Advanced Monolithic Systems AMS317 Service Manual

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Advanced AMS317
Monolithic 1A LOW DROPOUT VOLTAGE REGULATOR

Systems
RoHS compliant

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

1V input-to-output differential. The dropout voltage of the device is guaranteed maximum 1.3V at maximum output current,

to
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.

ORDERING INFORMATION:

OUTPUT PACKAGE TYPE OPERATING JUNCTION

VOLTAGE

ADJUSTABLE AMS317ACT AMS317ACM AMS317ACD AMS317A
AMS317CT AMS317CM AMS317CD AMS317
FIXED* AMS317ACT-X AMS317ACM-X AMS317ACD-X AMS317A-X
AMS317CT-X AMS317CM-X AMS317CD-X AMS317-X
X= 1.8V, 2.5V, 2.85V, 3.3V and 5.0V.

*For additional available fixed voltages contact factory.

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

PIN CONNECTIONS

FIXED VERSION

1- Ground
2- V

OUT

3- VIN

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ADJUSTABLE VERSION

1- Adjust
2- V

OUT

3- VIN

TO-220 FRONT VIEW

TAB IS

OUTPUT

3

2

1

•••• Post Regulators for Switching Supplies

TEMPERATURE RANGE

-40 to +125° C
0 to 125° C

-40 to +125° C
0 to 125° C

SOT-223 Top View

TAB IS

OUTPUT

1

2

3

TO-252 FRONT VIEW

3
2
1

TO-263 FRONT VIEW

TAB IS

OUTPUT

2L TO-263 FRONT VIE W

TAB IS

OUTPUT

3

2

1

3

2

1

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AMS317

ABSOLUTE MAXIMUM RATINGS (Note 1)

Power Dissipation Internally limited Thermal Resistance
Input Voltage 25V TO-220 package
Operating Junction Temperature Range TO-263 package
AMS317A
AMS317
Storage temperature
Soldering information
Lead Temperature (25 sec)

-40°C to +125°C
0°C to +125°C

- 65°C to +150°C

265°C

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

can vary from 46°C/W to

JA

ϕ JA= 50°C/W

ϕ JA= 30°C/W

ϕ JA= 80°C/W

ϕ JA= 90°C/W*

Parameter

Reference Voltage
(Note 2)

Output Voltage
(Note 2)

Line Regulation AMS317

Load Regulation

(Notes 2, 3)

Current Limit

Minimum Load
Current

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

Device Conditions AMS317A

Min Typ Max

AMS317 I

AMS317-1.8

AMS317-2.5

AMS317-2.85

AMS317-3.3

AMS317-5.0

AMS317

AMS317/-1.8/-

2.5/-2.85/-3.3/-5.0

AMS317 (VIN - V

= 10 mA

OUT

10mA ≤ I
25V

0 ≤ I

0 ≤ I

0 ≤ I

0 ≤ I

0 ≤ I

I

LOAD

10mA ≤ I

(VIN - V

≤ I

OUT

≤ I

OUT

MAX

≤ I

OUT

MAX

≤ I

OUT

MAX

≤ I

OUT

MAX

≤ I

OUT

MAX

= 10 mA , 3V≤ (VIN - V

≤ I

OUT

) = 5V

OUT

) = 25V

OUT

, 3V≤ (VIN - V

MAX

, 3.3V≤ VIN ≤ 25V

, 4.0V≤ VIN ≤ 25V

, 4.35V≤ VIN ≤ 25V

, 4.75V ≤ VIN ≤ 25V

, 6.5V ≤ VIN ≤ 25V

MAX

OUT

OUT

) ≤ 25V

) ≤

1.238

1.225

1.782

1.764

2.475

2.460

2.793

3.267

3.235

4.950

4.900

1.250

1.250

1.800

1.800

2.500

2.500

2.82

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

5 10

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

0.015

0.1

1.250

1.250

1.800

1.800

2.500

2.500

2.850

2.850

3.300

3.300

5.000

5.000

0.035

0.3

5 10

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

mA

Adjust Pin Current AMS317 40

Adjust Pin Current
Change

Temperature
Stability

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

Ripple Rejection AMS317

RMS Output Noise

(% of V

Thermal Resistance
Junction-to-Case

OUT

)

AMS317

TO-252 Package

10mA ≤ I
25V

T

MIN

f =120Hz , C
(VIN-V

TA = 25°C , 10Hz ≤ f ≤ 10kHz

SOT-223 Package

TO-220 / TO-263 Package

OUT

≤ TJ ≤ T

) = 3V, C

OUT

≤ I

MAX

OUT

, 3V≤ (VIN - V

MAX

= 25µF Tantalum,

=10µF

ADJ

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OUT

) ≤

0.2

1.0

66 80

0.003 0.003 %

5

23.5

5

100

5

5

40

0.2

1.0

66 80

23.5

5

100

5

dB

°C/W

µA
µA

µA

%

°C/W

°C/W

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AMS317

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

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

APPLICATION HINTS

The AMS317 series of adjustable and fixed regulators are easy to

and are protected against short circuit and thermal overloads.

use
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

uminum covers all cases of bypassing the adjustment terminal.

al
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

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out

put 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

AMS317

V

IN

IN OUT

ADJ

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

ADJ

can usually be ignored.

AMS317

V

IN

IN OUT

ADJ

I

ADJ

50µA

V

= V

OUT

REF

Figure 2. Basic Adjustable Regulator

- V

IN

C

ADJ

10µF

(

1+ R2/R1)+I

) ≤ 25V the device is

OUT

+

C

R1

OUT

150µF

V

OUT

R

1

R

2

V

REF

R2

R2

ADJ

V

OUT