0.5
125
93
83
75
70
*Tab of device attached to topside copper
14
Copyright © 1999-2012, Texas Instruments Incorporated
LM1117/LM1117I
10091913
FIGURE 7. θJA vs. 1oz Copper Area for SOT-223
10091934
FIGURE 8. θJA vs. 2oz Copper Area for TO-252
10091912
FIGURE 9. Maximum Allowable Power Dissipation vs. Ambient Temperature for SOT-223
Copyright © 1999-2012, Texas Instruments Incorporated
15
LM1117/LM1117I
10091936
FIGURE 10. Maximum Allowable Power Dissipation vs. Ambient Temperature for TO-252
10091914
FIGURE 11. Maximum Allowable Power Dissipation vs. 1oz Copper Area for SOT-223
10091935
FIGURE 12. Maximum Allowable Power Dissipation vs. 2oz Copper Area for TO-252
16
Copyright © 1999-2012, Texas Instruments Incorporated
LM1117/LM1117I
10091941
FIGURE 13. Top View of the Thermal Test Pattern in Actual Scale
Copyright © 1999-2012, Texas Instruments Incorporated
17
LM1117/LM1117I
10091942
FIGURE 14. Bottom View of the Thermal Test Pattern in Actual Scale
18
Copyright © 1999-2012, Texas Instruments Incorporated
LM1117/LM1117I
Typical Application Circuits
10091930
Adjusting Output of Fixed Regulators
10091931
Regulator with Reference
10091929
1.25V to 10V Adjustable Regulator with Improved Ripple Rejection
10091927
5V Logic Regulator with Electronic Shutdown*
Copyright © 1999-2012, Texas Instruments Incorporated
19
LM1117/LM1117I
10091932
Battery Backed-Up Regulated Supply
10091933
Low Dropout Negative Supply
20
Copyright © 1999-2012, Texas Instruments Incorporated
LM1117/LM1117I
Physical Dimensions inches (millimeters) unless otherwise noted
3-Lead SOT-223
NS Package Number MP04A
3-Lead TO-220
NS Package Number T03B
Copyright © 1999-2012, Texas Instruments Incorporated
21
LM1117/LM1117I
3-Lead TO-263
NS Package Number TS3B
22
Copyright © 1999-2012, Texas Instruments Incorporated
LM1117/LM1117I
3-Lead TO-252
NS Package Number TD03B
8-Lead LLP
NS Package Number LDC08A
Copyright © 1999-2012, Texas Instruments Incorporated
23
Notes
Copyright © 1999-2012, Texas Instruments
Incorporated
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