Datasheet FAN5902 Datasheet (Fairchild)

FAN5902 800mA Buck Converter for 3G RFPAs

FAN5902 — 800mA Buck Converter for 3G RFPAs FAN5902 — 800mA Buck Converter for 3G RFPAs

May 2009

Features

 92% Efficient Synchronous Operation  2.7V to 5.5V Input Voltage Range  V

Range from 0.4V to 3.4V (or VIN)

OUT

 Up to 800mA Output Current  20µs Step Response  30µs Bypass Transition Time  50mΩ Integrated Bypass FET with Controlled Slew

Rate for Low Battery Voltage Operation

 6MHz PWM Operation Allows 470nH Small Form

Factor Inductor

 100% Duty Cycle for Low Dropout Operation  Thermal Shutdown  Input Under-Voltage Lockout  12-Lead MLP (0.8mm Maximum)  12-Bump WLCSP

Applications

 Battery-Powered 3G RFPAs  Multiband/Multimode WCDMA/CDMA Handset RF

Transceivers

 RF PC Cards  Pocket PC and PDAs with Communication

Capabilities

Description

The FAN5902 is a high-efficiency, low-noise, synchronous, step-down DC-to-DC converter designed for powering the radio frequency power amplifiers (RFPA) in 3G mobile handsets and other mobile applications. It provides up to 800mA of output current over an input voltage range of 2.7V to 5.5V. The output voltage can be dynamically adjusted from 0.4V up to

3.4V, proportional to an analog input voltage ranging from 0.2V to 1.7V provided by an external DAC. This allows supplying the RFPA with the voltage level that provides optimum Power Added Efficiency (PAE).

An integrated bypass FET automatically switches on when the battery voltage drops too close to the output voltage (when V transition is controlled by a slew rate controller to limit the inrush current and reduce the RFPA gain deviation.

The FAN5902 offers fast transition times, allowing changes to the output voltage in less than 20µs.

The FAN5902 operates at 6MHz, enabling the use of a small, low-value inductor of 470nH. A current-mode control loop with fast transient response ensures excellent line and load regulation.

The FAN5902 improves the RFPA power efficiency and increases the talk/connection time in 3G handsets.

The FAN5902 is available in a 12-lead MLP package and 12-bump WLCSP.

OUT=VBAT

-250mV). The bypass

Important

For complete performance specifications and datasheet, please contact a Fairchild Semiconductor sales representative.

Ordering Information

Part Number

FAN5902MPX -40 to +85°C

FAN5902UCX -40 to +85°C

For Fairchild’s definition of Eco Status, please vis it: http://www.fairchildsemi.com/company/green/rohs_green.html.

Operating

Temperature Range

Package

12-Lead, 3x3.5mm, Molded Leadless Package (MLP)

12-Bump, Wafer-Level Chip-Scale Package (WLCSP)

Eco Status

RoHS Tape and Reel

RoHS

Packing

Method

Tape and Reel

FAN5902 — 800mA Buck Converter for 3G RFPAs

Application Diagrams

10μF

V

BAT

2.7V to

5.5V

From Processor

From External DAC

PVIN

PVIN VOUTSNS

PVIN

VOUTSNS

AVIN

FAN5902

BPE N

SW

PGND

SYNC

EN

AGND

VCON

Figure 1. FAN5902 Circuit

DCDC

V

50m

OUT_SNS

0.4V < V

20mA < I

470nH

OUT

< V

BAT

< 800mA

V

2.2μF

OUT

10 F 0603

V

BATT

2.7V up to 5.5V

3

G P

I

O

Processor

Base

PVIN

AVIN

BPE N

SYNC

EN

VCON

D A C

Bypass Sl ew

Controller

Swi tcher

Controller

SW

PGND

V

Reference

Bandgap

V

MOD E

R

FIN

P

DET

Bias

Power

Detector

AGND

RFPA

Figure 2. Typical Application

OUT_SNS

470n H

Supply

V

OUT

2.2 F 0603

0.4V up to V Up to 800mA

V

Dynamic

Scaling

R

FOUT

Duplexer

RX

IN

OUT

Pin Configurations

Figure 3. 12-Lead MLP

(Top View)

FAN5902 — 800mA Buck Converter for 3G RFPAs

Figure 4. 12-Bump WLCSP

(Top View)

Pin Definitions

MLP

Pin #

(*) (*) AGND

VOUTSNS

EN

VCON Analog control input from an external D-to-A converter.

AVIN Analog bias supply voltage input. Connect to PVIN.

AGND Connect to analog ground.

BPEN

SYNC

PGND

SW Switching node of the internal MOSFET switches. Connect to output inductor.

PVIN

(*) Pinout available upon request

WLCSP

Pin #

Name Description

Analog ground, reference ground for the IC. Follow PCB routing notes for connecting this pin.

Output voltage sense pin. Connect to V regulation.

Enables switcher when HIGH, shutdown mode when LOW. This pin should not be left floating.

Force bypass transistor when HIGH; auto-bypass when LOW. This pin should not be left floating

External clock synchronization input and PFM lockout. When SYNC remains HIGH, the DC-to-DC does not allow PFM mode. Tie SYNC to AGND if not used.

Power ground of the internal MOSFET switches. Follow routing notes for connections between PGND and AGND.

Supply voltage input to the internal MOSFET switches. Connect to input power source.

to establish feedback path for

OUT

FAN5902 — 800mA Buck Converter for 3G RFPAs

Absolute Maximum Ratings

Stresses exceeding the absolute maximum ratings may damage the device. The device may not function or be operable above the recommended operating conditions and stressing the parts to these levels is not recommended. In addition, extended exposure to stresses above the recommended operating conditions may affect device reliability. The absolute maximum ratings are stress ratings only.

Symbol Parameter Min. Max. Unit

VIN

TJ Junction Temperature -40 +125 °C

T

STG

TL Lead Soldering Temperature (10 Seconds) +260 °C

θJC Thermal Resistance, Junction to Tab

θJC Thermal Resistance, Junction to Case

1. Refer to θJA data below.

AVIN, PVIN -0.3 6.0

Voltage On Any Other Pin -0.3 AV

IN

+0.3

V

Storage Temperature -65 +150 °C

(1)

MLP Package 5 °C/W

(1)

WLCSP Package 30 °C/W

Recommended Operating Conditions

The Recommended Operating Conditions table defines the conditions for actual device operation. Recommended operating conditions are specified to ensure optimal performance to the datasheet specifications. Fairchild does not recommend exceeding them or designing to Absolute Maximum Ratings.

Symbol Parameter Min. Typ. Max. Unit

VCC

V

OUT

I

OUT

CIN

C

OUT

TA

TJ

Notes:

2. A high input capacitor value is required for limiting input voltage drop during bypass transitions or during large

3. Refer to application note AN-6087 for more details.

Dissipation Ratings

Molded Leadless Package (MLP) 49ºC/W

Wafer-Level Chip-Scale Package (WLCSP) 110ºC/W

Notes:

4. Thermal Resistance, Junction-to-Ambient, measured according to JEDEC 2S2P PCB (and zero air flow). θJA for

5. Maximum power dissipation is a function of T

Supply Voltage Range 2.7 5.5 V

Output Voltage Range 0.4 V

Output Current 20 800 mA

L

Inductor 0.47 µH

Input Capacitor

Output Capacitor

(2)

10 µF

(2)

2.2 4.7 10.0 µF

V

IN

Operating Ambient Temperature Range -40 +85 °C

Operating Junction Temperature Range -40 +125 °C

output voltage transitions. Ensure the input capacitor value is greater than the output capacitor’s. See the inrush current specifications below.

(4)

Package θ

(4)

JA

(5)

2050mW 21mW/ºC

(5)

900mW 9mW/ºC

Power Rating

at T

≤ 25°C

A

(5)

Derating Factor

> TA=25ºC

JEDEC 1S0P PCB (and zero air flow) = 210°C/W.

, θJA, and TA. The maximum allowable power dissipation at any

allowable ambient temperature is P

D

=[T

J(max)

- TA ] / θJA.

J(max)

Typical Performance Characteristics

Typical performance at 25°C.

500

FAN5902 — 800mA Buck Converter for 3G RFPAs

30

PAE with FAN5902

250

[mA]

BAT

I

without FAN5902

BAT

I

wi th FAN5902

P

OUT

BAT

[dBm]

0

01530

Figure 5. Comparison of RF PA Current Consumption

with and without FAN5902

15

PAE [%]

PAE without FAN5902

0

01530

P

[dBm]

OUT

Figure 6. Comparison of RFPA Power Added

Efficiency with and without FAN5902

Figure 7. Rise Times for 300mV, 500mV, and 2V ΔV

C

= 2.2µF (VIN=3.7V)

OUT

Figure 8. Rise Times for 300mV, 500mV, and 2V

ΔV

OUT COUT

= 2.2µF (VIN=3.7V)

Physical Dimensions

2X

0.10

A

3.50

FAN5902 — 800mA Buck Converter for 3G RFPAs

A

B

2.60

PIN#1 IDENT

0.10

0.08

PIN#1 IDENT

0.25+/-0.05

C

0.05

0.00

0.45+/-0.05 (12X)

TOP VIEW

0.8 MAX

SIDE VIEW

2.60+/-0.05

1

0.50

BOTTOM VIEW

(0.38)

6

712

0.25+/-0.05 (12X)

3.00

0.10

B

2X

(0.2)

C

SEATING PLANE

1.60+/-0.05

0.10 CAB

0.05

C

2.65

1.85

1.05

0.85

2.84

LAND PATTERN RECOMMENDATION

NOTES: A. CONFORMS TO JEDEC MO-229 VARIATION WFED-2. B. DIMENSIONS ARE IN MILLIMETERS C. DIMENSIONS AND TOLERANCES PER ASME Y14.5M, 1994 D. LANDPATTERN RECOMMENDATION IS BASED ON IPC 7351 DESIGN GUIDELINES E. LANDPATTERN EXTENSION TO INCLUDE CENTER PAD TABS IS OPTIONAL F. FILENAME AND REV: MKT-MLP12DREV1

Figure 9: 3x3.5mm 12-Lead MLP

Package drawings are provided as a service to customers considering Fairchild components. Drawings may change in any manner without notice. Pl ease note the revision and/or date on t he drawing and contact a Fairchild Semiconductor representative t o verify or obtain the most recent revision. Package specifications do not expand the terms of Fairchild’s worldwide terms and conditions, specifically the warranty therein, which covers Fairchild products.

Always visit Fairchild Semiconductor’s online packaging area for the most recent package drawings:

http://www.fairchildsem i.com/p ackagi ng/

.

Physical Dimensions (Continued)

FAN5902 — 800mA Buck Converter for 3G RFPAs

BALL A1 INDEX AREA

0.03 C

2X

E

A

B

(Ø0.25) Cu PAD

A1

0.50

1.00

(Ø0.35)

D

0.50

SOLDER MASK OPENING

C

2X

0.03 C

RECOMMENDED LAND PATTERN (NSMD)

0.332±0.018

0.250±0.025

0.05 C

D

TOP VIEW

C

0.06

0.625

0.539

SEATING PLANE

SIDE VIEWS

(X)+/-.018

0.50

0.005 CAB

12 X Ø0.315 +/- .025

A. NO JEDEC REGISTRATION APPLIES

B. DIMENSIONS ARE IN MILLIMETERS.

C. DIMENSIONS AND TOLERANCES PER

ASME Y14.5M, 1994

D

DATUM C, THE SEATING PLANE, IS DEFINED BY THE SPHERICAL CROWNS OF THE BALLS.

F

FOR DIMENSIONS D, E, X, AND Y SEE PRODUCT DATASHEET.

F. BALL COMPOSITION: Sn95.5Ag3.9Cu0.6

SAC405 ALLOY

(Y)+/-.018

0.50

12

BOTTOM VIEW

D

C

B A

3

G. DRAWING FILENAME: MKT-UC012AArev2

Figure 10. 12-Bump WLCSP

Package drawings are provided as a service to customers considering Fairchild components. Drawings may change in any manner without notice. Pl ease note the revision and/or date on t he drawing and contact a Fairchild Semiconductor representative t o verify or obtain the most recent revision. Package specifications do not expand the terms of Fairchild’s worldwide terms and conditions, specifically the warranty therein, which covers Fairchild products.

Always visit Fairchild Semiconductor’s online packaging area for the most recent package drawings:

http://www.fairchildsem i.com/p ackagi ng/

.

FAN5902 — 800mA Buck Converter for 3G RFPAs

Datasheet FAN5902 Datasheet (Fairchild)

Specifications and Main Features

Frequently Asked Questions

User Manual