1. FAN5904: Multi-mode Buck Converter for GSM/EDGE, CDMA, 3G & 4G PAs
September 2011

2. Introduction
Smartphones and most mobile handsets in market today are not only 3G and 4G-enabled but also backwards compatible to 2G technologies – GSM/GPRS/EDGE
Consumers are demanding that handsets have longer talk/usage times and don’t want to re-charge them frequently
Current power management solutions to support PAs are for 3G technologies
However there is a need to have DC-DC converter that can also support GSM, GPRS and EDGE
Key difference is that it needs to be able to handle up to 2.3A of continuous current

3. RF Power Mgmt for Today, Tomorrow and Yesterday
FAN5904
GSM 2G
GPRS
2.5G
EDGE
2.75G
WCDMA 3G
HSPA+
3.5G
LTE 4G
FAN5903

4. FAN5904 Buck Converter for GSM/EDGE, 3G & 4G PAs
Features
High Power Mode: GSM/EDGE PAMs
Up to 95% efficiency
Enables 35dBm output power
5µs VOUT step response to allow early GSM Tx power loop settling
3MHz PWM Mode
Low Power Mode: 3G/4G PAs
Supports 29dBm output power
10µs VOUT step response to allow early power loop settling
6MHz PWM for high POUT and PFM for low POUT PA operation
Bypass Mode
3A of load current
35mΩ integrated bypass FET
2.7V to 5.5V Input Voltage Range
VOUT range: 0.4V to 3.4V
Small Form Factor Inductor (470nH) and Capacitors
Pkg: 1.71x1.71mm WLCSP-16
Status
Samples & EVBs: Available Now
Production: Now

5. FAN5904 Optimization (1)
FAN5904 offers flexibility to trade efficiency for cost and solution size.
Current EVBs offer good efficiency in the smallest form factors.
3MHz/6MHz switching frequencies enable excellent regulation, low ripple, and fast transient response with small inductor size.
If efficiency is most important, inductor size may be increased at the cost of increased board space.
FAN5904
Exceeds GSM performance requirements with 2010 size 470nH inductor. Smallest available inductor package that can handle large current requirements mandated by 2G applications.

6. FAN5904 Application Diagram

7. FAN5904 Lower Heat Dissipation
20C
40C
25C
50C
30C
65C
VPA=2.37V
VBAT=3.7V
VBAT=4.2V
(Battery Charging)
3G PA w/ FAN5904
Thermal Profile
3G PA Only Thermal Profile

8. FAN5904: Extending Connection Time for Mobile Devices
Voice Calls
Data Transmit
Usage curve from GSMA’s “Battery Life Measurement Technique, v4.7
Assumes System Current Consumption = 100mA

9. FAN5904: Usage Time Summary WCDMA Mode
Type
Parameters
FAN5904
(minutes)
No FAN5904
Improvement
Absolute (minutes)
Percentage
Voice
Tx Time using 3 PA Power Modes
528
462 65
14%
Tx Time with PA in High Power Mode
515
297
218
73.2%
Data
436
348 88
25.4%
394
253
141
55.6%

10. FAN5904: Extending Connection Time for Mobile Devices
Voice 850MHz
Data 850MHz
*Usage curve from Microwave Journal article: Intelligent Power Management: A method to Improve 2G/3G Handset Talk Time, July 2007.
**Assumes System Current Consumption = 100mA

11. FAN5904: Usage Time Summary GSM/GPRS Mode
Type
Parameters
FAN5904
(minutes)
No FAN5904
Improvement
Absolute (minutes)
Percentage
Voice
Tx Time with 12.5% Duty Cycle in GSM Mode in Low Band
402
336 66
20%
Tx Time with 12.5% Duty Cycle in GSM Mode in High Band
494
416 78
19%
Data
Tx Time with 25% Duty Cycle in GPRS Mode in Low Band
279
234 45
Tx Time with 25% Duty Cycle in GPRS Mode in High Band
376
292 84
29%

12. Pricing & Availability
Fairchild Part Number
Package
Unit 1ku
Availability
FAN5904UC00X
WLCSP-16
$0.950
Now
FAN5904UC01X

13. Summary
Best in-class power management solutions to support all cellular standards
Meets specifications outlined in cellular standards
FAN5904 is a compact, high efficiency buck converter that provides these benefits:
More than 60 minutes of increased talk/usage time in 3G mode
More than 45 minutes of increased talk/usage time in 2G mode
Lowers heat dissipation by 40%
Smallest solution footprint
Smaller passive components due to 6MHz switching frequency
Lowers total cost of ownership
Reduce battery size, weight and cost

14. Technical Materials FAN5904 Datasheet
FAN5904 Product Overview
Evaluation Boards
Request via Sales Center
Samples

15. Marketing & Apps Contacts
Marketing Contact
Wayne Seto
Applications Support
Paul Finkel

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