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FAN5902 -- 800mA Buck Converter for 3G RFPAs
May 2009
FAN5902 800mA Buck Converter for 3G RFPAs
Features
92% Efficient Synchronous Operation 2.7V to 5.5V Input Voltage Range VOUT Range from 0.4V to 3.4V (or VIN) Up to 800mA Output Current 20s Step Response 30s Bypass Transition Time 50m 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
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 VOUT=VBAT-250mV). The bypass 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 20s. 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.
Applications
Battery-Powered 3G RFPAs Multiband/Multimode WCDMA/CDMA Handset RF Transceivers RF PC Cards Pocket PC and PDAs with Communication Capabilities
Important
For complete performance specifications and datasheet, please contact a Fairchild Semiconductor sales representative.
Ordering Information
Part Number
FAN5902MPX FAN5902UCX
Operating Temperature Range
-40 to +85C -40 to +85C
Package
12-Lead, 3x3.5mm, Molded Leadless Package (MLP) 12-Bump, Wafer-Level Chip-Scale Package (WLCSP)
Eco Status
RoHS RoHS
Packing Method
Tape and Reel Tape and Reel
For Fairchild's definition of Eco Status, please visit: http://www.fairchildsemi.com/company/green/rohs_green.html.
(c) 2009 Fairchild Semiconductor Corporation FAN5902 * Rev. 1.0.2.short www.fairchildsemi.com
FAN5902 -- 800mA Buck Converter for 3G RFPAs
Application Diagrams
PVIN
10F
VOUTSNS VOUTSNS
0.4V < VOUT < VBAT 20mA < IOUT < 800mA
PVIN
AVIN
VBAT 2.7V to 5.5V From Processor
FAN5902
BPE N SYNC EN VCON
Figure 1.
470nH
SW PGND
VOUT 2.2F
From External DAC
AGND
FAN5902 Circuit
DCDC
PV IN
10 F 0603
50m
Bypass Slew Controller
V OUT_SNS V OUT_SNS
PV IN
VBATT 2.7V up to 5.5V
AV IN
Switcher
SW BPE N SY NC EN
Reference Controller
470nH
VOUT 2.2 F 0603
PGND
VCON
Bandgap
AGND
0.4V up to VIN Up to 800mA VOUT Dynamic Scaling
3
Supply
VMO D E
Bias
G P I O
D A C
RFIN
R FO U T
Duplexer
Base Process or
PDET
Power Detector
RX
R FPA
Figure 2.
(c) 2009 Fairchild Semiconductor Corporation FAN5902 * Rev. 1.0.2.short
Typical Application
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FAN5902 -- 800mA Buck Converter for 3G RFPAs
Pin Configurations
Figure 3. 12-Lead MLP (Top View)
Figure 4.
12-Bump WLCSP (Top View)
Pin Definitions
MLP Pin #
(*)
WLCSP Pin #
(*)
Name
AGND VOUTSNS EN VCON AVIN AGND BPEN SYNC PGND SW PVIN
Description
Analog ground, reference ground for the IC. Follow PCB routing notes for connecting this pin. Output voltage sense pin. Connect to VOUT to establish feedback path for regulation. Enables switcher when HIGH, shutdown mode when LOW. This pin should not be left floating. Analog control input from an external D-to-A converter. Analog bias supply voltage input. Connect to PVIN. Connect to analog ground. 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. Switching node of the internal MOSFET switches. Connect to output inductor. Supply voltage input to the internal MOSFET switches. Connect to input power source.
(*) Pinout available upon request
(c) 2009 Fairchild Semiconductor Corporation FAN5902 * Rev. 1.0.2.short
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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
VIN TJ TSTG TL JC AVIN, PVIN Voltage On Any Other Pin Junction Temperature Storage Temperature
Parameter
Min.
-0.3 -0.3 -40 -65
Max.
6.0 AVIN+0.3 +125 +150 +260 5 30
Unit
V C C C C/W C/W
Lead Soldering Temperature (10 Seconds) Thermal Resistance, Junction to Tab
(1) (1)
MLP Package WLCSP Package
JC Thermal Resistance, Junction to Case 1. Refer to JA data below.
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
VCC VOUT IOUT L CIN COUT TA TJ Supply Voltage Range Output Voltage Range Output Current Inductor Input Capacitor
(2) (2)
Parameter
Min.
2.7 0.4 20
Typ.
Max.
5.5 VIN 800
Unit
V V mA H F
0.47 10 2.2 -40 -40 4.7 10.0 +85 +125
Output Capacitor
F C C
Operating Ambient Temperature Range Operating Junction Temperature Range
Notes: 2. A high input capacitor value is required for limiting input voltage drop during bypass transitions or during large output voltage transitions. Ensure the input capacitor value is greater than the output capacitor's. See the inrush current specifications below. 3. Refer to application note AN-6087 for more details.
Dissipation Ratings(4)
Package
Molded Leadless Package (MLP) Wafer-Level Chip-Scale Package (WLCSP)
JA
(4)
(5) (5)
Power Rating (5) at TA 25C
2050mW 900mW
Derating Factor > TA=25C
21mW/C 9mW/C
49C/W
110C/W
Notes: 4. Thermal Resistance, Junction-to-Ambient, measured according to JEDEC 2S2P PCB (and zero air flow). JA for JEDEC 1S0P PCB (and zero air flow) = 210C/W. 5. Maximum power dissipation is a function of TJ(max), JA, and TA. The maximum allowable power dissipation at any allowable ambient temperature is PD=[TJ(max) - TA ] / JA.
(c) 2009 Fairchild Semiconductor Corporation FAN5902 * Rev. 1.0.2.short
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FAN5902 -- 800mA Buck Converter for 3G RFPAs
Typical Performance Characteristics
Typical performance at 25C.
500
30
IBAT [mA]
PAE [%]
PAE with FAN5902
250
IBAT without FAN5902
15
PAE without FAN5902
0 0
IBAT with FAN5902
0
30
POUT [dBm]
15
0
POUT [dBm]
15
30
Figure 5. Comparison of RF PA Current Consumption with and without FAN5902
Figure 6. Comparison of RFPA Power Added Efficiency with and without FAN5902
Figure 7. Rise Times for 300mV, 500mV, and 2V VOUT COUT = 2.2F (VIN=3.7V)
Figure 8. Rise Times for 300mV, 500mV, and 2V VOUT COUT = 2.2F (VIN=3.7V)
(c) 2009 Fairchild Semiconductor Corporation FAN5902 * Rev. 1.0.2.short
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FAN5902 -- 800mA Buck Converter for 3G RFPAs
Physical Dimensions
2X
0.10 A
3.50
A B
2.65 2.60
0.85
PIN#1 IDENT
3.00 2.84
TOP VIEW
0.10 B
2X
1.85 1.05 0.85 (0.2)
0.8 MAX
0.10 C
LAND PATTERN RECOMMENDATION
0.08 C
0.05 0.00
SIDE VIEW
2.60+/-0.05 (0.38)
C
SEATING PLANE
6
1.60+/-0.05
PIN#1 IDENT
1
0.25+/-0.05
0.45+/-0.05 (12X)
12
0.50
7
0.25+/-0.05 (12X)
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
BOTTOM VIEW
0.10 0.05
CAB C
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. Please note the revision and/or date on the drawing and contact a Fairchild Semiconductor representative to 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.fairchildsemi.com/packaging/.
(c) 2009 Fairchild Semiconductor Corporation FAN5902 * Rev. 1.0.2.short
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FAN5902 -- 800mA Buck Converter for 3G RFPAs
Physical Dimensions (Continued)
BALL A1 INDEX AREA 0.03 C
E
A B
(O0.25) Cu PAD
0.50
2X
D
A1
0.50
1.00
(O0.35) SOLDER MASK OPENING
TOP VIEW
0.03 C
2X
RECOMMENDED LAND PATTERN (NSMD)
0.06 C
0.05 C
0.625 0.539
0.3320.018
0.2500.025
D
C
SEATING PLANE
SIDE VIEWS
(X)+/-.018
0.50 0.005 CAB
12 X O0.315 +/- .025
D
0.50
C B A 12 3
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
(Y)+/-.018
BOTTOM VIEW
PRODUCT DATASHEET. F. BALL COMPOSITION: Sn95.5Ag3.9Cu0.6 SAC405 ALLOY 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. Please note the revision and/or date on the drawing and contact a Fairchild Semiconductor representative to 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.fairchildsemi.com/packaging/.
(c) 2009 Fairchild Semiconductor Corporation FAN5902 * Rev. 1.0.2.short
www.fairchildsemi.com 7
FAN5902 -- 800mA Buck Converter for 3G RFPAs
(c) 2009 Fairchild Semiconductor Corporation FAN5902 * Rev. 1.0.2.short
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