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 Optimization (2) Efficiency Optimization
Smallest solution yields lowest cost.
Larger inductor may be used with FAN5904 to maximize efficiency.
Ripple voltage decreases with increasing inductor value, while larger inductor dimensions yields lower ESR. Low ripple and low ESR increase efficiency.
1µH 3030 inductor (DCR=43mW, Isat > 2.3A) improves efficiency at cost of increased board space.
Efficiency improvement typically 3-5%. More at low power

7. FAN5904 Implementation Options
Smallest Board Space – 470nH Inductor
3MHz/6MHz architecture allows small nH inductor to be used for both 2G and 3G applications.
TDK VLS nH DCR=40mW. Supports DC currents up to 2.5A.
Board Area w/ 2520 package 4.06mm x 5.11mm
Board Area w/ 2010 package 3.45mm x 5.11mm
2016 package also available with area less than 15mm2.
Optimal Efficiency – 1µH Inductor
Decreased ripple achieved with larger inductor reduces loss and improves efficiency.
Coilcraft XFL , 1µH, DCR=43mW.
Size 3mm x 3mm x 1mm
Efficiency is improved by 3-5% typically. Even more at low power.
Board Area w/ 3030 Inductor 3.42 mm x 6.80mm
FAN5904 Evaluation Board Footprint
w/ 470nH 2520 Inductor
FAN5904 Evaluation Board Footprint
w/ 1µH 3030 Inductor

8. FAN5904 Application Diagram

9. 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

10. 2G/3G/4G PA Thermal Issues
Common issue facing smartphones today is heat generated by PAs which causes these issues:
“Hot” or very warm mobile handset during voice calls and heavy data transmit functions
Thermal vias cannot dissipate all of the heat resulting in hotter PAs
Parameters
3G PA Only
3G PA + FAN5904
POUT = 17dBm
POUT = 0dBm
VPA (V)
3.700
0.984
0.718
IBATT (A)
0.167
0.015
0.058
0.004
Power Dissipation (W)
0.618
0.056
0.057
0.003
>16dBm (C/W)
16.0 -
Rise in Temperature (C)
9.9
0.9

11. FAN5904: Low Power Mode WCDMA/HSPA PAs

12. DC Efficiency Low Power Mode, VIN = 3.7V

13. DC Efficiency Low Power Mode, VIN = 3.7V

14. FAN5904 + 3G PA in WCDMA Mode Battery Current vs. Output Power

15. 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

16. 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%

17. Determining 3G PA VCC vs. POUT
Determine PA VCC for a Range of POUT
Determine acceptable Adjacent Channel Power Ratio
3GPP limit: 5MHz.
Add margin for component and voltage tolerances and manufacturing margins.
Limit of -39dBc used here.
Measure PA VCC vs. RF POUT for desired ACPR
Use a signal analyzer to measure ACPR
Start with PA VCC = 3.4V, then reduce VCC until ACPR = desired value
ACPR Measurement
-39.0
29.0
dBm
-39.2
PA VCC vs. POUT Results
Embedded Look Up Table
POUT
TX_AGC
VCON 29
256
1.300 27
244
1.160 25
198
0.944 23
176
0.780 22
150
0.560
POUT
(dBm)
PIN
PA VCC
(V)
IBATT
(mA)
VBATT
-5 MHz OFFSET
(dB)
+ 5 MHz OFFSET
29.0
3.4
3.25
518.40
3.7
-39.0
-39.2
28.2
2.2
465.12
-38.5
-40.3
27.0
1.2
2.90
369.34
-38.9
-40.7
26.1
0.4
2.61
300.05
-38.8
-40.6
25.0
-0.4
2.36
243.84
-40.4
23.9
-1.2
2.13
198.68
23.0
-1.9
1.95
165.11
-40.5
NEW
Fixed values added to calibration table. Not part of factory calibration.
Factory calibration
values.

18. Transmit Spurs Far Below WCDMA Modulation
Spurs << Mask for Low & High Power
WCDMA PA Output: 26.9dBm (PWM mode)
Modulation On
Modulation Off
High Output Power
DCDC in High Power mode (PWM)
Frequency automatically
decreases for longer duty
cycle (to provide more current)
Low Output Power
DCDC in Low Power mode
PFM mode
Frequency automatically
decreases to increase efficiency
Modulation On
Modulation Off
WCDMA PA Output: 5dBm (PFM mode)
No Spurs for Mid Power
Spurs < -87dBc
8dBm < POUT < 25dBm
(FSW = 3MHz or 6 MHz)

19. Transmit EVM: Almost No Change
W-CDMA EVM increased by 0.6% with FAN5904, but still far below limit.
RF POUT
MEASURED EVMRMS
EVM LIMIT
Lab Supply
FAN5904
W-CDMA Specification
29dBm
1.4%
(VCC = 3.4V)
1.9%
(VCC = 3.25V)
17.5%
16dBm
1.2%
1.8%
(VCC = 2.275V)
5dBm
1.3%
(VCC = 1.764V)

20. Rx Band Output Noise: No change
FAN5904 adds no noise in the receive bands. 2G
POUT [dBm]
PA VCC [V]
PA MODE
Rx Noise [dBm/Hz]
FAN5904
Lab Supply
34.0
3.315
GSM
-133
-134.5
30.5
2.236
-148.4
-148.5
5.0
0.487 3G
POUT [dBm]
PA VCC [V]
W-CDMA
PA MODE
Rx Noise [dBm/Hz]
FAN5904
Lab Supply
29.0
3.25
High Power
-135.1
-135.2
16.0
2.275
Med. Power
-148.5
5.0
1.764
Low Power
-6dB
N9010A Signal Analyzer
E4438C Signal Generator
VBIAS
VCC Rx
BAND Tx PA

21. FAN5904 Voltage Transition
WCDMA transition time
High POUT = 20µs
Low POUT = 5µs
Start-up transition time
20µs
WCDMA Specification for slot transition time
30µs

22. FAN5904: High Power Mode GSM/EDGE PAs

23. DC Efficiency High Power Mode, VIN = 3.7V

24. DC Efficiency High Power Mode, VIN = 5.0V

25. FAN5904 + GSM/EDGE PA in EDGE Mode Battery Current vs
FAN GSM/EDGE PA in EDGE Mode Battery Current vs. Output Power (GSM850)

26. FAN5904 + GSM/EDGE PA in EDGE Mode Battery Current vs
FAN GSM/EDGE PA in EDGE Mode Battery Current vs. Output Power (PCS1900)

27. FAN5904 + GSM/EDGE PA in GSM Mode Battery Current vs
FAN GSM/EDGE PA in GSM Mode Battery Current vs. Output Power (GSM850)

28. FAN5904 + GSM/EDGE PA in GSM Mode Battery Current vs
FAN GSM/EDGE PA in GSM Mode Battery Current vs. Output Power (PCS1900)

29. 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

30. FAN5904: Extending Connection Time for Mobile Devices
Voice 1900MHz
Data 1900MHz
*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

31. 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%

32. ORFS with FAN5904 EGSM900 (900MHz)
Procedure
Reduce VDCDC for POUT slightly greater than target
Reduce VRAMP to fine-tune POUT
Spectrum Analyzer set to EGSM limits
PIN = 0.7dBm, VBAT = 3.5V, Unmodified SKY77604 (Quad-band GSM/EDGE PAM)

33. ORFS with FAN5904 PCS1900 (1880MHz) Procedure
Reduce VDCDC for POUT slightly greater than target
Reduce VRAMP to fine-tune POUT
Spectrum Analyzer set to PCS limits
PIN = 0.7dBm, VBAT = 3.5V, Unmodified SKY77604 (Quad-band GSM/EDGE PAM)

34. Original factory calibration table.
Determining 2G PA VCC vs. POUT
Determine PA VCC for a Range of POUT
Determine acceptable ORFS margin
Customer consensus is 6dB of margin is sufficient
For example, -63dBc becomes -69dBc limit
Measure PA VCC vs. RF POUT for desired ORFS
Use a spectrum analyzer to measure ORFS (at fSW)
Start with PA VCC = 3.4V, then reduce VCC until POUT = Target POUT + 1dB (measured at the DCDC switching frequency).
Next, reduce VRAMP until POUT = Target POUT.
ORFS Measurement
PA VCC vs. POUT Results
Embedded Look Up Table
POUT
TX_AGC
VRAMP
VCON
34.0
256
1.740
1.326
32.0
244
1.300
1.111
30.5
198
1.200
0.894
28.0
176
1.062
0.728
26.0
150
1.000
0.585
POUT
(dBm)
PIN
PA VCC
(V)
IBATT
(mA)
VBATT
VRAMP
34.0
5.0
3.315
1350
3.7
1.740
32.0
2.778
932
1.300
30.5
2.236
650
1.200
28.0
1.82
450
1.062
26.0
1.462
324
1.000
24.0
1.205
236
0.920
NEW
New VRAMP and fixed VCON values added to calibration table. Not part of factory calibration.
Original factory calibration table.

35. Bill of Materials & Evaluation Board
Part Type
Case Size
Value
Vendor
Part Number
FAN5904
Inductor
2520
470nH
TDK
VLS252010T-R47N
Input Capacitor
0603
10µF
Panasonic
ECJ-1VB1A106M
Output Capacitor
0402
2* x 4.7µF
Murata
GRM155R60J475ME87D
FAN5904 Evaluation Board
Connect to PA
evaluation boards.
* One of the 4.7µF is replaced by the PA decoupling capacitor in most applications.
** C6 is for evaluation only and not needed for the actual application.

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

37. 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

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

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

40. Appendix

41. FAN5904 Timing Diagrams
GSM/EDGE
WCDMA

42. Test Configuration VCC VBATT IBATT FAN5904 -10dB PA VRAMP VBIAS
Power Mode Control
VRAMP
E4438C Signal Generator
VBIAS
VCC
N9010A Signal Analyzer
VCC
VRAMP and Peak Current for GSM PA
VCON
FAN5904
VBATT
Function Generator
Peak Current
IBATT
Power Supply

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