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PDF FAN5358 Data sheet ( Hoja de datos )
| Número de pieza | FAN5358 | |
| Descripción | SC70 Synchronous Buck Regulator | |
| Fabricantes | Fairchild Semiconductor | |
| Logotipo |  |
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September 2009
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
Applications
Cell Phones, Smart Phones
3G, 4G, WiFi®, WiMAX™, and WiBro® Data Cards
Netbooks®, Ultra-Mobile PCs
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.
www.DaTtaySpheiceta4Ul .cAopmplication
L1 SW 1
6 VIN
GND 2 U1 5 GND CIN
VOUT
COUT
3
4 EN
Figure 1. FAN5358 Typical Application
Table 1. External Components for Figure 1
U1
FAN5358
fSW
2MHz
L1
2.2μH
CIN
2.2μF
COUT
4.7μF
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
1 page  
Typical Characteristics
Unless otherwise noted, VIN = VEN = 3.6V, VOUT = 1.8V, and TA = 25°C.
95 100
VIN=3.6V
90
85 90
80
80
75
70
65
60
0.001
2.7VIN
3.6VIN
4.2VIN
0.01
0.1
Load Current (A)
1
Figure 4. Efficiency vs. Load Current and Input Supply
1.815
1.810
1.805
1.800
1.795
1.790
1.785
1.780
0
www.DataSheet4U.com
2.7VIN
3.6VIN
4.2VIN
5.5VIN
0.1 0.2 0.3 0.4
Load Current (A)
0.5
Figure 6. Voltage Regulation
3.0
0.6
2.5
2.0
1.5
1.0
0.5
0
0
2.7VIN
3.6VIN
5.5VIN
0.1 0.2 0.3 0.4 0.5 0.6
Load Current (A)
Figure 8. Switching Frequency vs. Load Current
70
60
0.001
-40°C
25°C
85°C
0.01
0.1
Load Current (A)
1
Figure 5. Efficiency vs. Load Current and Temperature
20
15
10
5 2.7VIN
3.6VIN
0 5.5VIN
1 10
100
Load Current (mA)
1000
Figure 7. Peak-to-Peak Output Voltage Ripple
180
PFM Border
160
Always PWM
PWM Border
140
The switching mode
changes at these borders
120
100 Always PFM
80
2.7 3.2 3.7 4.2 4.7 5.2
Input Voltage (V)
Figure 9. PFM / PWM Boundaries
© 2009 Fairchild Semiconductor Corporation
FAN5358 • Rev. 1.0.1
5
www.fairchildsemi.com
5 Page 
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:
ΔVOUT
=
ΔI •
⎜⎜⎝⎛
8
•
1
COUT
•
fSW
+ ESR ⎟⎟⎠⎞
(5)
Figure 21. PCB Layout Guidance
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.
Table 3. Effects of Changes in Inductor Value (from Recommended Value) on Regulator Performance
Inductor Value
Increase
Decrease
www.DataSheet4U.com
IMAX(LOAD)
Increase
Decrease
ILIM(PK)
Decrease
Increase
∆VOUT(5)
Decrease
Increase
Transient Response
Degraded
Improved
Table 4. Recommended Passive Components and Their Variation Due to DC Bias
Component
Description
Vendor
Min. Typ. Max.
Comment
L1
COUT
CIN
2.2μH, 2520, 100mΩ,1.3A
2.2μH, 2520, 80mΩ,1.3A
4.7μF, X5R, 0402
2.2μF, X5R, 0402
FDK MIPF2520D
Hitachi Metal:KSLI -
252010AG-2R2
Murata: LQM31PN2RM00L
TOKO: MDT2520CN2R2M
Murata or Equivalent
GRM155R60G475M
GRM155R60E475ME760
Murata or Equivalent
GRM155R60J225ME15
GRM188R60J225KE19D
1.5μH
1.6μF
1.0μF
2.2μH
4.7μF
2.2μF
5.2μF
2.4μF
Minimum value occurs
at maximum current
Decrease primarily due
to DC bias (VOUT)
Decrease primarily due
to DC bias (VIN) and
elevated temperature
© 2009 Fairchild Semiconductor Corporation
FAN5358 • Rev. 1.0.1
11
www.fairchildsemi.com
11 Page | ||
| Páginas | Total 13 Páginas | |
| PDF Descargar | [ Datasheet FAN5358.PDF ] | |
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