FAN5361 — 6MHz, 600mA TinyBuck™ Synchronous Buck Regulator
September 2008
FAN5361
6MHz, 600mA TinyBuck™ Synchronous Buck Regulator
Features
6MHz Fixed-Frequency Operation
35µA Typical Quiescent Current
Best-in-Class Load Transient
600mA Output Current Capability
2.3V to 5.5V Input Voltage Range
1.0 to 1.82V Fixed Output Voltage
Low Ripple Light-Load PFM Mode
Forced PWM and External Clock Synchronization
Internal Soft-Start
Input Under-Voltage Lockout (UVLO)
Thermal Shutdown and Overload Protection
6-bump WLCSP, 0.4mm Pitch
6-pin 2 x 2mm UMLP
Description
The FAN5361 is a 600mA, step-down, switching voltage
regulator that delivers a fixed output from an input voltage
supply of 2.3V to 5.5V. Using a proprietary architecture with
synchronous rectification, the FAN5361 is capable of
delivering a peak efficiency of 92%, while maintaining
efficiency over 80% at load currents as low as 1mA.
The regulator operates at a nominal fixed frequency of 6MHz,
which reduces the value of the external components to 470nH
for the output inductor and 4.7µF for the output capacitor. The
PWM modulator can be synchronized to an external frequency
source.
At moderate and light loads, pulse frequency modulation is
used to operate the device in power-save mode with a typical
quiescent current of 35µA. Even with such a low quiescent
current, the part exhibits excellent transient response during
large load swings. At higher loads, the system automatically
switches to fixed-frequency control, operating at 6MHz. In
shutdown mode, the supply current drops below 1µA,
reducing power consumption. For applications that require
minimum ripple or fixed frequency, PFM mode can be
disabled using the MODE pin.
The FAN5361 is available in 6-bump, 0.4mm pitch, Wafer-
Level Chip-Scale Package (WLCSP) and a 6-lead 2 x 2mm
ultra-thin MLP package.
Applications
Cell Phones
Portable Media Players
WLAN, 3G, and 4G Data Cards
Typical Applications
MODE
L1
470nH
FB
4.7 F
C
OUT
Figure 1. Typical Applications
SW
A1
B1
C1
A2
B2
C2
VIN
EN
GND
C
IN
2.2 F
© 2008 Fairchild Semiconductor Corporation
FAN5361 • Rev. 1.0.0
www.fairchildsemi.com
FAN5361 — 6MHz, 600mA TinyBuck™ Synchronous Buck Regulator
Ordering Information
Part Number
FAN5361UC10X
FAN5361UC12X
FAN5361UC13X
FAN5361UC15X
FAN5361UC18X
(2)
(2)
(2)
(2)
Output
(1)
Voltage
1.0V
1.2V
1.3V
1.5V
1.8V
1.82V
(2)
(2)
(2)
(2)
(2)
Package
Eco Status Temperature Range
Packing
WLCSP-6 0.4mm Pitch
Green
–40 to +85°C
Tape and Reel
FAN5361UC182X
FAN5361UMP10X
FAN5361UMP12X
FAN5361UMP13X
FAN5361UMP15X
FAN5361UMP18X
1.0V
1.2V
1.3V
1.5V
1.8V
6 Lead UMLP 2 x 2mm
RoHS
–40 to +85°C
Tape and Reel
For Fairchild’s definition of “green” Eco Status, please visit:
http://www.fairchildsemi.com/company/green/rohs_green.html.
Notes:
1. Other voltage options available on request. Contact a Fairchild representative.
2. Preliminary release.
Pin Configuration
MODE
SW
FB
A1
B1
C1
A2
B2
C2
VIN
EN
GND
VIN
EN
GND
A2
B2
C2
A1
B1
C1
MODE
SW
FB
Figure 2. WLCSP, Bumps Facing Down
Figure 3. WLCSP, Bumps Facing Up
Figure 4. UMLP, Leads Facing Down
Pin Definitions
Pin #
WLCSP MLP
A1
B1
C1
C2
B2
A2
3
2
1
6
5
4
Name Description
MODE.
Logic 1 on this pin forces the IC to stay in PWM mode. A logic 0 allows the IC to automatically
MODE switch to PFM during light loads. The regulator also synchronizes its switching frequency to four times
the frequency provided on this pin. Do not leave this pin floating.
SW
FB
GND
EN
VIN
Switching Node.
Connect to output inductor.
Feedback / VOUT.
Connect to output voltage.
Ground.
Power and IC ground. All signals are referenced to this pin.
Enable.
The device is in shutdown mode when voltage to this pin is <0.4V and enabled when >1.2V.
Do not leave this pin floating.
Input Voltage.
Connect to input power source.
© 2008 Fairchild Semiconductor Corporation
FAN5361 • Rev. 1.0.0
www.fairchildsemi.com
2
FAN5361 — 6MHz, 600mA TinyBuck™ Synchronous Buck Regulator
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
V
IN
V
SW
V
CTRL
Parameter
Input Voltage
Voltage on SW Pin
EN and MODE Pin Voltage
Other Pins
ESD
T
J
T
STG
T
L
Electrostatic Discharge
Protection Level
Junction Temperature
Storage Temperature
Lead Soldering Temperature, 10 Seconds
Human Body Model per JESD22-A114
Charged Device Model per JESD22-C101
–40
–65
Min.
–0.3
–0.3
–0.3
–0.3
4
1.5
+150
+150
+260
Max.
7.0
V
IN
+ 0.3
V
IN
+ 0.3
V
IN
+ 0.3
(3)
(3)
(3)
Units
V
V
V
V
kV
kV
°C
°C
°C
Note:
3. Lesser of 7V or V
IN
+0.3V.
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
V
CC
I
OUT
L
C
IN
C
OUT
T
A
T
J
Supply Voltage Range
Output Current
Inductor
Input Capacitor
Output Capacitor
Parameter
Min.
2.3
0
Typ.
Max.
5.5
600
Units
V
mA
µH
µF
µF
0.47
2.2
4.7
–40
–40
+85
+125
Operating Ambient Temperature
Operating Junction Temperature
°C
°C
Thermal Properties
Junction-to-ambient thermal resistance is a function of application and board layout. This data is measured with four-layer 1s2p
boards in accordance to JEDEC standard JESD51. Special attention must be paid not to exceed junction temperature T
J(max)
at a
given ambient temperate T
A
.
Symbol Parameter
θ
JA
Junction-to-Ambient Thermal Resistance
WLCSP
MLP
Typical
150
49
Units
°C/W
°C/W
© 2008 Fairchild Semiconductor Corporation
FAN5361 • Rev. 1.0.0
www.fairchildsemi.com
3
FAN5361 — 6MHz, 600mA TinyBuck™ Synchronous Buck Regulator
Electrical Characteristics
Minimum and maximum values are at V
IN
= V
EN
= 2.3V to 5.5V, AUTO Mode, T
A
= -40°C to +85°C; circuit of Figure 1, unless
otherwise noted. Typical values are at T
A
= 25°C, V
IN
= V
EN
= 3.6V.
Symbol
Parameter
Conditions
No load, Not Switching
PWM Mode
V
IN
= 3.6V, EN = GND
Rising V
IN
Min.
Typ.
35
6
0.05
2.15
150
Max.
55
1.00
2.25
Units
µA
mA
µA
V
mV
V
Power Supplies
I
Q
I
(SD)
V
UVLO
V
UVHYST
V
(ENH)
V
(ENL)
I
(EN)
V
(MH)
V
(ML)
I
(M)
f
SW
f
SYNC
Regulation
1.82V
1.80V
1.50V
1.30V
1.20V
1.00V
t
SS
Soft-Start
PMOS On Resistance
NMOS On Resistance
PMOS Peak Current Limit
Thermal Shutdown
Thermal Shutdown Hysteresis
I
LOAD
= 0 to 600mA
PWM Mode
I
LOAD
= 0 to 600mA
PWM Mode
I
LOAD
= 0 to 600mA
PWM Mode
I
LOAD
= 0 to 600mA
PWM Mode
I
LOAD
= 0 to 600mA
PWM Mode
I
LOAD
= 0 to 600mA
PWM Mode
From EN Rising Edge
V
IN
= V
GS
= 3.6V
V
IN
= V
GS
= 3.6V
Open-Loop
CCM Only
900
1.784
1.784
1.764
1.764
1.470
1.470
1.274
1.274
1.174
1.174
0.974
0.974
1.820
1.820
1.800
1.800
1.500
1.500
1.300
1.300
1.200
1.200
1.000
1.000
150
350
225
1000
150
15
1250
1.875
1.856
1.854
1.836
1.545
1.530
1.339
1.326
1.239
1.226
1.039
1.026
300
V
V
V
V
V
V
V
V
V
V
V
V
µs
mΩ
mΩ
mA
°C
°C
Quiescent Current
Shutdown Supply Current
Under-Voltage Lockout Threshold
Under-Voltage Lockout hysteresis
Enable HIGH-Level Input Voltage
Enable LOW-Level Input Voltage
Enable Input Leakage Current
MODE HIGH-Level Input Voltage
MODE LOW-Level Input Voltage
MODE Input Leakage Current
Switching Frequency
MODE Synchronization Range
(4)
1.2
0.4
EN to V
IN
or GND
1.2
0.4
MODE to V
IN
or GND
V
IN
= 3.6V, T
A
= 25°C
Squarewave at MODE Input
5.4
1.3
0.01
6.0
1.5
1.00
6.6
1.7
0.01
1.00
V
µA
V
V
µA
MHz
MHz
Switching and Synchronization
V
O
Output Voltage
Accuracy
Output Driver
R
DS(on)
I
LIM
T
TSD
T
HYS
Notes:
4. Limited by the effect of t
OFF
minimum
(see Figure 13 in Typical Performance Characteristics).
© 2008 Fairchild Semiconductor Corporation
FAN5361 • Rev. 1.0.0
www.fairchildsemi.com
4
FAN5361 — 6MHz, 600mA TinyBuck™ Synchronous Buck Regulator
Typical Performance Characteristics
Unless otherwise noted, V
IN
= V
EN
= 3.6V, V
MODE
= 0V, V
OUT
= 1.82V, T
A
= 25°C.
100%
95%
90%
85%
100%
95%
90%
85%
Efficiency
75%
70%
65%
60%
55%
50%
1
10
100
Auto 2.3VIN
Auto 2.7VIN
Auto 3.6VIN
Auto 4.2VIN
Efficiency
80%
80%
75%
70%
65%
60%
55%
50%
-30C
85C
25C
1000
1
10
100
1000
I
LOAD
Output Current (mA)
I
LOAD
Output Current (mA)
Figure 5. Efficiency vs. Load Current vs. Input Supply Figure 6. Efficiency vs. Load Current vs. Temperature
100%
95%
90%
85%
100%
95%
90%
85%
Efficiency
80%
75%
70%
65%
60%
55%
50%
1
10
100
1000
VIN=2.3V
VIN=2.7V
VIN=3.6V
VIN=4.2V
V
OUT
= 1.2 V
Efficiency
80%
75%
70%
65%
60%
55%
50%
1
10
100
1000
Auto PFM/PWM
Forced PWM
I
LOAD
Output Current (mA)
I
LOAD
Output Current (mA)
Figure 7. Efficiency vs. Load Current vs. Input Supply
1.82
Figure 8. Efficiency, Auto PWM/PFM vs. Forced PWM
1.215
VIN=2.3V
1.210
1.81
VIN=2.7V
VIN=3.6V
Output Voltage (V)
1.80
V
OUT
(V)
1.205
VIN=4.2V
VIN=2.3V
VIN=2.7V
1.79
1.200
VIN=3.6V
VIN=4.2V
1.78
0
100
200
300
400
500
600
1.195
1.190
0.0
0.1
0.2
0.3
0.4
0.5
0.6
Load Current (mA)
I
LOAD
Output Current (A)
Figure 9. Load Regulation vs. Input Supply
Figure 10. 1.2V
OUT
Load Regulation vs. Input Supply
© 2008 Fairchild Semiconductor Corporation
FAN5361 • Rev. 1.0.0
www.fairchildsemi.com
5
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