Datasheet AMS317CT-5.0, AMS317CT-3.3, AMS317CT-2.85, AMS317CT-2.5, AMS317CT-1.8 Datasheet (ADMOS)

Advanced AMS317
Monolithic 1A LOW DROPOUT VOLTAGE REGULATOR

Systems

FEATURES APPLICATIONS

•• Three Terminal Adjustable or Fixed Voltages* •• High Efficiency Linear Regulators

1.8V, 2.5V, 2.85V, 3.3V and 5.0V

•• 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

••TO-220, TO-263, TO-252 and SOT-223 package available •• Battery Powered Instrumentation

GENERAL DESCRIPTION

The AMS317 series of adjustable and fixed voltage regulators are designed to provide 1A output current and to operate down
to 1V input-to-output differential. The dropout voltage of the device is guaranteed maximum 1.3V at maximum output
current, decreasing at lower load currents.
On-chip trimming adjusts the reference voltage to 1%. Current limit is also trimmed, minimizing the stress under overload
conditions on both the regulator and power source circuitry.
The AMS317 devices are pin compatible with other three-terminal regulators and are offered in 3 lead TO-220 package, in
the 2 & 3 Lead TO-263 (Plastic DD), in the TO-252 (D PAK) and in the low profile surface mount SOT-223 package.

•• Post Regulators for Switching Supplies

ORDERING INFORMATION:

OUTPUT PACKAGE TYPE OPERATING JUNCTION

VOLTAGE

ADJUSTABLE AMS317ACT AMS317ACM AMS317ACD AMS317A

FIXED* AMS317ACT-X AMS317ACM-X AMS317ACD-X AMS317A-X

X= 1.8V, 2.5V, 2.85V, 3.3V and 5.0V.
*For additional available fixed voltages contact factory.

PIN CONNECTIONS

FIXED VERSION ADJUSTABLE VERSION

1- Ground
2- V

OUT

3- V

IN

3 Lead TO-220 2 &3 Lead TO-263 TO-252 SOT-223

AMS317CT AMS317CM AMS317CD AMS317

AMS317CT-X AMS317CM-X AMS317CD-X AMS317-X

SOT-223 Top View

1- Adjust
2- V

OUT

3- V

IN

TAB IS

OUTPUT

TO-220 FRONT VIEW

3
2

1

TAB IS

OUTPUT

1

2 3

TO-252 FRONT VIEW

3
2
1

TEMPERATURE RANGE

-40 to +125° C
0 to 125° C

-40 to +125° C
0 to 125° C

TO-263 FRONT VIEW

TAB IS

OUTPUT

2L TO-263 FRONT VIEW

TAB IS

OUTPUT

3
2
1

3
2
1

Advanced Monolithic Systems, Inc. 6680B Sierra Lane, Dublin, CA 94568 Phone [phone] Fax [phone]

ABSOLUTE MAXIMUM RATINGS (Note 1)

Junction Temperature Range

JA

Power Dissipation Internally limited Thermal Resistance
Input Voltage 25V TO-220 package
Operating
AMS317A
AMS317
Storage temperature
Soldering information
Lead Temperature (10 sec)

-40°C to +125°C
0°C to +125°C

- 65°C to +150°C

300°C

TO-263 package
TO-252 package
SOT-223 package

* With package soldering to copper area over backside ground
plane or internal power plane ϕ
>90°C/W (for SOT-223) (20°C/W to >40°C/W for TO-263)
depending on mounting technique and the size of the copper
area.

ELECTRICAL CHARACTERISTICS

Electrical Characteristics at I

= 10 mA, (VIN - V

OUT

) = 5V, and TJ = +25°C unless otherwise specified.

OUT

AMS317

ϕ JA= 50°C/W

ϕ JA= 30°C/W

ϕ JA= 80°C/W

ϕ JA= 90°C/W*

can vary from 46°C/W to

Parameter Device Conditions AMS317A

Min Typ Max

Reference Voltage
(Note 2)

Output Voltage
(Note 2)

Line Regulation AMS317

Load Regulation
(Notes 2, 3)

Current Limit AMS317/-1.8/-

AMS317 I

AMS317-1.8

AMS317-2.5

AMS317-2.85

AMS317-3.3

AMS317-5.0

AMS317

= 10 mA

OUT

10mA ≤ I

0 ≤ I

0 ≤ I

0 ≤ I

0 ≤ I

0 ≤ I
I

LOAD

10mA ≤ I

(VIN - V

≤ I

OUT

≤ I

OUT

OUT

OUT

OUT

OUT

, 3.3V≤ VIN ≤ 25V

MAX

≤ I

, 4.0V≤ VIN ≤ 25V

MAX

≤ I

, 4.35V≤ VIN ≤ 25V

MAX

≤ I

, 4.75V ≤ VIN ≤ 25V

MAX

≤ I

, 6.5V ≤ VIN ≤ 25V

MAX

= 10 mA , 3V≤ (VIN - V

≤ I

OUT

) = 5V

OUT

, 3V≤ (VIN - V

MAX

MAX

OUT

) ≤ 25V

OUT

) ≤ 25V

1.238

1.225

1.782

1.764

2.475

2.460

2.82

2.793

3.267

3.235

4.950

4.900

1.250

1.250

1.800

1.800

2.500

2.500

2.850

2.850

3.300

3.300

5.000

5.000

0.015

0.035

0.1

0.3

1.5 2.0 1.5 2.0

1.262

1.270

1.818

1.836

2.525

2.560

2.88

2.907

3.333

3.365

5.050

5.100

0.2

0.2

0.5

1.0

AMS317

Min Typ Max

1.225

1.764

1.746

2.450

2.425

2.793

2.765

3.235

3.201

4.900

4.850

1.20

1.250

1.250

1.800

1.800

2.500

2.500

2.850

2.850

3.300

3.300

5.000

5.000

0.015

0.035

0.1

0.3

1.270

1.30

1.836

1.854

2.550

2.575

2.907

2.935

3.365

3.399

5.100

5.150

0.2

0.2

0.5

1.0

Units

V
V

V
V

V
V

V
V

V
V

V
V

%
%

%
%

A

2.5/-2.85/-3.3/-5.0

Minimum Load

AMS317 (VIN - V

OUT

) = 25V

5 10 5 10

mA

Current
Thermal Regulation AMS317 TA = 25°C, 20ms pulse 0.04 0.07 0.04 0.07 %W

Adjust Pin Current AMS317 40

Adjust Pin Current
Change

Temperature
Stability

AMS317

10mA ≤ I

T

≤ TJ ≤ T

MIN

OUT

≤ I

MAX

MAX

, 3V≤ (VIN - V

OUT

) ≤ 25V

0.2 5 0.2 5

1.0 1.0

100

40

100

µA
µA

µA

Long Term Stability TA =125°C, 1000Hrs 0.3 1 0.3 1 %
Ripple Rejection AMS317

RMS Output Noise
(% of V

OUT

)

Thermal Resistance
Junction-to-Case

f =120Hz , C
(VIN-V

OUT

= 25µF Tantalum,

OUT

) = 3V, C

ADJ

=10µF

TA = 25°C , 10Hz ≤ f ≤ 10kHz

TO-252 Package
SOT-223 Package
TO-220 / TO-263 Package

66 80 66 80

0.003 0.003 %

5

23.5
5

5

23.5
5

°C/W
°C/W
°C/W

Advanced Monolithic Systems, Inc. 6680B Sierra Lane, Dublin, CA 94568 Phone [phone] Fax [phone]

%

dB

AMS317

ADJ

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. Parameters identified with boldface type apply over the full
operating temperature range.

Note 2: Line and Load regulation are guaranteed up to the maximum power dissipation of 1.2 W. 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: Minimum load current is defined as the minimum output current required to maintain regulation. When 3V ≤ (V

to regulate if the output current is greater than 10mA.

APPLICATION HINTS

- V

) ≤ 25V the device is guaranteed

IN

OUT

The AMS317 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 AMS317 series requires the use of
an output capacitor as part of the device frequency compensation.
The addition of 150µF aluminum electrolytic or a 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 or 150µF
aluminum covers all cases of bypassing the adjustment terminal.
Without bypassing the adjustment terminal smaller capacitors can
be used with equally good results.
To ensure good transient response with heavy load current
changes capacitor values on the order of 100µF are used in the
output of many regulators. To further improve stability and
transient response of these devices larger values of output
capacitor can be used.

Protection Diodes

Unlike older regulators, the AMS317 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
AMS317 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 AMS317 is used (Figure 1).

D1

V

IN

IN OUT

ADJ

C

10µF

ADJ

+

R

1

R

2

AMS317

C

150µF

OUT

V

OUT

Figure 1.

Output Voltage

The AMS317 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

is very small and constant it represents a small

error and it can usually be ignored.

V

IN

V

OUT

IN OUT

ADJ

I

ADJ

50µA

= V

(1+ R2/R1)+I

REF

V

REF

ADJ

AMS317

R2

R1

R2

V

OUT

Figure 2. Basic Adjustable Regulator

Advanced Monolithic Systems, Inc. 6680B Sierra Lane, Dublin, CA 94568 Phone [phone] Fax [phone]

APPLICATION HINTS

AMS317

Load Regulation

True remote load sensing it is not possible to provide, because the
AMS317 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

R1

Connected as shown , R

x ( R2+R1 ) , R

P

V

IN

P

AMS317

IN OUT

ADJ

= Parasitic Line Resistance

P

is not multiplied by the divider ratio

R

P

PARASITIC

LINE RESISTANCE

R1*

R2*

R

L

The thermal resistance from the junction to the tab for the
AMS317 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 the TO-252 package, if the maximum allowable value is
found to be ≥92°C/W, no heat sink is needed since the package
alone will dissipate enough heat to satisfy these requirements. If
the calculated value for θJA falls bellow these limits, a heat sink
is required.
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 AMS317 is equal to:

PD = ( VIN - V

OUT

)( I

OUT

)
Maximum junction temperature will be equal to:
TJ = T

+ PD(Thermal Resistance (junction-to-ambient))

A(MAX)

Maximum junction temperature must not exceed 125°C.

Ripple Rejection

*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 AMS317 series have internal power and thermal limiting
circuitry designed to protect the device under overload conditions.

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

).

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.

Advanced Monolithic Systems, Inc. 6680B Sierra Lane, Dublin, CA 94568 Phone [phone] Fax [phone]

Table 1.

COPPER AREA THERMAL RESISTANCE

TOP SIDE* BACK SIDE BOARD AREA (JUNCTION-TO-AMBIENT)

2500 Sq. mm 2500 Sq. mm 2500 Sq. mm
1000 Sq. mm 2500 Sq. mm 2500 Sq. mm

225 Sq. mm 2500 Sq. mm 2500 Sq. mm

100 Sq. mm 2500 Sq. mm 2500 Sq. mm
1000 Sq. mm 1000 Sq. mm 1000 Sq. mm
1000 Sq. mm 0 1000 Sq. mm

45°C/W
45°C/W
53°C/W
59°C/W
52°C/W
55°C/W

* Tab of device attached to topside copper.

TYPICAL PERFORMANCE CHARACTERISTICS

AMS317

Minimum Operating Current
(Adjustable Device)

12

9

6

3

MINIMUM OPERATING CURRENT (mA)

0

0 5 10 15 20

INPUT/OUTPUT DIFFERENTIAL (V)

TJ =

125°C

TJ = 25°C

Short-Circuit Current

1.25

1.00

0.75

0.50

SHORT CIRCUIT CURRENT (A)

0.25

0

0 5 10 15

INPUT/OUTPUT DIFFERENTIAL

Load Regulation Ripple Rejection vs. Current

0.10
∆ I

= 1A

LOAD

0.05

0

-0.05

-0.10

OUTPUT VOLTAGE DEVIATION (%)

-0.15

-0.20

-50 -25 0 25 50 75 100 125
TEMPERATURE (°C)

100

90

80

70

60

50

40

30

RIPPLE REJECTION (dB)

20

10

0

0 0.2 0.4 0.6 0.8

V

= 5V

OUT

C

= 25µF

ADJ

C

= 25µF

OUT

V

RIPPLE

OUTPUT CURRENT (A)

V

≤

3Vp-p

RIPPLE

TJ = 125°C

TJ = 25°C

f

f

≤

0.5Vp-p

RIPPLE

RIPPLE

= 120Hz

= 20Hz

Advanced Monolithic Systems, Inc. 6680B Sierra Lane, Dublin, CA 94568 Phone [phone] Fax [phone]

TYPICAL PERFORMANCE CHARACTERISTICS (Continued).

AMS317

Temperature Stability

2.0

1.0

0

-1.0

OUTPUT VOLTAGE CHANGE (%)

-2.0

-50 -25 0 25 50 75 100 125 150
TEMPERATURE (°C)

100

90

80

A)

µ

70

60

50

40

30

ADJUST PIN CURRENT (

20

10

0

-50 -25 0 25 50 75 100 125 150

PACKAGE DIMENSIONS inches (millimeters) unless otherwise noted.

Adjust Pin Current

TEMPERATURE (°C)

(11.684-12.700)

0.980-1.070

(24.892-27.178)

0.460-0.500

0.520-0.570

(13.208-14.478)

0.090-0.110

(2.286-2.794)

3 LEAD TO-220 PLASTIC PACKAGE (T)

0.390-0.415

(9.906-10.541)

0.028-0.038

(0.711-0.965)

0.147-0.155

(3.734-3.937)

0.230-0.270

(5.842-6.858)

0.330-0.370

(8.382-9.398)

0.050

(1.270)

TYP

DIA

0.570-0.620

(14.478-15.748)

0.218-0.252

(5.537-6.401)

0.165-0.180

(4.191-4.572)

0.013-0.023

(0.330-0.584)

0.045-0.055

(1.143-1.397)

0.095-0.115

(2.413-2.921)

T (TO-220) AMS DRW# 042193

Advanced Monolithic Systems, Inc. 6680B Sierra Lane, Dublin, CA 94568 Phone [phone] Fax [phone]

PACKAGE DIMENSIONS inches (millimeters) unless otherwise noted (Continued).

3 LEAD TO-263 PLASTIC DD (M)

AMS317

0.090-0.110

(2.286-2.794)

0.060

0.390-0.415

(9.906-10.541)

(1.524)

0.330-0.370

(8.382-9.398)

0.032
(0.81)

TYP

TYP

0.199-0.218
(5.05-5.54 )

2 LEAD TO-263 PLASTIC DD (M)

0.060

0.390-0.415

(9.906-10.541)

(1.524)

TYP

0.165-0.180

(4.191-4.572)

0.165-0.180

(4.191-4.572)

0.108

(2.74)

TYP

0.013-0.023

(0.330-0.584)

0.045-0.055

(1.143-1.397)

+0.008

0.004

-0.004

+0.203

(

0.102

-0.102

0.095-0.115

(2.413-2.921)

0.90-0.110

(2.29-2.79)

M (DD3) AMS DRW# 042191R1

0.045-0.055

(1.143-1.397)

)

+0.008

0.004

-0.004

+0.203

(

0.102

-0.102

0.095-0.115

(2.413-2.921)

0.90-0.110

(2.29-2.79)

M (DD2) AMS DRW# 072191

)

0.0295

(0.7495)

TYP

0.090-0.110

(2.286-2.794)

0.330-0.370

(8.382-9.398)

0.032
(0.81)

TYP

0.199-0.218
(5.05-5.54 )

0.108

(2.74)

TYP

0.013-0.023

(0.330-0.584)

Advanced Monolithic Systems, Inc. 6680B Sierra Lane, Dublin, CA 94568 Phone [phone] Fax [phone]

PACKAGE DIMENSIONS inches (millimeters) unless otherwise noted (Continued).

TO-252 PLASTIC PACKAGE (D)

0.258-0.262

0.023-0.027

(0.584-0.685)

0.020-0.030

(0.508-0.762)

0.175-0.180

(4.191-4.445)

(6.553-6.654)

0.208-0.212

(5.283-5.384)

0.020-0.030

(0.508-0.762)

0.033-0.037

(0.838-0.939)

45.0°

0.057-0.067

(0.144-0.170)

DIA

0.085-0.095

(2.159-2.413)

7.0°

0.030-0.034

(0.762-0.863)

0.038-0.042
(0.965-1.066)

0.235-0.245
(5.969-6.223)

AMS317

0.264-0.287
(6.71-7.29)

0.025

(0.635)

TYP

0.130-0.146
(3.30-3.71)

0.088-0.092

(2.235-2.336)

0.038

0.099-0.103

(2.514-2.615)

0.030

(0.762)

TYP

(0.965)

TYP

0.018-0.022

(0.451-0.558)

3 LEAD SOT-223 PLASTIC PACKAGE

0.248-0.264

(6.30-6.71)

0.116-0.124
(2.95-3.15)

0.038-0.042
(0.965-1.066)

0.024±0.002

(0.610±0.0508)

D (D3) AMS DRW# 042891

0.033-0.041
(0.84-1.04)

0.012
(0.31)

MIN

10°

MAX

10°-16°

0.025-0.033
(0.64-0.84)

0.010-0.014
(0.25-0.36)

10°-16°

(SOT-223 ) AMS DRW# 042292

0.071
(1.80)

MAX

0.090
(2.29)

NOM

0.025-0.033
(0.64-0.84)

0.181
(4.60)

NOM

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