Advanced Monolithic Systems AMS1508 Service Manual

http://www.BDTIC.com/AMS

Advanced AMS1508
Monolithic 8A LOW DROPOUT VOLTAGE REGULATORS

Systems
RoHS compliant

FEATURES APPLICATIONS

•••• Adjustable or Fixed Output •••• High Current Regulators

1.5V, 2.5V, 2.85V, 3.0V, 3.3V, 3.5V and 5.0V

• Output Current of 10A •••• Microprocessor Supply

•

•

•

•••• Low Dropout, 500mV at 10A Output Current •••• Adjustable Power Supply

•••• Fast Transient Response •••• Notebook/Personal Computer Supplies

•••• Remote Sense

GENERAL DESCRIPTION

The AMS1508 series of adjustable and fixed low dropout voltage regulators are designed to provide 8A output current to

ower the new generation of microprocessors. The dropout voltage of the device is 100mV at light loads and rising to 500mV

p
at maximum output current. A second low current input voltage 1V or greater then the output voltage is required to achieve this
dropout. The AMS1508 can also be used as a single supply device.
New features have been added to the AMS1508: a remote Sense pin is brought out virtually eliminating output voltage
variations due to load changes. The typical load regulation, measured at the Sense pin, for a load current step of 100mA to 8A
is less than 1mV.
The AMS1508 series has fast transient response. The Adjust pin is brought out on fixed devices. To further improve the
transient response the addition of a small capacitor on the Adjust pin is recommended.
The AMS1508 series are ideal for generating processor supplies of 2V to 3V on motherboards where both 5V and 3.3V
supplies are available.

The AMS1508 devices are offered in 5 lead TO-220 and TO-263 (plastic DD) packages.

ORDERING INFORMATION: PIN CONNECTIONS

5 LEAD TO-263 5 LEAD TO-220

AMS1508CM AMS1508CT
AMS1508CM-1.5 AMS1508CT-1.5
AMS1508CM-2.5 AMS1508CT-2.5
AMS1508CM-2.85 AMS1508CT-2.85
AMS1508CM-3.0 AMS1508CT-3.0
AMS1508CM-3.3 AMS1508CT-3.3
AMS1508CM-3.5 AMS1508CT-3.5
AMS1508CM-5.0 AMS1508CT-5.0

PACKAGE TYPE O

PERATING JUNCTION

TEMPERATURE RANGE

0 to 125° C
0 to 125° C
0 to 125° C
0 to 125° C
0 to 125° C
0 to 125° C
0 to 125° C
0 to 125° C

•••• Post Regulators for Switching Supplies

5 LEAD TO-220

5

V

POWER

V

CONTROL

OUTPUT

ADJUST/GND

SENSE

4
3
2
1

FRONT VIEW

Advanced Monolithic Systems, Inc.

http://www.BDTIC.com/AMS

AMS1508

ABSOLUTE MAXIMUM RATINGS (Note 1)

V

Input Voltage 7V Soldering information

POWER

V

CONTROL

Input Voltage 13V Lead Temperature (25 sec)

265°C

Operating Junction Temperature Range Thermal Resistance
Control Section
Power Transistor
Storage temperature

0°C to 125°C

0°C to 150°C

- 65°C to +150°C

TO-220 package
TO-263 package

* With package soldering to 0.5in2 copper area over backside ground
plane or internal power plane φ
>40°C/W depending on mounting technique.

φ JA= 50°C/W

φ JA= 30°C/W*

can vary from 20°C/W to

JA

ELECTRICAL CHARACTERISTICS

Electrical Characteristics at I

= 0 mA, and TJ = +25°C unless otherwise specified.

LOAD

Parameter

Device Conditions Min Typ Max Units

Reference Voltage AMS1508 V

V
I

Output Voltage

AMS1508-1.5 V

V

AMS1508-2.5 V

V

AMS1508-2.85 V

V

AMS1508-3.0 V

V

AMS1508-3.3 V

V

AMS1508-3.5 V

V

AMS1508-5.0 V

V

Line Regulation AMS1508/-1.5/-2.5/

-2.85/-3.0/-3.3/-3.5/-5.0

Load Regulation

Minimum Load

AMS1508/-1.5/-2.5/

-2.85/-3.0/-3.3/-3.5/-5.0

AMS1508 V

I

0.8V≤ (V

V

I

Current

Control Pin Current

(Note 4)

Ground Pin Current

(Note 4)

AMS1508/-1.5/-2.5/

-2.85/-3.0/-3.3/-3.5/-5.0

AMS1508/-1.5/-2.5/

-2.85/-3.0/-3.3/-3.5/-5.0

V

I

V

I

Adjust Pin Current AMS1508 V

Current Limit

Ripple Rejection AMS1508/-1.5/-2.5/

AMS1508/-1.5/-2.5/

-2.85/-3.0/-3.3/-3.5/-5.0

-2.85/-3.0/-3.3/-3.5/-5.0

(VIN - V

V

I

Thermal Regulation AMS1508 TA = 25°C, 30ms pulse 0.002 0.020 %W

= 2.75V, V

CONTROL

= 2.7V to 12V, V

CONTROL

= 10mA to 8A

LOAD

= 4V, V

CONTROL

= 3V, V

CONTROL

= 5V, V

CONTROL

= 4V, V

CONTROL

= 5.35V, V

CONTROL

= 4.4V, V

CONTROL

= 5.5V, V

CONTROL

= 4.5V, V

CONTROL

= 5.8V, V

CONTROL

= 4.8V, V

CONTROL

= 6V, V

CONTROL

= 5V, V

CONTROL

= 7.5V, V

CONTROL

= 6.5V, V

CONTROL

= 10 mA , 1.5V≤ (V

LOAD

POWER

= V

CONTROL

= 10mA to 8A

LOAD

= 5V, V

CONTROL

= V

CONTROL

= 10mA to 8A

LOAD

= V

CONTROL

= 10mA to 8A

LOAD

= 2.75V, V

CONTROL

) = 5V

OUT

= V

CONTROL

= 4A

LOAD

POWER

POWER

POWER

POWER

POWER

POWER

- V

+ 2.5V, V

OUT

POWER

+ 2.5V, V

OUT

+ 2.5V, V

OUT

POWER

POWER

POWER

POWER

POWER

POWER

POWER

POWER

POWER

POWER

OUT

POWER

= V

=2V, I

POWER

=2.V, I
=2.3V, I

=3.3V, I
=3.3V, I

=3.35V, I

=3.7V, I

=3.5V, I
=3.8V, I

=3.8V, I
=4.1V, I

=4V, I
=4.3V, I

=5.5V, I
=5.8V, I

CONTROL

) ≤ 5.5V

POWER

=3.3V, V

POWER

POWER

= 2.05V, I

+ 2.5V, V

OUT

= 10mA

LOAD

=3.3V to 5.5V,

= 0mA

LOAD

= 0mA to 8A

LOAD

= 0mA

LOAD

= 0mA to 8A

LOAD

= 0mA

LOAD

= 0mA to 8A

LOAD

= 0mA

LOAD

= 0mA to 8A

LOAD

= 0mA

LOAD

= 0mA to 8A

LOAD

= 0mA

LOAD

= 0mA to 8A

LOAD

= 0mA

LOAD

= 0mA to 8A

LOAD

- V

) ≤ 12V

OUT

=V

+ 0.8V,

OUT

= 0V (Note 3)

ADJ

=V

+ 0.8V,

OUT

=V

+ 0.8V,

OUT

= 10mA

LOAD

= 1V

RIPPLE

1.243

1.237

1.491

1.485

2.485

2.475

2.821

2.833

2.982

2.970

3.280

3.235

3.479

3.430

4.930

4.950

7.1 8.0

60 80 dB

P-P

1.250

1.250

1.500

1.500

2.500

2.500

2.850

2.850

3.000

3.000

3.300

3.300

3.500

3.500

5.000

5.000

1 3

1

1.258

1.263

1.509

1.515

2.515

2.525

2.879

2.867

3.018

3.030

3.320

3.333

3.521

3.535

5.030

5.050

5

5 10

80 135

6 10

50 120

V
V

V
V

V
V

V
V

V
V

V
V

V
V

V
V

mV

mV

mA

mA

mA

µA

A

Thermal Resistance

T Package: Control Circuitry/ Power Transistor

Junction-to-Case

Advanced Monolithic Systems, Inc.

M Package: Control Circuitry/ Power Transistor

0.65/2.7

0.65/2.7

°C/W

°C/W

http://www.BDTIC.com/AMS

AMS1508

ELECTRICAL CHARACTERISTICS

Electrical Characteristics at I

= 0 mA, and TJ = +25°C unless otherwise specified.

OUT

Parameter

Device Conditions Min Typ Max Units

Dropout Voltage

Control Dropout
(V

Power Dropout
(V

CONTROL

POWER

- V

- V

OUT

OUT

)

AMS1508/-1.5/-2.5/

)

-2.85/-3.0/-3.3/-3.5/-5.0

AMS1508/-1.5/-2.5/

-2.85/-3.0/-3.3/-3.5/-5.0

Note 2

V

POWER

V

POWER

V

CONTROL

V

CONTROL

=V

=V

=V

=V

OUT

OUT

OUT

OUT

+ 0.8V, I

+ 0.8V, I

+ 2.5V, I

+ 2.5V, I

LOAD

LOAD

LOAD

LOAD

= 10mA

= 8A

= 10mA

= 8A

1.00

1.15

.10

.45

1.15

1.30

0.17

0.50

V

V

V

V

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: Unless otherwise specified V

OUT

= V

. For the adjustable device V

SENSE

ADJ

= 0V.

Note 3: The dropout voltage for the AMS1508 is caused by either minimum control voltage or minimum power voltage. The specifications represent the

minimum input/output voltage required to maintain 1% regulation.

Note 4: For the adjustable device the minimum load current is the minimum current required to maintain regulation. Normally the current in the resistor

divider used to set the output voltage is selected to meet the minimum load current requirement.

Note 5: The control pin current is the drive current required for the output transistor. This current will track output current with a ratio of about 1:100. The

minimum value is equal to the quiescent current of the device.

PIN FUNCTIONS

Sense (Pin 1): This pin is the positive side of the reference

voltage for the device. With this pin it is possible to Kelvin
sense the output voltage at the load.

Adjust (Pin 2): This pin is the negative side of the
reference voltage for the device. Adding a small bypass
capacitor from the Adjust pin to ground improves the
transient response. For fixed voltage devices the Adjust pin
is also brought out to allow the user to add a bypass
capacitor.

GND (Pin 2): For fixed voltage devices this is the bottom
of the resistor divider that sets the output voltage.

Output (Pin 3): This is the power output of the device.

V

CONTROL

ntrol circuitry of the device. The current flow into this

co

(Pin 4): This pin is the supply pin for the

pin will be about 1% of the output current. The voltage
at this pin must be 1.3V or greater than the output
voltage for the device to regulate.

V

(Pin 5): This pin is the collector to the power

POWER

device of the AMS1508. The output load current is
supplied through this pin. The voltage at this pin must
be between 0.1V and 0.8V greater than the output
voltage for the device to regulate.

Advanced Monolithic Systems, Inc.