FAN5904UC00X - Fairchild Semiconductor

FAN5904
Multi-Mode Buck Converter for GSM/EDGE, 3G/3.5G and 4G PAs
Features
 2.7 V to 5.5 V Input Voltage Range
 VOUT Range from 0.40 V to 3.50 V (or VIN)
 Single 470 nH Small Form Factor Inductor
 35 mΩ Integrated Bypass FET
 100% Duty Cycle for Low Dropout Operation
 Input Under-Voltage Lockout / Thermal Shutdown
 1.71 mm x 1.71 mm, 16-Bump, 0.4 mm Pitch WLCSP
 High Power PWM Mode
o
o
o
o

Up to 95% Efficient Synchronous Operation in
High POUT Conditions
Output current up to 2.3 A
10 µs Output Voltage Step Response for Early
GSM Tx Power-Loop Settling
3MHz PWM Mode
Low Power Auto Mode
Up to 95% Efficient Synchronous Operation at
Higher POUT Conditions
o Output Current up to 1.2 A
o 10 µs Output Voltage Step Response for Early Tx
Power-Loop Settling
o 6 MHz PWM Operation at High Power and PFM
Operation at Low Power
o

o
Bypass Mode
Up to 3 A Load Current
Applications
 Dynamic Supply Bias for Polar or Linear GSM/EDGE
PAs and 3G/3.5G and 4G PAs

Description
The FAN5904 is a high-efficiency, low-noise, synchronous,
step-down, DC-DC converter optimized for powering Radio
Frequency (RF) Power Amplifiers (PAs) in handsets and
other mobile applications. In High-Power Mode, GSM Tx
power is enabled. In Low-Power Mode, up to 3.0 W is
supported, enabling up to 29 dBm output power for 3G/3.5G
and 4G platforms.
The output voltage may be dynamically adjusted from
0.40 V to 3.50 V, proportional to an analog input voltage
VCON ranging from 0.16 V to 1.40 V, optimizing poweradded efficiency. Fast transition times of less than 10 µs are
achieved, allowing excellent inter-slot settling.
An integrated bypass FET is automatically enabled when
the battery voltage and voltage drop across the DC-DC
PMOS device are within a set voltage range of the desired
output voltage (VOUT = VBAT - VPMOS - VBP_TH). This dynamic
bypass feature enables the FAN5904 to support heavy load
currents under the most stringent VSWR conditions while
maintaining high efficiency and superior spectral
performance. The bypass FET may also be enabled by
providing a VCON voltage nominally greater than or equal
to 1.5 V or by driving BPEN high.
The FAN5904 operates in PWM Mode with a 6 MHz
switching frequency in Low-Power Mode and at 3 MHz in
High-Power Mode, which limits high-frequency spur levels.
It uses a single, small form factor inductor of 470 nH. In
addition, PFM operation is allowed in Low-Power Mode to
improve efficiency at low load currents.
The FAN5904UC00X option allows PFM Mode only when
VOUT is less than 1 V, while the FAN5904UC01X permits
PFM Mode at higher voltages for applications that can
tolerate larger output ripple and that demand optimal low-tomoderate load current efficiency.
Dynamic Supply Bias for GSM/EDGE Quad Band
Amplifiers for Mobile Handsets and Data Cards
Ordering Information
Part Number
LPM Mode PFM
FAN5904UC00X
VOUT < 1 V
FAN5904UC01X
All VOUT
© 2011 Fairchild Semiconductor Corporation
FAN5904 • Rev. 3.0.7
Output Voltage
0.4 V to PVIN
Temperature
Range
Package
Packing
1.71 mm x 1.71 mm, 16-Bump
-40°C to +85°C 0.4 mm Pitch, Wafer-Level
Tape and Reel
Chip-Scale Package (WLCSP)
www.fairchildsemi.com
FAN5904 — Multi-Mode Buck Converter for GSM/EDGE, 3G/3.5G and 4G PAs
October 2013
FAN5904 — Multi-Mode Buck Converter for GSM/EDGE, 3G/3.5G and 4G PAs
Block Diagrams
Figure 1. Typical Application
Figure 2. Simplified Block Diagram
© 2011 Fairchild Semiconductor Corporation
FAN5904 • Rev. 3.0.7
www.fairchildsemi.com
2
Figure 3. Bumps Face Down – Top-Through View
Figure 4. Bumps Face Up
Pin Definitions
Pin #
Name
Description
C1
AGND
A4, B4
FB
D4
FB_SNS
C2
EN
D2
VCON
Analog control pin. Shield signal routing against noise.
D1
AVIN
Analog supply voltage input. Connect to PVIN.
C3
BPEN
Force bypass when HIGH; Auto bypass when LOW. This pin should not be left floating.
C4
SYNC
External clock synchronization input. When SYNC is HIGH, the DC-DC does not allow PFM Mode.
Tie SYNC to AGND if not used or in Auto-PFM Mode. This pin should not be left floating.
D3
MODE
Low-Power Auto Mode / High-Power PWM Mode select. When MODE = 1, the DC-DC is
configured for 6MHz Low-Power Auto Mode. When MODE = 0, the DC-DC is configured for 3MHz
High-Power PWM Mode. This pin should not be left floating.
A3, B3
PVIN
A2, B2
SW
A1, B1
PGND
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 point. Connect
together on PCB.
Feedback Sense pin. Connect to FB pins on PCB.
Enables switcher when HIGH; Shutdown Mode when LOW. This pin should not be left floating.
Supply voltage input to the internal MOSFET switches. Connect to input power source.
Switching node of the internal MOSFET switches. Connect to output inductor.
Power ground of the internal MOSFET switches. Follow routing notes for connections between
PGND and AGND.
© 2011 Fairchild Semiconductor Corporation
FAN5904 • Rev. 3.0.7
www.fairchildsemi.com
3
FAN5904 — Multi-Mode Buck Converter for GSM/EDGE, 3G/3.5G and 4G PAs
Pin Configuration
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
Min.
Max.
Voltage on AVIN, PVIN
-0.3
6.0
Voltage on Any Other Pin
-0.3
AVIN + 0.3
TJ
Junction Temperature
-40
+125
TSTG
Storage Temperature
-65
VIN
TL
ESD
Parameter
Lead Soldering Temperature (10 Seconds)
Electrostatic Discharge Protection Level
Human Body Model, JESD22-A114
2.0
Charged Device Model, JESD22-C101
1.0
Unit
V
°C
+150
°C
+260
°C
kV
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
VIN
Supply Voltage Range
2.7
5.5
V
VOUT
Output Voltage Range
0.35
<VIN
V
3.0
A
1.2
A
IOUT_BYP
Output Current (Bypass Mode)
IOUT_LP_MODE Output Current (Low-Power Mode)
IOUT_HP_MODE Output Current (High-Power Mode)
L
CIN
COUT
2.3
A
Inductor for Smallest PCB Footprint
470
nH
Inductor for Optimum Efficiency Performance
1.0
µH
10
µF
Input Capacitor
(1)
Output Capacitor
2 x 4.7
µF
TA
Operating Ambient Temperature Range
-40
+85
°C
TJ
Operating Junction Temperature Range
-40
+125
°C
Note:
1. A large enough input capacitor value is required for limiting the input voltage drop during GSM bursts, bypass transitions,
or during large output voltage transitions.
Dissipation Ratings
Symbol
ΘJA
Parameter
Min.
(2)
Typ.
80
Junction-to-Ambient Thermal Resistance
Max.
Unit
°C/W
Note:
2. Junction-to-ambient thermal resistance is a function of application and board layout. This data is measured with four-layer
2s2p boards in accordance to JESD51- JEDEC standard. Special attention must be paid not to exceed junction
temperature TJ(MAX) at a given ambient temperate TA.
© 2011 Fairchild Semiconductor Corporation
FAN5904 • Rev. 3.0.7
www.fairchildsemi.com
4
FAN5904 — Multi-Mode Buck Converter for GSM/EDGE, 3G/3.5G and 4G PAs
Absolute Maximum Ratings
VIN = VOUT + 0.6 V, IOUT = 200 mA, EN = VIN, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C
and VIN = 3.7 V.
Symbol
Parameter
Condition
Min.
Typ.
Max.
Unit
5.5
V
1.0
3.0
µA
2.45
2.60
V
Power Supplies
VIN
Input Voltage range
IOUT ≤ 2.3 A
ISD
Shutdown Supply Current
EN = 0 V
VUVLO
Under Voltage Lockout Threshold
VIN Rising
3.0
2.30
Hysteresis
175
mV
Logic Control
VIH
VIL
ICTRL
Logic Threshold Voltage
EN, BPEN, SYNC, MODE
Logic Control Input Bias Current
EN, BPEN, SYNC, MODE
Input HIGH Threshold
1.2
Input LOW Threshold
0.4
VIN or GND
0.01
1.00
V
µA
Analog Control
VCON_BP_EN VCON Forced Bypass Enter
VCON Voltage that Forces Bypass;
VIN = 2.70 V – 4.75 V
VCON_BP_EX VCON Forced Bypass Exit
VCON Voltage that Exits Forced;
Bypass; VIN = 2.70 V – 4.75 V
Gain
VOUT_ACC
1.6
Gain in Control Range: 0.16 V to
1.40 V
VOUT Accuracy
V
1.4
V
+50
mV
2.5
Ideal = 2.5 x VCON
-50
Bypass
RFET
ΔVOUT_BP
Bypass FET Resistance(3)
Bypass Mode Output Voltage Drop
35
mΩ
70
mV
Rising Temperature
+150
°C
Hysteresis
+20
°C
IOUT = 2 A
Over Temperature Protection
TOTP
Over-Temperature Protection
Note:
3. Bypass FET resistance does not include PFET RDSON and inductor DCR in parallel with the bypass FET in Bypass Mode.
© 2011 Fairchild Semiconductor Corporation
FAN5904 • Rev. 3.0.7
www.fairchildsemi.com
5
FAN5904 — Multi-Mode Buck Converter for GSM/EDGE, 3G/3.5G and 4G PAs
Electrical Characteristics, All Power Modes
VIN = VOUT + 0.6 V, IOUT = 200 mA, EN = VIN, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C
and VIN = 3.7 V.
Symbol
Parameter
Condition
Min.
Typ.
Max.
Unit
5.4
6.0
6.6
MHz
4.8
6.0
7.2
MHz
Oscillator / Synchronization
fSW
fSYNC
Average Oscillator Frequency
Synchronization Frequency Range
(4)
DC-DC
RDSON
PMOS On Resistance
VIN = VGS = 3.7 V
210
mΩ
NMOS On Resistance
VIN = VGS = 3.7 V
125
mΩ
ILIMp
P-Channel Current Limit
1.35
1.65
1.95
A
ILIMn
N-Channel Current Limit
1.00
1.30
1.70
A
VOUT_MIN
Minimum Output Voltage
VCON = 0.16 V
0.35
0.40
0.45
V
VOUT_MAX Maximum Output Voltage
VCON = 1.40 V
3.45
3.50
3.55
V
DC-DC Efficiency
ηPower
Power Efficiency,
Low-Power Auto Mode, VIN = 3.7 V
VOUT = 3.1 V, ILOAD = 250 mA
95
VOUT = 1.8 V, ILOAD = 250 mA
90
VOUT = 0.5 V, ILOAD = 10 mA
65
3.1 ≤ VIN ≤ 3.7
+5
%
Output Regulation
VOUT_RLine VOUT Line Regulation
mV
VOUT_RLoad VOUT Load Regulation
20 mA ≤ IOUT ≤ 800 mA
+25
mV
VBYPSLEW VOUT Slew Rate
During Bypass Enabling
0.25
V/µs
VBP_ThH
Voltage Threshold to Enter Bypass
VIN – VPMOS – VOUT
140
190
240
mV
VBP_ThL
Voltage Threshold to Exit Bypass
VIN – VOUT
340
400
440
mV
PFM Mode, VIN = 3.8 V,
IOUT < 100 mA
11
PWM Mode, VIN = 3.8 V
4
Startup Time
VIN = 3.7 V, VOUT from 0 V to
3.1 V, COUT = 2 x 4.7 µF, 10 V,
X5R
50
tDC-DC_TR
VOUT Step Response Rise Time(5)
tDC-DC_TF
VOUT Step Response Fall Time(5)
tDC-DC_CL
Maximum Allowed Time for
Consecutive Current Limit(6)
40
µs
tDCDC_CLR
Consecutive Current Limit Recovery
Time(4)
180
µs
VOUT_Ripple VOUT Ripple(4)
mV
Timing
tSS
60
µs
VOUT from 5% to 95%, ∆VOUT <
2 V (1.4 V – 3.4 V), RLOAD ≤ 7 Ω
10
µs
VOUT from 95% to 5%, ∆VOUT <
2 V (3.4 V – 1.4 V), RLOAD ≤ 7 Ω
10
µs
Notes:
4. Guaranteed by design; not tested in production.
5. Guaranteed by design; not tested in production. Voltage transient only. Maximum specified VOUT transition step is 3.1 V.
Assumes COUT = 2 x 4.7 µF.
6. Protects part under short-circuit conditions. After 40 µs nominally, operation halts and restarts after 180 µs nominally. Under
heavy capacitive loads, VCON slew rate should be reduced to avoid consecutive current limits. Under typical conditions for a
3 V change at the output, a capacitive only load of up to 40 µF is supported (assuming a step at the VCON input).
© 2011 Fairchild Semiconductor Corporation
FAN5904 • Rev. 3.0.7
www.fairchildsemi.com
6
FAN5904 — Multi-Mode Buck Converter for GSM/EDGE, 3G/3.5G and 4G PAs
Electrical Characteristics, Low-Power Auto Mode (MODE = 1)
VIN = VOUT + 0.6 V, IOUT = 200 mA, EN = VIN, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C
and VIN = 3.7 V.
Symbol
Parameter
Condition
Min.
Typ.
Max.
Unit
2.7
3.0
3.3
MHz
2.4
3.0
3.6
MHz
Oscillator / Synchronization
fSW
fSYNC
Average Oscillator Frequency
Synchronization Frequency Range
(7)
DC-DC
RDSON
PMOS On Resistance
VIN = VGS = 3.7 V
105
mΩ
NMOS On Resistance
VIN = VGS = 3.7 V
60
mΩ
ILIMp
P-Channel Current Limit
2.7
3.3
3.9
A
ILIMn
N-Channel Current Limit
1.0
1.3
1.7
A
VOUT_MIN
Minimum Output Voltage
VCON = 0.16 V
0.35
0.40
0.45
V
VOUT_MAX Maximum Output Voltage
VCON = 1.40 V
3.45
3.50
3.55
V
DC-DC Efficiency
VOUT = 3.3 V, ILOAD = 1.6 A
92
VOUT = 2.0 V, ILOAD = 0.2 A
88
VOUT_RLine VOUT Line Regulation
3.1 ≤ VIN ≤ 3.7
+5
mV
VOUT_RLoad VOUT Load Regulation
20 mA ≤ IOUT ≤ 2000 mA
+25
mV
ηPower
Power Efficiency,
High-Power Auto Mode, VIN = 3.7 V
%
Output Regulation
VBYPSLEW VOUT Slew Rate
During Bypass Enabling
0.25
V/µs
VBP_ThH
Voltage Threshold to Enter Bypass
VIN – VPMOS – VOUT
295
340
385
mV
VBP_ThL
Voltage Threshold to Exit Bypass
VIN – VOUT
550
650
750
mV
(7)
VOUT_Ripple VOUT Ripple
PWM Mode, VIN = 3.8 V
4
Startup Time
VIN = 3.7 V, VOUT from 0 V to
3.1 V, COUT = 2 x 4.7 µF, 10 V,
X5R
50
tDC-DC_TR
VOUT Step Response Rise Time(8)
tDC-DC_TF
mV
Timing
60
µs
VOUT from 5% to 95%, ∆VOUT <
1.5 V (0.5 V – 2.0 V), RLOAD ≤ 7 Ω
10
µs
VOUT Step Response Fall Time(8)
VOUT from 95% to 5%, ∆VOUT <
1.5 V (2.0 V – 0.5 V), RLOAD ≤ 7 Ω
10
µs
tDC-DC_TR
VOUT Step Response Rise Time(8)
VOUT from 5% to 95%, ∆VOUT <
3.0 V (0.4 V – 3.4 V), RLOAD ≤ 7 Ω
10
µs
tDC-DC_TF
VOUT Step Response Fall Time(8)
VOUT from 95% to 5%, ∆VOUT <
3.0 V (3.4 V – 0.4 V), RLOAD ≤ 7 Ω
12
µs
tDC-DC_CL
Maximum Allowed Time for
Consecutive Current Limits(9)
40
µs
tDCDC_CLR
Consecutive Current Limit Recovery
Time(4)
180
µs
tSS
Notes:
7. Guaranteed by design; not tested in production.
8. Guaranteed by design; not tested in production. Voltage transient only. Maximum specified VOUT transition step is 3.1 V.
Assumes COUT = 2 x 4.7 µF.
9. Protects part under short-circuit conditions. Under heavy capacitive loads, VCON slew rate may be adjusted to avoid
consecutive current limits. Under typical conditions for a 3 V change at the output, a capacitive only load of up to 40 µF is
supported (assuming a step at the VCON input).
© 2011 Fairchild Semiconductor Corporation
FAN5904 • Rev. 3.0.7
www.fairchildsemi.com
7
FAN5904 — Multi-Mode Buck Converter for GSM/EDGE, 3G/3.5G and 4G PAs
Electrical Characteristics, High-Power PWM Mode (MODE = 0)
Unless otherwise noted, VIN = EN = 3.7 V, L = 1.0 µH, COUT = 2 x 4.7 µF, and TA = +25°C.
100%
90%
90%
80%
Efficiency (%)
Efficiency (%)
100%
70%
60%
VIN = 2.7V
VIN = 3.7V
VIN = 4.2V
VIN = 5.5V
50%
40%
80%
70%
VIN = 2.7V
VIN = 3.7V
VIN = 4.2V
VIN = 5.5V
60%
50%
0
400
800 1200 1600 2000 2400
0.0
Output Current (mA)
90%
90%
80%
80%
Efficiency (%)
Efficiency (%)
100%
70%
VIN = 2.7V
VIN = 3.7V
VIN = 4.2V
VIN = 5.5V
40%
4.0
70%
60%
VIN = 2.7V
VIN = 3.7V
VIN = 4.2V
VIN = 5.5V
50%
40%
0
200
400
600
800
1000 1200
0.0
Output Current (mA)
90%
80%
80%
Efficiency (%)
100%
90%
70%
60%
VIN = 2.7V
VIN = 3.7V
VIN = 4.2V
VIN = 5.5V
40%
30%
20%
4.0
60%
50%
40%
30%
100 200 300 400 500 600 700 800
VIN = 2.7V
VIN = 3.7V
VIN = 4.2V
VIN = 5.5V
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0
Output Current (mA)
Output Voltage (V)
Figure 10. High-Power PWM Mode Efficiency vs. Output
Voltage vs. Input Voltage, fSW = 3 MHz, RPA = 5.0 Ω
Figure 9. High-Power PWM Mode Efficiency vs. Output
Current vs. Input Voltage, fSW = 3 MHz, RPA = 5.0 Ω
© 2011 Fairchild Semiconductor Corporation
FAN5904 • Rev. 3.0.7
3.0
70%
20%
0
2.0
Figure 8. High-Power PWM Mode Efficiency vs. Output
Voltage vs. Input Voltage, fSW = 3 MHz, RPA = 3.0 Ω
100%
50%
1.0
Output Voltage (V)
Figure 7. High-Power PWM Mode Efficiency vs. Output
Current vs. Input Voltage, fSW = 3 MHz, RPA = 3.0 Ω
Efficiency (%)
3.0
Figure 6. High-Power PWM Mode Efficiency vs. Output
Voltage vs. Input Voltage, fSW = 3 MHz, RPA = 1.5 Ω
100%
50%
2.0
Output Voltage (V)
Figure 5. High-Power PWM Mode Efficiency vs. Output
Current vs. Input Voltage, fSW = 3 MHz, RPA = 1.5 Ω
60%
1.0
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8
FAN5904 — Multi-Mode Buck Converter for GSM/EDGE, 3G/3.5G and 4G PAs
Typical Characteristics
Unless otherwise noted, VIN = EN = 3.7 V, L = 1.0 µH, COUT = 2 x 4.7 µF, and TA = +25°C.
90%
90%
80%
80%
Efficiency (%)
100%
Efficiency (%)
100%
70%
60%
VIN = 2.7V
VIN = 3.7V
VIN = 4.2V
VIN = 5.5V
50%
40%
0
100
200
300
400
70%
60%
VIN = 2.7V
VIN = 3.7V
VIN = 4.2V
VIN = 5.5V
50%
40%
0
500
90%
90%
80%
80%
Efficiency (%)
100%
Efficiency (%)
100%
70%
VIN = 2.7V
VIN = 3.7V
VIN = 4.2V
VIN = 5.5V
40%
4
70%
60%
VIN = 2.7V
VIN = 3.7V
VIN = 4.2V
VIN = 5.5V
50%
40%
0
100
200
300
400
0.0
Output Current (mA)
1.0
2.0
3.0
4.0
Output Voltage (V)
Figure 13. Low-Power Auto Mode Efficiency vs. Output
Current vs. Input Voltage, fSW = 6 MHz, RPA = 10.0 Ω
Shutdown Current (μA)
3
Figure 12. Low-Power Auto Mode Efficiency vs. Output
Voltage vs. Input Voltage, fSW = 6 MHz, RPA = 7.0 Ω
Figure 11. Low-Power Auto Mode Efficiency vs. Output
Current vs. Input Voltage, fSW = 6 MHz, RPA = 7.0 Ω
50%
2
Output Voltage (V)
Output Current (mA)
60%
1
Figure 14. Low-Power Auto Mode Efficiency vs. Output
Voltage vs. Input Voltage, fSW = 6 MHz, RPA = 10.0 Ω
3.25
-40°C
2.75
+25°C
2.25
+85°C
1.75
1.25
0.75
0.25
2.5
3.0
3.5
4.0
4.5
5.0
5.5
6.0
Input Voltage (V)
Figure 15. Shutdown Current vs. Input Voltage
vs. Temperature
© 2011 Fairchild Semiconductor Corporation
FAN5904 • Rev. 3.0.7
www.fairchildsemi.com
9
FAN5904 — Multi-Mode Buck Converter for GSM/EDGE, 3G/3.5G and 4G PAs
Typical Characteristics
Unless otherwise noted, VIN = EN = 3.7 V, L = 1.0 µH, COUT = 2 x 4.7 µF, and TA = +25°C.
Figure 16. Rise Times for 300 mV, 500 mV, and 2 V ΔVOUT
(VIN = 3.7 V)
Figure 17. Rise Times for 300 mV, 500 mV, and 2 V ΔVOUT
(VIN = 3.7 V)
Figure 18. Line Transient VIN = 3.7 V to 4.2 V, VOUT = 1.0 V, Figure 19. Line Transient VIN = 3.7 V to 4.2 V, VOUT = 2.5 V,
10 Ω Load, 50 µs/div.
10 Ω Load, 50 µs/div.
Figure 20. Line Transient VIN = 3.7 V to 4.2 V, VOUT = 1.0 V, Figure 21. Line Transient VIN = 3.7 V to 4.2 V, VOUT = 2.5 V,
5 Ω Load, 50 µs/div.
5 Ω Load, 50 µs/div.
© 2011 Fairchild Semiconductor Corporation
FAN5904 • Rev. 3.0.7
www.fairchildsemi.com
10
FAN5904 — Multi-Mode Buck Converter for GSM/EDGE, 3G/3.5G and 4G PAs
Typical Characteristics
Unless otherwise noted, VIN = EN = 3.7 V, L = 1.0 µH, COUT = 2 x 4.7 µF, and TA = +25°C.
Figure 22. Load Transient, 0 mA to 400 mA, VOUT = 1.0 V
in High-Power Mode
Figure 23. Load Transient, 0 mA to 400 mA, VOUT = 1.0 V
in Low-Power Mode
Figure 24. Load Transient, 0 mA to 400 mA, VOUT = 2.5 V
in High-Power Mode
Figure 25. Load Transient, 0 mA to 400 mA, VOUT = 2.5 V
in Low-Power Mode
Figure 26. Load Transient, 200 mA to 800 mA, VOUT = 1.0 V Figure 27. Load Transient, 200 mA to 800 mA, VOUT = 1.0 V
in High-Power Mode
in Low-Power Mode
© 2011 Fairchild Semiconductor Corporation
FAN5904 • Rev. 3.0.7
www.fairchildsemi.com
11
FAN5904 — Multi-Mode Buck Converter for GSM/EDGE, 3G/3.5G and 4G PAs
Typical Characteristics
Unless otherwise noted, VIN = EN = 3.7 V, L = 1.0 µH, COUT = 2 x 4.7 µF, and TA = +25°C.
Figure 28. Load Transient, 200 mA to 800 mA, VOUT = 2.5 V Figure 29. Load Transient, 200 mA to 800 mA, VOUT = 2.5 V
in High-Power Mode
in Low-Power Mode
Figure 30. Load Transient, 400 mA to 2000 mA, VOUT = 1.0 VFigure 31. Load Transient, 400 mA to 2000 mA, VOUT = 2.5 V
in High-Power Mode
in High-Power Mode
Figure 32. Switching Waveforms, PFM Mode,
ILOAD = 10 mA in Low-Power Mode
© 2011 Fairchild Semiconductor Corporation
FAN5904 • Rev. 3.0.7
Figure 33. Switching Waveforms, PWM Mode, fSW = 6 MHz,
ILOAD = 300 mA in Low-Power Mode
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12
FAN5904 — Multi-Mode Buck Converter for GSM/EDGE, 3G/3.5G and 4G PAs
Typical Characteristics
Unless otherwise noted, VIN = EN = 3.7 V, L = 1.0 µH, COUT = 2 x 4.7 µF, and TA = +25°C.
Figure 34. Switching Waveforms, PWM Mode, fSW = 3 MHz, Figure 35. Switching Waveforms, PWM Mode, fSW = 3 MHz,
ILOAD = 800 mA in High-Power Mode
ILOAD = 2000 mA in High-Power Mode
Figure 36. VOUT Rising Transition 0.5 V to 2.5 V,
VIN = 3.7 V in Low-Power Mode
Figure 37. VOUT Falling Transition 2.5 V to 0.5 V,
VIN = 3.7 V in Low-Power Mode
Figure 38. VOUT Rising Transition 0.5 V to 3.0 V, VIN = 3.7 V Figure 39. VOUT Falling Transition 3.0 V to 0.5 V, VIN = 3.7 V
in High-Power Mode
in High-Power Mode
© 2011 Fairchild Semiconductor Corporation
FAN5904 • Rev. 3.0.7
www.fairchildsemi.com
13
FAN5904 — Multi-Mode Buck Converter for GSM/EDGE, 3G/3.5G and 4G PAs
Typical Characteristics
Unless otherwise noted, VIN = EN = 3.7 V, L = 1.0 µH, COUT = 2 x 4.7 µF, and TA = +25°C.
Figure 40. VOUT Transient Response ΔVOUT = 3 V in
High-Power Mode
Figure 41. VOUT Transient Response ΔVOUT = 3 V in
Low-Power Mode
Figure 42. VOUT Transient and Bypass Response
∆VOUT > 3 V, VCON Stepped Above 1.5 V
Figure 43. VOUT Transient and Bypass Response
∆VOUT > 3 V, VCON Stepped Above 1.5 V
Figure 44. Soft-Start Transient Response from
0 mA to 100 mA in High-Power Mode
Figure 45. Soft-Start Transient Response from
0 mA to 100 mA in Low-Power Mode
© 2011 Fairchild Semiconductor Corporation
FAN5904 • Rev. 3.0.7
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14
FAN5904 — Multi-Mode Buck Converter for GSM/EDGE, 3G/3.5G and 4G PAs
Typical Characteristics
Unless otherwise noted, VIN = EN = 3.7 V, L = 1.0 µH, COUT = 2 x 4.7 µF, and TA = +25°C.
High VOUT
Low VOUT
Figure 46. Soft-Start Transient Response from
0 mA to 800 mA in High-Power Mode
Figure 47. Soft-Start Transient Response from
0 mA to 800 mA in Low-Power Mode
Figure 48. Soft-Start Transient Response from
0 mA to 2000 mA in High-Power Mode
Figure 49. Shutdown Transient Response, No Load
Figure 50. Cold-Start Transient Response from
0 mA to 100 mA in High-Power Mode
Figure 51. Cold-Start Transient Response from
0 mA to 100 mA in Low-Power Mode
© 2011 Fairchild Semiconductor Corporation
FAN5904 • Rev. 3.0.7
www.fairchildsemi.com
15
FAN5904 — Multi-Mode Buck Converter for GSM/EDGE, 3G/3.5G and 4G PAs
Typical Characteristics
Unless otherwise noted, VIN = EN = 3.7 V, L = 1.0 µH, COUT = 2 x 4.7 µF, and TA = +25°C.
Figure 52. Cold-Start Transient Response from
0 mA to 500 mA in High-Power Mode
© 2011 Fairchild Semiconductor Corporation
FAN5904 • Rev. 3.0.7
Figure 53. Cold-Start Transient Response from
0 mA to 500 mA in Low-Power Mode
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16
FAN5904 — Multi-Mode Buck Converter for GSM/EDGE, 3G/3.5G and 4G PAs
Typical Characteristics
The FAN5904 is a high-efficiency, synchronous, stepdown converter operating with current-mode control. A
wide range of load currents is supported. High-current
applications, up to a DC output of 2.3 A demanded by
GSM/EDGE applications, are allowed. Performance
degradation due to spurs is mitigated by selection of a
3 MHz or 6 MHz switching rate. Moreover, the FAN5904
offers Bypass Mode, where the output is shorted to the
battery input via a low on-state resistance bypass FET.
The output voltage VOUT is regulated to 2.5 times the input
control voltage, VCON, set by an external DAC. The
FAN5904 operates in either PWM or PFM Mode,
depending on the output voltage and load current.
In Pulse Width Modulation (PWM) Mode, regulation
begins with an on-state where a P-channel transistor is
turned on and the inductor current is ramped up until the
off-state begins. In off-state, the P-channel is switched off
and an N-channel transistor is turned on. The inductor
current decreases to maintain an average value equal to
the DC load current. The inductor current is continuously
monitored. A current sense detects when the P-channel
transistor current exceeds the current limit and the
switcher is turned back to off-state to decrease the inductor
current and prevent magnetic saturation. Similarly, the
current sense detects when the N-channel transistor current
exceeds the current limit and redirects discharging current
through the inductor back to the battery.
In Pulse Frequency Modulation (PFM) Mode, at low
load currents, the FAN5904 operates in a constant on-time
mode. During the on-state, the P-channel is turned on for
a specified on-time before switching to off-state, during
which the N-channel switch is enabled until the inductor
current decreases to 0 A. The switcher output is then put
in high-impedance state until a new regulation cycle starts.
PFM operation is allowed only in Low-Power Mode. At low
load currents, PFM achieves higher efficiencies than
PWM. To allow optimization of system performance, two
versions of the FAN5904 are available. The
FAN5904UC00X enables PFM only when VOUT is less
than approximately 1 V. The FAN5904UC01X allows PFM
to be entered at higher output voltages.
PFM Mode is only enabled for output load currents
nominally less than 100 mA. This realizes high efficiency
down to 10mA load current. This is not supported in HighPower Mode (MODE = 0) and may be disabled in LowPower Mode by tying the SYNC input HIGH.
Low-Power Auto Mode (MODE = 1)
Low-Power Auto Mode is ideal for 3G/3.5G and 4G
applications. Current sense limits are nominally 1.65 Apk
and power levels up to 29 dBm are supported.
High-Power PWM Mode (MODE = 0)
Due to the large current requirements in GSM/EDGE
applications, only PWM Mode is supported when the
FAN5904 is configured for High-Power Mode. Currentsense limits are increased to allow for large load currents
up to a maximum of approximately 3.3 A.
Bypass Mode
In Bypass Mode, the DC-DC turns into 100% duty cycle
and the bypass FET is turned on, which allows a very low
voltage dropout and up to 3.0 A load current.
Table 1. Mode Definitions
Mode
Mode Description
Conditions
MODE
SYNC
BPEN
EN
X
X
X
0
1
0
0
1
3 Forced PWM Mode Low Power DC-DC in PWM Mode only
1
1
0
1
4 PWM Mode High Power
DC-DC in PWM High-Power Mode
0
0
0
1
5 Bypass Mode
Bypass FET and PFET forced to 100% duty-cycle
X
X
1
1
1 Standby Mode
2 Auto Mode Low Power
Whole IC disabled
(10)
DC-DC in Auto Mode
Note:
10. When VOUT exceeds the bypass threshold, the bypass FET is enabled and the DC-DC goes to 100% duty cycle. When
VOUT is less than the exit threshold, the bypass FET is disabled and the DC-DC re-enters Auto Mode.
© 2011 Fairchild Semiconductor Corporation
FAN5904 • Rev. 3.0.7
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17
FAN5904 — Multi-Mode Buck Converter for GSM/EDGE, 3G/3.5G and 4G PAs
Operating Description
The output voltage of the FAN5904 is determined by VCON
provided by an external DAC or voltage reference:
VOUT = 2.5 ×VCON
(1)
Figure 55. Enabling Bypass Transistor Circuit
The bypass FET is turned on progressively using a slew rate
controller to limit the inrush current since Bypass Mode
effectively shorts the input supply bus to a capacitive load.
The resulting inrush current is expressed as a function of the
specified slew rate as follows:
IINRUSH ≈ COUT
Figure 54. Output Voltage vs. Control Voltage
ΔVOUT
= COUT • VBP_SLEW
Δt
(2)
PFM Lockout Mode and Synchronization
The FAN5904 is able to provide a regulated VOUT only if VCON
falls within the typical range from 0.16 V to 1.40 V. This allows
VOUT to be adjusted between 0.4 V and 3.5 V. If VCON is less
than 0.16 V, VOUT is clamped to 0.40 V.The part enters
Bypass Mode for VCON > 1.50 V. In Low-Power Mode (MODE
= 1), the FAN5904 automatically switches between PFM,
PWM, and Bypass Modes. In High-Power Mode (MODE = 0),
the FAN5904 automatically switches between PWM and
Bypass Modes and PFM operation is not available.
It may be desirable to prevent the DC-DC converter from
operating in PFM Mode. For example, the low PFM
switching frequency may interfere with audio circuitry and
using PWM may eliminate the interference. When configured
for Low-Power Mode (MODE = 1) a logic 1 on the SYNC pin
forces the IC to avoid PFM Mode. Logic 0 allows the IC to
automatically switch to PFM Mode during light loads.
When VOUT approaches the battery voltage, the DC-DC
operates in a constant off-time mode and the frequency is
adjusted to achieve high duty cycle. The system operates in
this regulated mode until the bypass condition is satisfied.
In Low-Power or High-Power Modes, toggling the SYNC pin
forces the converter to synchronize its switching frequency
to the frequency on the SYNC pin (fSYNC). The signal must be
within the oscillator synchronization frequency range and
meet the threshold voltage requirements.
Bypass Mode
Dynamic Output Voltage Transitions
As VOUT and the battery voltage converge, the DC-DC
begins to operate in constant off-time mode until eventually
the DC-DC transitions to 100% duty cycle and the low RDSON
bypass FET is turned on. The battery voltage that results in
100% duty cycle operation depends on the output voltage,
the voltage drop across the DC-DC converter, and the DC
voltage drop across the inductor. In other words, the duty
cycle is set by the ratio of the voltages across the inductor.
FAN5904 has a complex voltage transition controller that
realizes 10µs transition times with a large output capacitor
and output voltage ranges.
The transition controller manages five transitions:





In many RF applications, it is undesirable for the DC-DC to
reach 100% duty cycle since this would result in excessive
output ripple. To minimize ripple, the FAN5904 implements a
dynamic bypass threshold based on the voltage difference
between the battery voltage (sensed through the AVIN pin),
the voltage drop across the DC-DC PMOS device, and the
internally generated reference voltage VREF, as described in
Figure 55. The Bypass Mode enter and exit thresholds are
higher in High-Power Mode due to the higher load current
capability. Bypass Mode is also entered when VCON exceeds
1.5 V and exited when VCON is less than 1.4 V.
© 2011 Fairchild Semiconductor Corporation
FAN5904 • Rev. 3.0.7
ΔVOUT positive step
ΔVOUT negative step
ΔVOUT transition from or to Bypass Mode
ΔVOUT transition at startup
ΔVOUT transition after BPEN
In all cases, it is recommended that sharp VCON transitions
be applied, letting the transition controller optimize the output
voltage slew rate.
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18
FAN5904 — Multi-Mode Buck Converter for GSM/EDGE, 3G/3.5G and 4G PAs
DC Output Voltage
VOUT Transition after BPEN
When BPEN goes HIGH, the controller dismisses the
internal bypass flags and sensors and enables Bypass
Mode. However, the transition is managed with the same
current limits and slew rate used during regular transitions.
ΔVOUT Negative Step
After a VCON negative step, the FAN5904 enters a current
limit mode where VOUT is reduced with a constant slew rate
dictated by the output capacitor and the current limit ILIMn.
Thermal Protection
VOUT Transition to or from Bypass Mode
The transition to or from Bypass Mode requires that the
bypass conditions be met. The FAN5904 performs detection
of the bypass conditions 2 µs after VCON transition and
enables the required charging / discharging circuit to realize
a transition time of 20 µs.
When the junction temperature exceeds the maximum
specified junction temperature, the FAN5904 enters PowerDown Mode (except the thermal detection circuit).
VOUT Transition at Startup
Application Information
Figure 56 illustrates an application of the FAN5904 in a
GSM/EDGE/WCDMA
transmitter
configuration.
The
FAN5904 is ideal for driving multiple GSM/EDGE and
3G/3.5G and 4G PAs. Figure 57 presents a timing diagram
designed to meet GSM specifications. The FAN5904 is
designed to support voltage transients of 10 µs when
configured for GSM/EDGE applications (MODE = 0) and
driving a load capacitance of approximately 10 µF. Figure 58
shows a timing diagram for WCDMA applications.
Figure 56. Typical Application Diagram with GSM/EDGE/WCDMA Transmitters
© 2011 Fairchild Semiconductor Corporation
FAN5904 • Rev. 3.0.7
www.fairchildsemi.com
19
FAN5904 — Multi-Mode Buck Converter for GSM/EDGE, 3G/3.5G and 4G PAs
At startup, after EN rising edge is detected, the system
requires 25 µs to allow all internal voltage references and
amplifiers to start before enabling the DC-DC function.
ΔVOUT Positive Step
After a VCON positive step, the FAN5904 goes into a current
limit mode, where VOUT ramps with a constant slew rate
dictated by the output capacitor and the current limit ILIMp
Figure 58. Timing Diagram for WCDMA Transmitters
Application Information
Inductor Selection
Capacitor Selection
The FAN5904 operates at 6 MHz switching frequency in
Low-Power Mode and 3 MHz in High-Power Mode and, as
such, 470 nH or 1.0 µH inductors can be used, respectively.
For applications requiring the smallest possible PCB area,
use a 470 nH 2016 inductor; or a 1.0 µH 3030 inductor for
optimum efficiency performance.
The minimum required output capacitor COUT should be two
(2) 4.7 µF, 10 V, X5R with an ESR of 10 mΩ or lower, and
an ESL of 0.3 nH or lower placed in parallel after inductor
L1. Larger case sizes result in increased loop parasitic
inductance and higher noise. One of the 4.7 µF capacitors
should be used as a decoupling capacitor at the GSM/EDGE
PA VCC pin.
Table 2. Recommended Inductors
Inductor
A 0.1 µF capacitor may be added in parallel with COUT to
reduce the capacitor’s parasitic inductance.
Description
470 nH, ±30%, 2.3 A, 2016 (metric)
TDK: VLS201610MT-R47N
L
Table 3. Recommended Capacitor Values
470 nH, ±30%, 2.8 A, 2520 (metric)
TDK: VLS252010T-R47N
Capacitor
470 nH, ±20%, 2.3 A, 2520 (metric)
Samsung: CIG22HR47MNE
COUT
CIN
C for VCON
470 nH, ±20%, 1.8 A, 2520 (metric)
Taiyo-Yuden: CKP2520R47M
Description
10 µF, ±20%, X5R, 10 V
(2) 4.7 µF, ±20%, X5R, 6.3 V
470 pF, ±20%, X5R, 25 V
1.0 µH, ±20%, 2.4 A, 3030 (metric)
Coilcraft: XFL3010-102ME
© 2011 Fairchild Semiconductor Corporation
FAN5904 • Rev. 3.0.7
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20
FAN5904 — Multi-Mode Buck Converter for GSM/EDGE, 3G/3.5G and 4G PAs
Figure 57. Timing Diagram for GSM/EDGE Transmitters
Assembly
VCON is the analog control pin of the DC-DC and should be
connected to an external Digital-to-Analog Converter (DAC).
It is recommended to add up to 470 pF decoupling
capacitance between VCON and AGND to filter DAC noise.
This capacitor also helps protect the DAC from the DC-DC
high-frequency switching noise inherently coupled through
the VCON pin. The value of the capacitor must be selected
according to the DAC performance since it could limit the
DAC output voltage slew rate. 470 pF is typically used.

Use lead-free solder reflow temperature profile.

Use metal-filled or solder-filled vias, if available.

Poor soldering can cause low DC-DC conversion
efficiency. If the efficiency is low, X-ray the solder
connections to verify their integrity.

PVIN and PGND must be routed with the widest and
shortest traces possible. It is acceptable for the traces
connecting the inductor to be long rather than having
long PVIN or PGND traces.

Ensure that the routing loop, PVIN – PGND – VOUT is
as short as possible.

Place PGND on the top layer and connect it to the
AGND ground plane next to Cout using several vias.

The SW node is a source of electrical switching noise.
Do not route it near the VCON pin.

Two small vias are used to connect the SW node to the
inductor L1. Use solder-filled vias, if available.

The connection from COUT to FB should be wide to
minimize the Bypass Mode voltage drop and the series
inductance. Even if the current in Bypass Mode is small,
keep this trace short and at least 5 mm wide.

The AGND ground plane should not be broken into
pieces. Ground currents must have a direct, wide path
from input to output.

Each capacitor should have at least two dedicated
ground vias. Place vias within 0.1 mm of the capacitors.
Any noise on the VCON input is transferred to VOUT with a gain
of two and a half (2.5). If the DAC output is noisy, a series
resistor may be inserted between the DAC output and the
capacitor to form an RC filter.
Follow these guidelines:

Use a low noise source or a driver with good PSRR to
generate VCON.

The VCON driver must be referenced to AGND.

VCON routing must be protected against PVIN, SW, and
PGND signals, as well as other noisy signals. Use
AGND shielding for better isolation.

Be sure the DAC output can drive the capacitor on
VCON. It may be necessary to insert a low-value
resistor to ensure DAC stability while not slowing VCON
fast transition times.
No Floating Inputs
The FAN5904 does not have internal pull-down resistors on
its inputs. Therefore, unused inputs should not be left
floating and should be pulled HIGH or LOW.
PCB Layout and Component Placement

The key point in the placement is the power ground
PGND connection shared between the FAN5904, C1,
and C2. This minimizes the parasitic inductance of the
switching loop paths.

Place the inductor away from the feedback pins to
prevent unpredictable loop behavior.

Ensure the traces are wide enough to handle the
maximum current value, especially in Bypass mode.

Ensure the vias are able to handle the current density.
Use filled vias if available.

Refer to Fairchild’s application note: AN9726 — The
Importance of PCB Design for FAN5903 and FAN5904.
Figure 59. Example PCB Layout of FAN5904
© 2011 Fairchild Semiconductor Corporation
FAN5904 • Rev. 3.0.7
www.fairchildsemi.com
21
FAN5904 — Multi-Mode Buck Converter for GSM/EDGE, 3G/3.5G and 4G PAs
Filter VCON
0.03 C
2X
E
F
A
B
0.40
(Ø0.20)
Cu Pad
A1
BALL A1
INDEX AREA
D
0.40
(Ø0.30) Solder
Mask Opening
0.03 C
2X
RECOMMENDED LAND PATTERN
(NSMD PAD TYPE)
TOP VIEW
0.06 C
0.625
0.547
0.05 C
C
SEATING
PLANE
0.378±0.018
0.208±0.021
E
SIDE VIEWS
D
NOTES:
A. NO JEDEC REGISTRATION APPLIES.
0.005
B. DIMENSIONS ARE IN MILLIMETERS.
C A B
Ø0.260±0.02
16X
0.40
D
C
B
0.40
C. DIMENSIONS AND TOLERANCE
PER ASME Y14.5M, 1994.
D. DATUM C IS DEFINED BY THE SPHERICAL
CROWNS OF THE BALLS.
(Y) ±0.018
A
E. PACKAGE NOMINAL HEIGHT IS 586 MICRONS
±39 MICRONS (547-625 MICRONS).
F
1 2 3 4
(X) ±0.018
F. FOR DIMENSIONS D, E, X, AND Y SEE
PRODUCT DATASHEET.
BOTTOM VIEW
G. DRAWING FILNAME: MKT-UC016AArev2.
Product
D
E
X
Y
Unit
FAN5904UC00X
1.710 ±0.030
1.710 ±0.030
0.255
0.255
mm
FAN5904UC01X
1.710 ±0.030
1.710 ±0.030
0.255
0.255
mm
Figure 60. 1.71x1.71 mm Square, 16 Bumps, 0.4 mm Pitch, 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/
© 2011 Fairchild Semiconductor Corporation
FAN5904 • Rev. 3.0.7
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22
FAN5904 — Multi-Mode Buck Converter for GSM/EDGE, 3G/3.5G and 4G PAs
Physical Dimensions
FAN5904 — Multi-Mode Buck Converter for GSM/EDGE, 3G/3.5G and 4G PAs
© 2011 Fairchild Semiconductor Corporation
FAN5904 • Rev. 3.0.7
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23