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Advanced
AMS1117
Monolithic
1A LOW DROPOUT VOLTAGE REGULATOR
Systems
RoHs Compliant
FEATURES
APPLICATIONS
•
••
• Three Terminal Adjustable or Fixed Voltages* •
••
• High Efficiency Linear Regulators
1.5V, 1.8V, 2.5V, 2.85V, 3.3V and 5.0V •
••
•
Post Regulators for Switching Supplies
•
••
• Output Current of 1A •
••
• 5V to 3.3V Linear Regulator
•
••
• Operates Down to 1V Dropout •
••
• Battery Chargers
•
••
• Line Regulation: 0.2% Max. •
••
• Active SCSI Terminators
•
••
• Load Regulation: 0.4% Max. •
••
• Power Management for Notebook
•
••
• SOT-223, TO-252 and SO-8 package available •
••
• Battery Powered Instrumentation
GENERAL DESCRIPTION
The
The AMS1117 series of adjustable and fixed voltage regulators are designed to provide up to1A output current and to operate
down to 1V input-to-output differential. The dropout voltage of the device is guaranteed maximum 1.3V, decreasing at lower
load currents.
On-chip trimming adjusts the reference voltage to 1.5%. Current limit is set to minimize the stress under overload conditions
on both the regulator and power source circuitry.
The AMS1117 devices are pin compatible with other three-terminal SCSI regulators and are offered in the low profile surface
mount SOT-223 package, in the 8L SOIC package and in the TO-252 (DPAK) plastic package.
ORDERING INFORMATION:
PACKAGE TYPE OPERATING JUNCTION
TO-252 SOT-223 8L SOIC TEMPERATURE RANGE
AMS1117CD AMS1117 AMS1117CS -40 to 125° C
AMS1117CD-1.5 AMS1117-1.5 AMS1117CS-1.5 -40 to 125° C
AMS1117CD-1.8 AMS1117-1.8 AMS1117CS-1.8 -40 to 125° C
AMS1117CD-2.5 AMS1117-2.5 AMS1117CS-2.5 -40 to 125° C
AMS1117CD-2.85
AMS1117-2.85 AMS1117CS-2.85 -40 to 125° C
AMS1117CD-3.3 AMS1117-3.3 AMS1117CS-3.3 -40 to 125° C
AMS1117CD-5.0 AMS1117-5.0 AMS1117CS-5.0 -40 to 125° C
*For additional available fixed voltages contact factory.
PIN CONNECTIONS
3 PIN FIXED/ADJUSTABLE
VERSION
1- Ground/Adjust
2- V
OUT
3- V
IN
SOT-223 Top View
123
8L SOIC Top View
1
2
8
4
3
7
5
6
V
OUT
N/C
V
OUT
GND/ADJ
V
OUT
V
OUT
N/C
V
IN
TAB IS
OUTPUT
TO-252 FRONT VIEW
1
2
3
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AMS1117
ABSOLUTE MAXIMUM RATINGS
(Note 1)
Power Dissipation Internally limited Soldering information
Input Voltage 15V Lead Temperature (25 sec) 265°C
Operating
Thermal Resistance
Control Section -40°C to 125°C SO-8 package ϕ
JA
= 160°C/W
Power Transistor -40°C to 125°C TO-252 package ϕ
JA
= 80°C/W
Storage temperature - 65°C to +150°C SOT-223 package ϕ
JA
= 90°C/W*
* With package soldering to copper area over backside
ground plane or internal power plane ϕ
JA
can vary from
46°C/W to >90°C/W depending on mounting technique and
the size of the copper area.
ELECTRICAL CHARACTERISTICS
Electrical Characteristics at I
OUT
= 0 mA, and T
J
= +25°C unless otherwise specified.
Parameter
Device Conditions Min Typ Max Units
Reference Voltage
(Note 2)
AMS1117 I
OUT
= 10 mA
1.5V≤ (V
IN
- V
OUT
) ≤ 12V
1.232
1.2125
1.250
1.250
1.268
1.2875
V
V
Output Voltage
(Note 2)
AMS1117-1.5 V
IN
= 3V 1.478
1.455
1.500
1.500
1.522
1.545
V
V
AMS1117-1.8 V
IN
= 3.3V 1.773
1.746
1.800
1.800
1.827
1.854
V
V
AMS1117-2.5 V
IN
= 4V 2.463
2.425
2.500
2.500
2.537
2.575
V
V
AMS1117-2.85 V
IN
= 4.35V 2.808
2.7645
2.850
2.850
2.892
2.9355
V
V
AMS1117-3.3 V
IN
= 4.8V 3.251
3.201
3.300
3.300
3.349
3.399
V
V
AMS1117-5.0 V
IN
= 6.5V 4.925
4.850
5.000
5.000
5.075
5.150
V
V
Line Regulation AMS1117 1.5V≤ (V
IN
- V
OUT
) ≤ 12V 0.015
0.035
0.2
0.2
%
%
AMS1117-1.5 1.5V≤ (V
IN
- V
OUT
) ≤ 12V 0.3
0.6
5
6
mV
mV
AMS1117-1.8 1.5V≤ (V
IN
- V
OUT
) ≤ 12V 0.3
0.6
5
6
mV
mV
AMS1117-2.5 1.5V≤ (V
IN
- V
OUT
) ≤ 12V 0.3
0.6
6
6
mV
mV
AMS1117-2.85 1.5V≤ (V
IN
- V
OUT
) ≤ 12V 0.3
0.6
6
6
mV
mV
AMS1117-3.3 1.5V≤ (V
IN
- V
OUT
) ≤ 12V 0.5
1.0
10
10
mV
mV
AMS1117-5.0 1.5V≤ (V
IN
- V
OUT
) ≤ 12V 0.5
1.0
10
10
mV
mV
Load Regulation
(Notes 2, 3)
AMS1117 (V
IN
- V
OUT
) =1.5V, 10mA ≤ I
OUT
≤ 0.8A 0.1
0.2
0.3
0.4
%
%
AMS1117-1.5 V
IN
= 3V, 0 ≤ I
OUT
≤ 0.8A 3
6
10
20
mV
mV
AMS1117-1.8 V
IN
= 3.3V, 0 ≤ I
OUT
≤ 0.8A 3
6
10
20
mV
mV
AMS1117-2.5 V
IN
= 5V, 0 ≤ I
OUT
≤ 0.8A 3
6
12
20
mV
mV
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AMS1117
ELECTRICAL CHARACTERISTICS
Electrical Characteristics at I
OUT
= 0 mA, and T
J
= +25°C unless otherwise specified.
Parameter
Device Conditions Min Typ Max Units
Load Regulation
(Notes 2, 3)
AMS1117-2.85 V
IN
= 4.35V, 0 ≤ I
OUT
≤ 0.8A 3
6
12
20
mV
mV
AMS1117-3.3 V
IN
= 4.75V, 0 ≤ I
OUT
≤ 0.8A 3
7
15
25
mV
mV
AMS1117-5.0 V
IN
= 6.5V, 0 ≤ I
OUT
≤ 0.8A 5
10
20
35
mV
mV
Dropout Voltage
(V
IN
- V
OUT
)
AMS1117-1.5/-1.8/-2.5/-
2.85/-3.3/-5.0
∆V
OUT
, ∆V
REF
= 1%, I
OUT
= 0.8A (Note 4)
1.1 1.3
V
Current Limit
AMS1117-1.5/-1.8/-2.5/-
2.85/-3.3/-5.0
(V
IN
- V
OUT
) = 1.5V
900 1,100 1,500 mA
Minimum Load
Current
AMS1117 (V
IN
- V
OUT
) = 1.5V (Note 5) 5 10 mA
Quiescent Current AMS1117-1.5/-1.8/-2.5/-
2.85/-3.3/-5.0
(V
IN
- V
OUT
) = 1.5V
5
11
mA
Ripple Rejection AMS1117 f =120Hz , C
OUT
= 22µF Tantalum, I
OUT
= 1A,
(V
IN
-V
OUT
) = 3V, C
ADJ
=10µF
60 75 dB
AMS1117-1.5/-1.8/-2.5/-
2.85
f =120Hz , C
OUT
= 22µF Tantalum, I
OUT
= 1A,
V
IN
= 4.35V
60
72
dB
AMS1117-3.3 f =120Hz , C
OUT
= 22µF Tantalum, I
OUT
= 1A
V
IN
= 4.75V
60 72
dB
AMS1117-5.0 f =120Hz , C
OUT
= 22µF Tantalum, I
OUT
= 1A
V
IN
= 6.5V
60 68
dB
Thermal Regulation AMS1117 T
A
= 25°C, 30ms pulse 0.008 0.04 %W
Adjust Pin Current AMS1117 I
OUT
=10mA , 1.5V≤ (V
IN
- V
OUT
) ≤ 12V 55
120
µA
µA
Adjust Pin Current
Change
AMS1117 I
OUT
=10mA, 1.5V≤ (V
IN
- V
OUT
) ≤ 12V 0.2
5
µA
Temperature Stability 0.5 %
Long Term Stability T
A
=125°C, 1000Hrs 0.3 1 %
RMS Output Noise
(% of V
OUT
)
T
A
= 25°C , 10Hz ≤ f ≤ 10kHz 0.003
%
Thermal Resistance
Junction-to-Case
All packages
15 °C/W
Parameters identified with boldface type apply over the full operating temperature range.
Note 1:
Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. For guaranteed specifications and test conditions, see the
Electrical Characteristics. The guaranteed specifications apply only for the test conditions listed.
Note 2:
Line and Load regulation are guaranteed up to the maximum power dissipation of 1.2 W for SOT-223, 2.2W for TO-252 and 780mW for 8-Lead
SOIC. Power dissipation is determined by the input/output differential and the output current. Guaranteed maximum power dissipation will not be available
over the full input/output range.
Note 3:
See thermal regulation specifications for changes in output voltage due to heating effects. Line and load regulation are measured at a constant
junction temperature by low duty cycle pulse testing. Load regulation is measured at the output lead ~1/8” from the package.
Note 4:
Dropout voltage is specified up to 0.8A load. For currents over 0.8A dropout will be higher
Note 5:
Minimum load current is defined as the minimum output current required
to maintain regulation. When 1.5V ≤ (V
IN
- V
OUT
) ≤ 12V the device is
guaranteed to regulate if the output current is greater than 10mA.
Advanced Monolithic Systems, Inc. www.advanced-monolithic.com Phone (925) 443-0722 Fax (925) 443-0723
AMS1117
APPLICATION HINTS
The AMS1117 series of adjustable and fixed regulators are easy to
use and are protected against short circuit and thermal overloads.
Thermal protection circuitry will shut-down the regulator should
the junction temperature exceed 165°C at the sense point.
Pin compatible with older three terminal adjustable regulators,
these devices offer the advantage of a lower dropout voltage, more
precise reference tolerance and improved reference stability with
temperature.
Stability
The circuit design used in the AMS1117 series requires the use of
an output capacitor as part of the device frequency compensation.
The addition of
22µF solid tantalum on the output will ensure
stability for all operating conditions.
When the adjustment terminal is bypassed with a capacitor to
improve the ripple rejection, the requirement for an output
capacitor increases. The value of 22µF tantalum covers all cases of
bypassing the adjustment terminal. Without bypassing the
adjustment terminal smaller capacitors can be used with equally
good results.
To further improve stability and transient response of these
devices larger values of output capacitor can be used.
Protection Diodes
Unlike older regulators, the AMS1117 family does not need any
protection diodes between the adjustment pin and the output and
from the output to the input to prevent over-stressing the die.
Internal resistors are limiting the internal current paths on the
AMS1117 adjustment pin, therefore even with capacitors on the
adjustment pin no protection diode is needed to ensure device
safety under short-circuit conditions.
Diodes between the input and output are not usually needed.
Microsecond surge currents of 50A to 100A can be handled by the
internal diode between the input and output pins of the device. In
normal operations it is difficult to get those values of surge
currents even with the use of large output capacitances. If high
value output capacitors are used, such as 1000µF to 5000µF and
the input pin is instantaneously shorted to ground, damage can
occur. A diode from output to input is recommended, when a
crowbar circuit at the input of the AMS1117 is used (Figure 1).
AMS1117
IN OUT
ADJ
+
C
OUT
2
2µ
F
V
OUT
R
1
R
2
C
ADJ
10
µ
F
D1
V
IN
Ĥigure 1.
Output Voltage
The AMS1117 series develops a 1.25V reference voltage between
the output and the adjust terminal. Placing a resistor between these
two terminals causes a constant current to flow through R1 and
down through R2 to set the overall output voltage. This current is
normally the specified minimum load current of 10mA. Because
I
ADJ
is very small and constant it represents a small error and it
can usually be ignored.
AMS1117
IN OUT
ADJ R1
R2
V
OUT
V
REF
V
IN
I
ADJ
50
µ
A
V
OUT
= V
REF
(1+ R2/R1)+I
ADJ
R2
Figure 2. Basic Adjustable Regulator
Load Regulation
True remote load sensing it is not possible to provide, because the
AMS1117 is a three terminal device. The resistance of the wire
connecting the regulator to the load will limit the load regulation.
The data sheet specification for load regulation is measured at the
bottom of the package. Negative side sensing is a true Kelvin
connection, with the bottom of the output divider returned to the
negative side of the load.
The best load regulation is obtained when the top of the resistor
divider R1 is connected directly to the case not to the load. If R1
were connected to the load, the effective resistance between the
regulator and the load would be:
R
P
x
( R2+R1 ) , R
P
= Parasitic Line Resistance
R1
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AMS1117
APPLICATION HINTS
Connected as shown , R
P
is not multiplied by the divider ratio
AMS1117
IN OUT
ADJ
R
L
R1*
R2*
V
IN
R
P
PARASITIC
LINE RESISTANCE
*
CONNECT R1 TO CASE
CONNECT R2 TO LOAD
Figure 3. Connections for Best Load Regulation
In the case of fixed voltage devices the top of R1 is connected
Kelvin internally, and the ground pin can be used for negative side
sensing.
Thermal Considerations
The AMS1117 series have internal power and thermal limiting
circuitry designed to protect the device under overload conditions.
However maximum junction temperature ratings of 125
°C
should
not be exceeded under continuous normal load conditions.
Careful consideration must be given to all sources of thermal
resistance from junction to ambient. For the surface mount
package SOT-223 additional heat sources mounted near the device
must be considered. The heat dissipation capability of the PC
board and its copper traces is used as a heat sink for the device.
The thermal resistance from the junction to the tab for the
AMS1117 is 15
°C/W.
Thermal resistance from tab to ambient can
be as low as 30°C/W.
The total thermal resistance from junction to ambient can be as
low as 45°C/W. This requires a reasonable sized PC board with at
least on layer of copper to spread the heat across the board and
couple it into the surrounding air.
Experiments have shown that the heat spreading copper layer does
not need to be electrically connected to the tab of the device. The
PC material can be very effective at transmitting heat between the
pad area, attached to the pad of the device, and a ground plane
layer either inside or on the opposite side of the board. Although
the actual thermal resistance of the PC material is high, the
Length/Area ratio of the thermal resistance between layers is
small. The data in Table 1, was taken using 1/16” FR-4 board with
1 oz. copper foil, and it can be used as a rough guideline for
estimating thermal resistance.
For each application the thermal resistance will be affected by
thermal interactions with other components on the board. To
determine the actual value some experimentation will be
necessary.
The power dissipation of the AMS1117 is equal to:
P
D
= ( V
IN
- V
OUT
)( I
OUT
)
Maximum junction temperature will be equal to:
T
J
= T
A(MAX)
+ P
D
(Thermal Resistance (junction-to-ambient))
Maximum junction temperature must not exceed 125°C.
Ripple Rejection
The ripple rejection values are measured with the adjustment pin
bypassed. The impedance of the adjust pin capacitor at the ripple
frequency should be less than the value of R1 (normally 100Ω to
200Ω) for a proper bypassing and ripple rejection approaching the
values shown. The size of the required adjust pin capacitor is a
function of the input ripple frequency. If R1=100Ω at 120Hz the
adjust pin capacitor should be >13µF. At 10kHz only 0.16µF is
needed.
The ripple rejection will be a function of output voltage, in circuits
without an adjust pin bypass capacitor. The output ripple will
increase directly as a ratio of the output voltage to the reference
voltage (V
OUT
/ V
REF
).
Table 1.
COPPER AREA THERMAL RESISTANCE
TOP SIDE* BACK SIDE BOARD AREA (JUNCTION-TO-AMBIENT)
2500 Sq. mm 2500 Sq. mm 2500 Sq. mm
55°C/W
1000 Sq. mm 2500 Sq. mm 2500 Sq. mm
55°C/W
225 Sq. mm 2500 Sq. mm 2500 Sq. mm
65°C/W
100 Sq. mm 2500 Sq. mm 2500 Sq. mm
80°C/W
1000 Sq. mm 1000 Sq. mm 1000 Sq. mm
60°C/W
1000 Sq. mm 0 1000 Sq. mm
65°C/W
* Tab of device attached to topside copper.
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AMS1117
TYPICAL PERFORMANCE CHARACTERISTICS
Minimum Operating Current
(Adjustable Device) Short-Circuit Current
Load Regulation Ripple Rejection vs. Current
Adjust Pin CurrentTemperature Stability
0 5 10 15 20
0
3
6
9
12
INPUT/OUTPUT DIFFERENTIAL (V)
0 5 10 15
MINIMUM OPERATING CURRENT (mA)
INPUT/OUTPUT DIFFERENTIAL
0
0.25
0.50
0.75
1.00
1.25
SHORT CIRCUIT CURRENT (A)
-50 -25 0 25 50 75 100 125
-0.20
-0.15
-0.10
-0.05
0
0.05
0.10
TEMPERATURE (°C)
OUTPUT VOLTAGE DEVIATION (%)
0 0.25 0.5 0.75 1.0
0
10
20
30
40
50
60
70
80
90
100
OUTPUT CURRENT (A)
RIPPLE REJECTION (dB)
-50 -25 0 25 50 75 100 125 150
-2.0
-1.0
0
1.0
2.0
TEMPERATURE (°C)
OUTPUT VOLTAGE CHANGE (%)
TEMPERATURE (°C)
-50 -25 0 25 50 75 100 125 150
0
10
20
30
40
50
60
70
80
90
100
ADJUST PIN CURRENT (
µ
A)
T
J
= 125°C
T
J
= 25°C
f
RIPPLE
= 120Hz
f
RIPPLE
= 20Hz
V
RIPPLE
≤
3Vp-p
V
RIPPLE
≤
0.5Vp-p
∆
I
LOAD
= 1A
V
OUT
= 5V
C
ADJ
= 25
µ
F
C
OUT
= 25
µ
F
T
J
= 125°C
T
J
= 25°C
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AMS1117
PACKAGE DIMENSIONS
inches (millimeters) unless otherwise noted.
TO-252 PLASTIC PACKAGE (D)
0.030
(0.762)
TYP
0.087-0.094
(2.21-2.39) 0.018-0.023
(0.46-0.58)
0.020±0.002
(0.510±0.0508)
0.018-0.023
(0.46-0.58)
D (D3) AMS DRW# 011601
0.035-0.050
(0.89-1.27)
0.035-0.045
(0.89-1.14)
0.235-0.245
(5.969-6.223)
0.156-0.204
(3.96-5.18)
0.255-0.265
(6.48-6.73)
0.206-0.214
(5.23-5.44)
0.025
(0.635)
TYP
7.0°
0.380-0.410
(9.65-10.41)
0.045-0.060
(1.14-1.52)
3 LEAD SOT-223 PLASTIC PACKAGE
0.130-0.146
(3.30-3.71)
0.248-0.264
(6.30-6.71)
0.116-0.124
(2.95-3.15)
0.264-0.287
(6.71-7.29)
0.090
(2.29)
NOM
0.071
(1.80)
MAX
0.033-0.041
(0.84-1.04)
0.025-0.033
(0.64-0.84)
0.181
(4.60)
NOM
0.012
(0.31)
MIN
0.025-0.033
(0.64-0.84)
10°
MAX
10°-16°
10°-16°
0.010-0.014
(0.25-0.36)
(SOT-223 ) AMS DRW# 042292
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AMS1117
PACKAGE DIMENSIONS
inches (millimeters) unless otherwise noted (Continued).
8 LEAD SOIC PLASTIC PACKAGE (S)
0°-8° TYP
0.010-0.020
(0.254-0.508)
S (SO-8 ) AMS DRW# 042293
x 45°
0.016-0.050
(0.406-1.270)
0.008-0.010
(0.203-0.254)
0.004-0.010
(0.101-0.254)
0.014-0.019
(0.355-0.483)
0.053-0.069
(1.346-1.752)
0.050
(1.270)
TYP
0.150-0.157**
(3.810-3.988)
0.228-0.244
(5.791-6.197)
0.189-0.197*
(4.801-5.004)
*DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH
SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
**DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD
FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE
1 2 3 4
8 7 6 5