Fairchild Semiconductor FAN1581 Datasheet

www.fairchildsemi.com

FAN1581

5A Adjustable/Fixed Ultra Low Dropout
Linear Regulator

Features

• Ultra Low dropout voltage, 0.4V typical at 5A

• 1.2V Versions available

• Remote sense operation

•Fast transient response

• Load regulation: 0.05% typical

• 0.5% initial accuracy

• On-chip thermal limiting

• 5-pin SPAK, TO-263, TO-252 and TO-220 packages

Applications

• Pentium

•PowerPC

• Pentium support of GTL+ bus supply

•Low voltage logic supply

• Embedded Processor supplies

• Split plane regulator

•New 2.5V and 1.8V Logic Families

• DDR Termination Supply

®

Processors

™

, AMD K5 and K6 processors

Typical Applications

Description

The FAN1581, FAN1581x12, FAN1581-1.5, and FAN1581-

2.5 are ultra-low dropout regulators with 5A output current
capability. These devices have been optimized for low volt­age applications including V
sient response and minimum input voltage are critical. The
FAN1581 is ideal for low voltage microprocessor applica­tions requiring a regulated output from 1.3V to 5.7V with a
power input supply of 1.75V to 6.5V. The FAN1581-1.5
offers fixed 1.5V with 5A current capabilities for GTL+ bus
V

termination. Additionally, the FAN1581x12 offers fixed

TT

1.2V output for CPU Bus termination. The FAN1581-2.5
offers fixed 2.5V with 5A current capability for logic IC
operation and processors while minimizing the overall power
dissipation.

Current limit ensures controlled short-circuit current. On-chip
thermal limiting provides protection against any combination
of overload and ambient temperature that would create exces­sive junction temperatures.

The FAN1581 series regulators are available in the 5-pin
SPAK, TO-263, TO-252 and TO-220 packages.

bus termination, where tran-

TT

V

= 3.3V

IN

10µF

V

= 3.3V

IN

10µF

V

= 5V

CNTL

1µF

V

= 3.3V

IN

10µF

V

= 5V

CNTL

1µF

Pentium is a registered trademark of Intel Corporation. PowerPC is a trademark of IBM Corporation.

+

+

+

+

V

INVSENSE

FAN1581

V

CNTL

Adj

V

INVSENSE

FAN1581M12

V

CNTL

Adj

V

OUT

124Ω

86.6Ω

V

OUT

120Ω

+

2.1V at 5A

22µF

1.2V at 5A

22µF

V

V

V

CNTL

CNTL

IN

= 5V

1µF

= 5.75V

10µF

= 12V

1µF

+

+

+

+

V

INVSENSE

FAN1581–2.5

V

V

V

V

CNTL

GND

INVSENSE

FAN1581

V

CNTL

Adj

OUT

OUT

+

22µF

+

124Ω

374Ω

22µF

REV. 1.1.8 4/7/03

2.5V at 5A

5V at 5A

FAN1581 PRODUCT SPECIFICATION

Pin Assignments

FAN1581M-1.5, -2.5 FAN1581M

FRONT VIEW

FRONT VIEW

FAN1581P

FRONT VIEW

FAN1581P-1.5, -2.5

FRONT VIEW

FAN1581D

FRONT VIEW

FAN1581D-1.5, -2.5

FRONT VIEW

4 5

123

S

*With package soldered to 0.5 square inch copper area over backside ground plane or internal power plane, θJA can vary from

IN

OUT

GND

CNTL

5-Lead Plastic TO-263

=3°C/W*

Θ

JC

Tab is out.

30 °C/W to more than 40 °C/W. Other mounting techniques can provide a thermal resistance lower than 30 °C/W.

4 5

123

S

ADJ

OUT

CNTL

FRONT VIEW

12345

5-Lead TO-220

=3°C/W* Tab is VOUT.

Θ

JC

12345

IN

FAN1581T

FAN1581T12

S

OUT

ADJ

S

ADJ

OUT

5-Lead Plastic SPAK

IN

CNTL

12345 1 2 3 4 5 1 2 3 4 5

S

IN

CNTL

Θ

=2°C/W*

JC

Tab is out.

GND

OUT

IN

CNTL

S

ADJ

5-Lead Plastic TO-252 DPAK

OUT

IN

CNTL

=3°C/W*

Θ

JC

Tab is out.

S

OUT

GND

CNTL

Pin Definitions

Pin

Number Pin Name Pin Function Descrition

1

2

3VOUT

4 VCNTL Control Voltage. This pin draws small-signal power to control the FAN1581 circuitry.

5 VIN

VSense Remote Voltage Sense . Connect this pin to the load to permit true remote sensing and

avoid trace drops.

ADJ/GND Adjust or Ground. On the FAN1581, this pin forms the feedback to determine the output

voltage. On the FAN1581-1.5 and -2.5, connect this pin to ground.

Output Voltage. This pin and the tab are output.

Connect to a voltage higher than VIN, as shown in the applications circuits.

Input Voltage.

IN

Internal Block Diagram

Thermal

Shutdown

Vref

2

4

, Control

V

CNTL

Current

Limit

Voltage Loop

Amplifier

5

Vin, Power

3

Output

1

Sense

2

Adj

REV. 1.1.8 4/7/03

≤

≤

≤

≤

≤

≤

≤

≤

≤

≤

≤

≤

PRODUCT SPECIFICATION FAN1581

Absolute Maximum Ratings

Parameter Min. Max. Unit

V
V

IN

CNTL

7V

13.2 V
Operating Junction Temperature Range 0 125 °C
Lead Temperature (Soldering, 10 sec.) 300 °C
Storage Temperature Range -65 150 °C

Electrical Characteristics

T

=25°C, V

J

The • denotes specifications which apply over the specified operating temperature range.

Reference Voltage

FAN1581x12
Reference Voltage

FAN1581x12
Adjustable Output Voltage 3V ≤ V

Output Voltage
Output Voltage
Line Regulation

Load Regulation

Dropout Voltage Minimum
(V

CNTL

Dropout Voltage Minimum
(V

–V

IN

Dropout Voltage Minimum V

Current Limit V
Control Pin Current V

Adjust Pin Current
Minimum Load Current V
Ripple Rejection V

Thermal Resistance, Junction to
Case

Thermal Regulation T
Thermal Shutdown 150 °C

= V

, V

OUT

= 0V unless otherwise specified.

S

ADJ

Parameter Conditions Min. Typ. Max. Units

–V

OUT

OUT

)

3

3

4

5

1,2

1,2

)

IN

3

V

= 2.0V, V

IN

I

= 10mA

OUT

2.05V ≤ V

2.7V ≤ V
10mA ≤ I

10mA ≤ I
3V ≤ V

5.1V ≤ V

1.75V ≤ V
I

OUT

V

IN

10mA ≤ I
V

IN

V

CNTL

I

OUT

V

CNTL

I

OUT

IN

IN

I

OUT

V

IN

IN

IN

C

OUT

IN

CNTL

OUT

7V (function of Vout),

IN

OUT

7V, 10mA ≤ I

IN

IN

IN

= 10mA

= 2.1V, V

OUT

= 2.05V, ∆ V

= 2.75V, ∆ V

= 5A

= 2.75V, ∆ V

= 5A
= 2.05V, V
= 2.05V, V

= 10mA
= 2.05V, V
= 3.3V, V

= 3.75V, V

= 22µF Tantalum, I

TO-263
SPAK

= 25°C, 30ms pulse 0.002 0.02 %/W

A

CNTL

5.5V,

= 2.75V,

1.243

1.164

• 1.237

1.250

1.200

1.250

12V,

5A

1.164

1.200

• Vref 1.5 5.7 V

5A

5A • 1.47 1.5 1.53 V

OUT

7V, 10mA ≤ I

5.5V, 2.5V ≤ V

= 2.75V,

CNTL

5A • 2.474 2.5 2.526 V

OUT

CNTL

12V,

•13mV

•15mV

5A

= 1%, I

REF

= 1%,

REF

= 1%,

REF

= 2.75V • 5.2 A

CNTL

= 2.75V,

CNTL

= 2.75V • 50 120 µA

CNTL

= 5V • 5.0 10 mA

CNTL

= 3.75V, f = 120Hz,

CNTL

= 5A • 1.05 1.18 V

OUT

0.4 0.5 V

• 0.5 0.6 V

•26mA

60 80 dB

= 2.5A

OUT

3
2

1.257

1.236VV

1.263

1.236VV

°C/W

Notes:

1. See thermal regulation specifications for changes in output voltage due to heating effects. Load and line regulation are
measured at a constant junction temperature by low duty cycle pulse testing.

2. Line and load regulation are guaranteed up to the maximum power dissipation (18W). Power dissipation is determined by
input/output differential and the output current. Guaranteed maximum output power will not be available over the full input/
output voltage range.

3. FAN1581 only.

4. FAN1581-1.5 only.

5. FAN1581-2.5 only.

REV. 1.1.8 4/7/03

3

FAN1581 PRODUCT SPECIFICATION

Typical Perfomance Characteristics

1.0

0.9

0.8

0.7

0.6

0.5

0.4

0.3

0.2

DROPOUT VOLTAGE (V)

0.1

0.0

1.275

1.270

1.265

1.260

1.255

1.250

1.245

1.240

1.235

REFERENCE VOLTAGE MINIMUM LOAD CURRENT (mA)

1.230

1.225

T=25°C

01 2 435

OUTPUT CURRENT (A)

Dropout Voltage vs. Output Current Load Regulation vs. Temperature

FAN1581, 1.25V only

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

Reference Voltage vs. Temperature Output Voltage vs. Temperature

T=0°C

T=125°C

0.10

0.05

0

-0.05

-0.10

-0.15

OUTPUT VOLTAGE DEVIATION (%)

-0.20

3.70

3.65

3.60

3.55

3.50

3.45

3.40

3.35

3.30

OUTPUT VOLTAGE (V)

3.25

3.20

175

∆Ι=5A

-75 -50 -25 25 50 75 100 125 150 1750

V

set with

OUT

1% resistors

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

JUNCTION TEMPERATURE (°C)

V

= 3.3V

OUT

Note:

1

1. FAN1581 Only

175

10

8

6

4

2

0

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

Mimimum Load Current vs. Temperature Adjust Pin Current vs. Temperature

175

4

100

90

80

70

60

50
40

30
20

10

ADJUST PIN CURRENT (µA)

0

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

Note:

1. FAN1581 Only

175

REV. 1.1.8 4/7/03