FAN5358 — 2MHz, 500mA, SC70 Synchronous Buck Regulator
September 2010
FAN5358
2MHz, 500mA, SC70 Synchronous Buck Regulator
Features
2MHz Nominal-Frequency Operation
25µA Typical Quiescent Current
500mA Output Current Capability
2.7V to 5.5V Input Voltage Range
1.0 to 1.8V Fixed Output Voltages
Low Ripple, Light-Load PFM Mode
Internal Soft-Start
Input Under-Voltage Lockout (UVLO)
Thermal Shutdown and Overload Protection
6-lead 2 x 2.2mm SC70
Description
The FAN5358 is a step-down switching voltage regulator that
delivers a fixed output from an input voltage supply of 2.7V to
5.5V. Using a proprietary architecture with synchronous
rectification, the device is capable of delivering 500mA and
maintaining a very high efficiency of over 80% at load currents
as low as 1mA. The regulator operates at a nominal frequency
of 2MHz, which reduces the value of the external components
to as low as 2.2μH for the output inductor and 4.7µF for the
output capacitor.
At moderate and light loads, pulse frequency modulation is
used to operate the device in power-save mode with a typical
quiescent current of 25µA. Even with such a low quiescent
current, the part exhibits excellent transient response during
large load swings. In shutdown mode, the supply current
drops below 1µA, reducing power consumption.
FAN5358 is available in a 6-lead SC70 package.
Applications
Cell Phones, Smart Phones
3G, 4G, WiFi , WiMAX™, and WiBro Data Cards
Netbooks , Ultra-Mobile PCs
®
®
®
Typical Application
L1
Table 1. External Components for Figure 1
SW
GND
VOUT
1
2
3
6
5
4
VIN
GND
EN
C
IN
U1
FAN5358
f
SW
2MHz
L1
2.2μH
C
IN
2.2μF
C
OUT
4.7μF
U1
C
OUT
Figure 1. FAN5358 Typical Application
Trademarks are the property of their respective owners.
© 2009 Fairchild Semiconductor Corporation
FAN5358 • Rev. 1.0.2
www.fairchildsemi.com
FAN5358 — 2MHz, 500mA, SC70 Synchronous Buck Regulator
Ordering Information
Part Number
FAN5358S710X
FAN5358S712X
FAN5358S713X
FAN5358S718X
2MHz
Switching
Frequency
Output Voltage
1.0V
1.2V
1.3V
1.8V
(1)
Temperature
Range
Package
Packing
Method
–40 to +85°C
SC70-6
Tape and Reel
Note:
1. Other voltage options are available on request. Contact a Fairchild representative.
Pin Configuration
SW
GND
VOUT
1
2
3
6
5
4
VIN
GND
EN
Figure 2. Pin Assignments (Top View)
Pin Definitions
Pin #
1
2, 5
3
4
6
Name
SW
GND
VOUT
EN
VIN
Switching Node.
Connect to output inductor.
Description
Ground.
Power and IC ground. All signals are referenced to this pin.
V
OUT
/ Feedback.
Connect to output voltage.
Enable.
The device is in shutdown mode when the 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 and C
IN
.
© 2009 Fairchild Semiconductor Corporation
FAN5358 • Rev. 1.0.2
www.fairchildsemi.com
2
FAN5358 — 2MHz, 500mA, SC70 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
T
J
T
STG
T
L
ESD
Parameter
Input Voltage with Respect to GND
Voltage on Any Other Pin with Respect to GND
Junction Temperature
Storage Temperature
Lead Temperature (Soldering 10 Seconds)
Human Body Model,
JESD22-A114
Charged Device Model,
JESD22-C101
Min.
-0.3
-0.3
-40
-65
Max.
6.0
V
IN
+0.3V
+150
+150
+260
(2)
Units
V
V
°C
°C
°C
2
kV
1
Electrostatic Discharge Protection Level
Note:
2. Lesser of 6.0V 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
(3)
Parameter
Min.
2.7
0
Typ.
Max.
5.5
500
Units
V
mA
µH
µF
µF
2.2
2.2
4.7
–40
–40
+85
+125
Operating Ambient Temperature
Operating Junction Temperature
°C
°C
Thermal Properties
Symbol
Θ
JA
Parameter
Junction-to-Ambient Thermal Resistance
(4)
Min.
Typ.
285
Max.
Units
°C/W
Notes:
3. Refer to Operation Description section for guidance on maximum C
OUT
capabilities.
4. 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 T
J(max)
at a given ambient temperate T
A
.
© 2009 Fairchild Semiconductor Corporation
FAN5358 • Rev. 1.0.2
www.fairchildsemi.com
3
FAN5358 — 2MHz, 500mA, SC70 Synchronous Buck Regulator
Electrical Characteristics
Minimum and maximum values are at V
IN
= 2.7V to 5.5V, T
A
= -40°C to +85°C, circuit of Figure 1 unless otherwise noted.
Typical values are at T
A
= 25°C, V
IN
=3.6V.
Symbol
Power Supplies
I
Q
I
(SD)
V
UVLO
V
UVHYST
V
(ENH)
V
(ENL)
I
(EN)
Oscillator
f
OSC
Regulation
Parameter
Conditions
Min.
Typ.
Max.
Units
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
Switching Frequency
1.0V
No Load, EN=V
IN
EN = GND
Rising V
IN
1.2
25
0.05
2.4
225
48
1.00
2.6
µA
µA
V
mV
V
0.4
EN = V
IN
or GND
In PWM Mode
I
LOAD
= 0 to 500mA
I
LOAD
= 0 to 500mA
I
LOAD
= 0 to 500mA
I
LOAD
= 0 to 500mA
From EN Rising Edge
V
IN
= V
GS
= 3.6V
V
IN
= V
GS
= 3.6V
Open-Loop
(1)
V
µA
MHz
0.01
2
-4.5
-4.5
-4.5
-4.0
70
750
650
750
850
150
20
1.00
+4.5
+4.5
+4.5
+4.0
µs
mΩ
mΩ
1150
mA
°C
°C
%
V
O
Output Voltage
Accuracy
Soft-Start
1.2V
1.3V
1.8V
t
SS
Output Driver
R
DS(on)
I
LIM
T
TSD
T
HYS
PMOS On Resistance
NMOS On Resistance
PMOS Peak Current Limit
Thermal Shutdown
Thermal Shutdown Hysteresis
Note:
5. The Electrical Characteristics table reflects open-loop data.
Refer to Operation Description and Typical Characteristic for
closed-loop data.
Block Diagram
VIN
Q1
EN
REF
U1
C
IN
VOUT
RAMP
GEN
LOGIC
&
GATE
DRIVE
SW
Q2
L1
VOUT
C
OUT
GND
GND
Figure 3. IC Block Diagram
© 2009 Fairchild Semiconductor Corporation
FAN5358 • Rev. 1.0.2
www.fairchildsemi.com
4
FAN5358 — 2MHz, 500mA, SC70 Synchronous Buck Regulator
Typical Characteristics
Unless otherwise noted, V
IN
= V
EN
= 3.6V, V
OUT
= 1.8V, and T
A
= 25°C.
95
90
100
V
IN
=3.6V
90
Efficiency (%)
80
75
70
65
60
0.001
2.7V
IN
3.6V
IN
4.2V
IN
0.01
0.1
1
Efficiency (%)
85
80
70
-40°C
25°C
85°C
0.01
0.1
1
60
0.001
Load Current (A)
Figure 4. Efficiency vs. Load Current and Input Supply
1.815
Load Current (A)
Figure 5. Efficiency vs. Load Current and Temperature
20
Output Voltage (V)
1.810
15
1.800
1.795
1.790
1.785
1.780
0
2.7V
IN
3.6V
IN
4.2V
IN
5.5V
IN
0.1
0.2
0.3
0.4
0.5
0.6
V
OUT
(mV
pp
)
1.805
10
5
2.7V
IN
3.6V
IN
5.5V
IN
1
10
100
1000
0
Load Current (A)
Figure 6. Voltage Regulation
3.0
2.5
2.0
1.5
1.0
0.5
0
2.7V
IN
3.6V
IN
5.5V
IN
0
0.1
0.2
0.3
0.4
0.5
0.6
Load Current (mA)
Figure 7. Peak-to-Peak Output Voltage Ripple
180
Load Current (mA)
Frequency (MHz)
160
140
120
100
80
2.7
3.2
Always PWM
PFM Border
PWM Border
The switching mode
changes at these borders
Always PFM
3.7
4.2
4.7
5.2
Load Current (A)
Figure 8. Switching Frequency vs. Load Current
© 2009 Fairchild Semiconductor Corporation
FAN5358 • Rev. 1.0.2
Input Voltage (V)
Figure 9. PFM / PWM Boundaries
www.fairchildsemi.com
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