FAN5358S713X [FAIRCHILD]
2MHz, 500mA, SC70 Synchronous Buck Regulator; 为2MHz ， 500毫安， SC70同步降压稳压器
| 型号： | FAN5358S713X |
| 厂家： | 
FAIRCHILD SEMICONDUCTOR |
| 描述： | 2MHz, 500mA, SC70 Synchronous Buck Regulator |
| 文件： | 总13页 (文件大小：626K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
September 2009
FAN5358
2MHz, 500mA, SC70 Synchronous Buck Regulator
Features
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.
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
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.
Input Under-Voltage Lockout (UVLO)
Thermal Shutdown and Overload Protection
6-lead 2 x 2.2mm SC70
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
Table 1. External Components for Figure 1
L1
SW
VIN
GND
EN
1
6
5
4
U1
fSW
L1
CIN
COUT
CIN
FAN5358
2MHz
2.2μH
2.2μF
4.7μF
GND
2
U1
VOUT
3
COUT
Figure 1. FAN5358 Typical Application
Wi-Fi® is a registered trademark of Wi-Fi Alliance Corporation.
WiMax™ is a trademark of WIMAX Forum Corporation.
WiBro® is a registered trademark of Telecommunications Technology Association.
Netbooks® is a registered trademark of Netbooks, Inc.
© 2009 Fairchild Semiconductor Corporation
FAN5358 • Rev. 1.0.1
www.fairchildsemi.com
Ordering Information
Switching
Part Number
Temperature
Range
Packing
Method
Output Voltage(1)
Package
Eco Status
Frequency
FAN5358S710X
1.0V
1.2V
1.3V
1.8V
FAN5358S712X
2MHz
–40 to +85°C
SC70-6
Green
Tape and Reel
FAN5358S713X
FAN5358S718X
For Fairchild’s definition of Eco Status, please visit: http://www.fairchildsemi.com/company/green/rohs_green.html.
Note:
1. Other voltage options are available on request. Contact a Fairchild representative.
Pin Configuration
SW
GND
1
2
3
6
5
4
VIN
GND
EN
VOUT
Figure 2. Pin Assignments (Top View)
Pin Definitions
Pin # Name
Description
Switching Node. Connect to output inductor.
Ground. Power and IC ground. All signals are referenced to this pin.
OUT / Feedback. Connect to output voltage.
1
2, 5
3
SW
GND
VOUT
V
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.
4
6
EN
Input Voltage. Connect to input power source and CIN.
VIN
© 2009 Fairchild Semiconductor Corporation
FAN5358 • Rev. 1.0.1
www.fairchildsemi.com
2
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
Parameter
Input Voltage with Respect to GND
Min.
Max.
Units
-0.3
-0.3
-40
-65
6.0
VIN +0.3V(2)
+150
V
VIN
Voltage on Any Other Pin with Respect to GND
Junction Temperature
V
TJ
TSTG
TL
°C
°C
°C
Storage Temperature
+150
Lead Temperature (Soldering 10 Seconds)
+260
Human Body Model,
JESD22-A114
2
1
ESD
Electrostatic Discharge Protection Level
kV
Charged Device Model,
JESD22-C101
Note:
2. Lesser of 6.0V or VIN + 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
Parameter
Min.
2.7
0
Typ.
Max.
5.5
Units
VCC
IOUT
L
Supply Voltage Range
Output Current
Inductor
V
500
mA
µH
µF
µF
°C
°C
2.2
2.2
4.7
CIN
COUT
TA
Input Capacitor
Output Capacitor(3)
Operating Ambient Temperature
Operating Junction Temperature
–40
–40
+85
TJ
+125
Thermal Properties
Symbol
Parameter
Junction-to-Ambient Thermal Resistance(4)
Min.
Typ.
Max.
Units
ΘJA
Note:
3. Refer to Operation Description section for guidance on maximum COUT capabilities.
285
°C/W
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 TJ(max) at a given ambient temperate TA.
© 2009 Fairchild Semiconductor Corporation
FAN5358 • Rev. 1.0.1
www.fairchildsemi.com
3
Electrical Characteristics
Minimum and maximum values are at VIN = 2.7V to 5.5V, TA = -40°C to +85°C, circuit of Figure 1 unless otherwise noted.
Typical values are at TA = 25°C, VIN =3.6V.
Symbol
Parameter
Conditions
Min.
Typ.
Max. Units
Power Supplies
IQ
Quiescent Current
No Load, EN=VIN
25
48
µA
I(SD)
Shutdown Supply Current
EN = GND
Rising VIN
0.05
2.4
1.00
2.6
µA
V
VUVLO
Under-Voltage Lockout Threshold
VUVHYST Under-Voltage Lockout Hysteresis
225
mV
V
V(ENH)
V(ENL)
Enable HIGH-Level Input Voltage
Enable LOW-Level Input Voltage
Enable Input Leakage Current
1.2
0.4
V
I(EN)
EN = VIN or GND
In PWM Mode
0.01
2
1.00
µA
Oscillator
fOSC
Switching Frequency
MHz
Regulation
1.0V
ILOAD = 0 to 500mA
ILOAD = 0 to 500mA
ILOAD = 0 to 500mA
ILOAD = 0 to 500mA
From EN Rising Edge
-4.5
-4.5
-4.5
-4.0
+4.5
+4.5
+4.5
+4.0
1.2V
1.3V
1.8V
Output Voltage
Accuracy
VO
%
tSS
Soft-Start
70
µs
Output Driver
PMOS On Resistance
V
IN = VGS = 3.6V
750
650
850
150
20
mΩ
mΩ
mA
°C
RDS(on)
NMOS On Resistance
PMOS Peak Current Limit
Thermal Shutdown
VIN = VGS = 3.6V
Open-Loop(1)
ILIM
TTSD
THYS
750
1150
Thermal Shutdown Hysteresis
°C
Note:
5. The Electrical Characteristics table reflects open-loop data. Refer to Operation Description and Typical Characteristic for
closed-loop data.
Block Diagram
VIN
EN
Q1
CIN
U1
REF
LOGIC
&
GATE
DRIVE
L1
SW
VOUT
COUT
VOUT
GND
RAMP
GEN
Q2
GND
Figure 3. IC Block Diagram
© 2009 Fairchild Semiconductor Corporation
FAN5358 • Rev. 1.0.1
www.fairchildsemi.com
4
Typical Characteristics
Unless otherwise noted, VIN = VEN = 3.6V, VOUT = 1.8V, and TA = 25°C.
100
90
80
70
60
95
90
85
80
75
VIN=3.6V
70
2.7VIN
-40°C
25°C
85°C
65
3.6VIN
4.2VIN
60
0.001
0.01
0.1
1
0.001
0.01
0.1
1
Load Current (A)
Load Current (A)
Figure 4. Efficiency vs. Load Current and Input Supply
Figure 5. Efficiency vs. Load Current and Temperature
20
1.815
1.810
1.805
1.800
15
10
1.795
2.7VIN
1.790
1.785
1.780
3.6VIN
4.2VIN
5.5VIN
5
2.7VIN
3.6VIN
5.5VIN
0
0
0.1
0.2
0.3
0.4
0.5
0.6
1
10
100
1000
Load Current (A)
Load Current (mA)
Figure 6. Voltage Regulation
Figure 7. Peak-to-Peak Output Voltage Ripple
3.0
180
PFM Border
2.5
2.0
1.5
1.0
0.5
0
Always PWM
PWM Border
160
140
The switching mode
changes at these borders
120
2.7VIN
3.6VIN
5.5VIN
Always PFM
100
80
2.7
3.2
3.7
4.2
4.7
5.2
0
0.1
0.2
0.3
0.4
0.5
0.6
Load Current (A)
Input Voltage (V)
Figure 9. PFM / PWM Boundaries
Figure 8. Switching Frequency vs. Load Current
© 2009 Fairchild Semiconductor Corporation
FAN5358 • Rev. 1.0.1
www.fairchildsemi.com
5
Typical Characteristics
Unless otherwise noted, VIN = VEN = 3.6V, VOUT = 1.8V, and TA = 25°C.
2.7VIN
32
3.6VIN
5.5VIN
30
28
26
24
22
-40
-20
0
20
40
60
80
Ambient Temperature (deg.C)
Figure 10. Quiescent Current vs. Input Voltage and Temperature
Figure 11. Line Transient 3.3VIN to 3.9VIN,
50mA Load, 10µs/div.
Figure 12. Line Transient 3.3VIN to 3.9VIN,
250mA Load, 10µs/div.
© 2009 Fairchild Semiconductor Corporation
FAN5358 • Rev. 1.0.1
www.fairchildsemi.com
6
Typical Characteristics
Unless otherwise noted, VIN = VEN = 3.6V, VOUT = 1.8V, and TA = 25°C.
Figure 13. Load Transient 0 to 150mA, 3.6VIN, 5µs/div.
Figure 14. Load Transient 50 to 250mA, 3.6VIN, 5µs/div.
Figure 15. Load Transient 200 to 500mA, 3.6VIN, 5µs/div.
Figure 16. Metallic Short Applied at VOUT, 50μs/div.
© 2009 Fairchild Semiconductor Corporation
FAN5358 • Rev. 1.0.1
www.fairchildsemi.com
7
Typical Characteristics
Unless otherwise noted, VIN = VEN = 3.6V, VOUT = 1.8V, and TA = 25°C.
Figure 17. Overload Recovery to Light Load, 100μs/div.
Figure 18. Soft-Start, RLOAD = 6Ω, 20μs/div.
Figure 19. Power Supply Rejection Ratio at 200mA Load
© 2009 Fairchild Semiconductor Corporation
www.fairchildsemi.com
FAN5358 • Rev. 1.0.1
8
Operation Description
The FAN5358 is a step-down switching voltage regulator
that delivers a fixed output from an input voltage supply of
Under-Voltage Lockout (UVLO)
2.7V to 5.5V. Using
a proprietary architecture with
When EN is HIGH, the under-voltage lockout keeps the part
from operating until the input supply voltage rises high
enough to properly operate. This ensures no misbehavior of
the regulator during startup or shutdown.
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.
Current Limiting
A heavy load or short circuit on the output causes the current
in the inductor to increase until a maximum current threshold
is reached in the high-side switch. Upon reaching this point,
the high-side switch turns off, preventing current from
increasing further.
Control Scheme
The FAN5358 uses a proprietary, non-linear, quasi fixed-
frequency PWM modulator to deliver a fast load transient
response, while maintaining a nominal switching frequency
over a wide range of load conditions. The regulator
performance is independent of the output capacitor ESR,
allowing the use of ceramic output capacitors.
After 12 consecutive PWM cycles that terminate in current
limit, the IC shuts down. About 275μs after shutting down,
the IC attempts to restart. If the fault has not cleared, the IC
continues to shut down, then attempts to restart as shown in
Figure 16.
For very light loads, the device operates in discontinuous
current (DCM) single-pulse PFM mode, which produces low
output ripple compared with other PFM architectures.
Transition between PWM and PFM is near seamless,
exhibiting very little VOUT glitch.
Thermal Shutdown
When the die temperature increases, due to a heavy load
condition and/or high ambient temperature, output switching
is disabled until the die temperature falls sufficiently. The
junction temperature at which the thermal shutdown
activates is nominally 150°C with a 20°C hysteresis. Upon
cooling, the output is enabled and goes through the regular
soft start.
Combined
with
exceptional
transient
response
characteristics, the very low quiescent current of the
controller (25µA) maintains high efficiency, even at very light
loads, while preserving fast transient response for
applications requiring very tight output regulation.
Enable and Soft Start
Maintaining the EN pin LOW keeps the FAN5358 in non-
switching mode in which all circuits are off and the part
draws ~50nA of current. Increasing EN above its threshold
voltage activates the part and starts the soft-start cycle.
During soft start, the output is ramped using a slow RC time
constant. This minimizes any large surge currents on the
input and prevents any overshoot of the output voltage.
Current limit is enforced in case the output cannot keep pace
with the reference or in case of a shorted output.
The current-limit fault response protects the IC in the event
of an over-current condition present during soft-start. This
protection can cause the IC to fail to start if heavy load is
applied during startup or if excessive COUT is used.
Table 2 shows combinations of COUT that allow the IC to start
successfully with the minimum RLOAD that can be supported.
Table 2. Minimum RLOAD Values for Soft-Start with
Various COUT Values
COUT
4.7μF
10μF
Minimum RLOAD
No restriction
VOUT / 0.40
© 2009 Fairchild Semiconductor Corporation
FAN5358 • Rev. 1.0.1
www.fairchildsemi.com
9
Thermal Considerations
Applications Information
Selecting the Inductor
The output inductor must meet both the required inductance
and the energy handling capability of the application.
The FAN5358 is designed to supply a maximum of 500mA,
at the specified output voltage, with an operating junction
temperature of up to 125°C. Once the power dissipation and
thermal resistance is known, the maximum junction
temperature of the device can be calculated. The power
dissipation by the IC can be calculated from the power
efficiency diagram Figure 5 and subtracting the power
dissipated by the inductor due to its serial resistance (ESR).
The inductor value affects the average current limit, the
PWM-to-PFM transition point, the output voltage ripple, and
the efficiency.
The inductor ESR is dependent, not only upon the size and
type of inductor, but also upon the switching frequency,
which depends on the load and VIN. Some inductor
manufacturers provide full information regarding the variation
of the inductor ESR with the switching frequency. This
information can be used to show that, at high switching
frequency (~2 MHz) and maximum load, the power
dissipated by the inductor can exceed the power dissipated
by the IC package itself.
The ripple current (∆I) of the regulator is:
⎛
⎜
⎜
⎝
⎞
⎟
⎟
⎠
VOUT
V
− VOUT
L • fSW
IN
ΔI ≈
•
(1)
V
IN
The maximum average load current, IMAX(LOAD), is related to
the peak current limit, ILIM(PK) by the ripple current:
ΔI
2
(2)
IMAX(LOAD) = ILIM(PK)
−
The actual thermal resistance depends upon the thermal
characteristics of the SC-70 surface-mount package and the
surrounding printed circuit board (PCB) copper to which it is
mounted. This can be improved by providing a heat sink of
surrounding copper ground on the PCB. Depending on the size
of the copper area, the resulting θJA can be reduced below
280°C/W. The addition of backside copper with through holes,
stiffeners, and other enhancements can also help reduce
thermal resistance. The heat contributed by the dissipation of
other devices, particularly the inductor, located nearby, must be
included in the design considerations. Once the limiting
parameters are determined, the design can be modified to
ensure that the device remains within specified operating
conditions even if the maximum load is applied permanently.
The transition between PFM and PWM operation is
determined by the point at which the inductor valley current
crosses zero. The regulator DC current when the inductor
current crosses zero, IDCM, is:
ΔI
2
IDCM
=
(3)
The FAN5358 is optimized for operation with L=2.2µH. The
inductor should be rated to maintain at least 70% of its value
at ILIM(PK)
.
Efficiency is affected by the inductor DCR and inductance
value. Decreasing the inductor value for a given physical
size typically decreases the DCR; but since ∆I increases, the
RMS current increases, as do core and skin effect losses.
In short circuit VOUT-to-GND condition, the FAN5358 is fully
protected and the power dissipated is internally reduced
below 100mW. Overload conditions at minimum VIN should
be considered as worst case, when it is possible for the
device to enter a thermal cycling loop in which the circuit
enters a shutdown condition, cools, re-enables, and again
overheats and shuts down repeatedly due to an unmanaged
fault condition. The diagram in Figure 20 was determined
experimentally, using the recommended two-layer PCB in
still air, to be used as a thermal guide.
ΔI2
12
2
(4)
IRMS
=
IOUT(DC)
+
The increased RMS current produces higher losses through
the RDS(ON) of the IC MOSFETs as well as the inductor ESR.
Increasing the inductor value produces lower RMS currents,
but degrades transient response. For a given physical
inductor size, increased inductance usually results in an
inductor with lower saturation current. Table 3 shows the
effects of inductance higher or lower than the recommended
inductor on regulator performance.
90
Area Where Thermal Protection MayTrigger
85
80
75
70
Safe Operating Area
for 500mA Load
65
60
55
2.7
2.9
3.1
3.3
3.5
Input Voltage (V)
Figure 20. Maximum Ambient Temperature vs.
Input Voltage at 500mA
© 2009 Fairchild Semiconductor Corporation
FAN5358 • Rev. 1.0.1
www.fairchildsemi.com
10
PCB Layout Considerations
There are only three external components: the inductor and
the input and output capacitors. For any buck regulator IC,
including the FAN5358, it is important to place a low-ESR
input capacitor very close to the IC, as shown in Figure 21.
The input capacitor ensures good input decoupling, which
helps reduce noise appearing at the output terminals and
ensures that the control sections of the IC do not behave
erratically due to excessive noise. This reduces switching
cycle jitter and ensures good overall performance. It is
important to place the common GND of CIN and COUT as close
as possible to any of the FAN5358 GND terminals. There is
some flexibility in moving the inductor further away from the
IC; in that case, VOUT should be considered at the COUT
terminal.
Output Capacitor
Table 4 suggests 0402 capacitors. 0603 capacitors may
further improve performance in that the effective capacitance
is higher. This improves the transient response and output
ripple as shown in Table 3.
Increasing COUT has no effect on loop stability and can
therefore be increased to reduce output voltage ripple or to
improve transient response. Output voltage ripple, ∆VOUT, is:
⎛
⎜
⎜
⎝
⎞
⎟
⎟
⎠
1
ΔVOUT = ΔI•
+ ESR
(5)
8 • COUT • fSW
Input Capacitor
The 2.2μF ceramic input capacitor should be placed as close
as possible between the VIN pin and GND to minimize the
parasitic inductance. If a long wire is used to bring power to
the IC, additional “bulk” capacitance (electrolytic or tantalum)
should be placed between CIN and the power source lead to
reduce ringing that can occur between the inductance of the
power source leads and CIN.
The effective capacitance value decreases as VIN increases
due to DC Bias effects. This has no significant impact on
regulator performance.
Figure 21. PCB Layout Guidance
Table 3. Effects of Changes in Inductor Value (from Recommended Value) on Regulator Performance
(5)
Inductor Value
Increase
IMAX(LOAD)
Increase
Decrease
ILIM(PK)
Decrease
Increase
∆VOUT
Transient Response
Degraded
Decrease
Increase
Decrease
Improved
Table 4. Recommended Passive Components and Their Variation Due to DC Bias
Component
Description
Vendor
Min. Typ. Max.
Comment
FDK MIPF2520D
2.2μH, 2520, 100mΩ,1.3A
Minimum value occurs
at maximum current
Hitachi Metal:KSLI -
252010AG-2R2
Murata: LQM31PN2RM00L
TOKO: MDT2520CN2R2M
L1
1.5μH 2.2μH
2.2μH, 2520, 80mΩ,1.3A
Murata or Equivalent
GRM155R60G475M
GRM155R60E475ME760
Decrease primarily due
COUT
4.7μF, X5R, 0402
2.2μF, X5R, 0402
1.6μF 4.7μF 5.2μF
1.0μF 2.2μF 2.4μF
to DC bias (VOUT
)
Murata or Equivalent
GRM155R60J225ME15
GRM188R60J225KE19D
Decrease primarily due
to DC bias (VIN) and
elevated temperature
CIN
© 2009 Fairchild Semiconductor Corporation
FAN5358 • Rev. 1.0.1
www.fairchildsemi.com
11
Physical Dimensions
SYMM
C
L
2.00±0.20
A
0.65
0.50 MIN
6
4
B
PIN ONE
1.25±0.10
1.90
1
3
0.30
0.15
(0.25)
0.65
0.40 MIN
1.30
M
0.10
A B
LAND PATTERN RECOMMENDATION
1.30
SEE DETAIL A
1.00
0.80
1.10
0.80
0.10
C
0.10
0.00
C
2.10±0.30
SEATING
PLANE
NOTES: UNLESS OTHERWISE SPECIFIED
A) THIS PACKAGE CONFORMS TO EIAJ
SC-88A
GAGE
B) ALL DIMENSIONS ARE IN MILLIMETERS.
C) DIMENSIONS DO NOT INCLUDE BURRS
OR MOLD FLASH.
PLANE
(R0.10)
D) DRAWING FILENAME AND REVISION;
MAA06AREV6
0.25
0.10
0.20
0.46
0.26
30°
0°
DETAIL A
SCALE: 2X
Figure 22. 6-Lead SC70
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/.
© 2009 Fairchild Semiconductor Corporation
FAN5358 • Rev. 1.0.1
www.fairchildsemi.com
12
© 2009 Fairchild Semiconductor Corporation
FAN5358 • Rev. 1.0.1
www.fairchildsemi.com
13
相关型号：
©2020 ICPDF网 联系我们和版权申明