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PDF FAN4855 Data sheet ( Hoja de datos )
| Número de pieza | FAN4855 | |
| Descripción | High Efficiency Boost Regulator | |
| Fabricantes | Fairchild Semiconductor | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de FAN4855 (archivo pdf) en la parte inferior de esta página. Total 12 Páginas | ||
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www.DataSheet4U.com
December 2005
FAN4855
500mA High Efficiency Boost Regulator with Adjustable
Output, Shutdown and Low Battery Detect
Features
■ Low power PFM boost regulator
■ Input voltage range is from 1.6V to 4.5V
■ Output voltage range is from 3V to 5V
■ 500mA maximum load current capability
■ 95% efficient power conversion
■ 2-3 cell and single cell Li-Ion systems
■ Variable on-time Pulse Frequency Modulation (PFM)
■ Internal synchronous rectifier (no need for external
diode)
■ Low-battery detection
■ Logic controlled shutdown with true-load disconnect
■ Low (80µA) quiescent current
■ TSSOP-8 Package
Applications
■ DSCs
■ PDAs
■ Cell phones, smart phones
■ Portable instrumentations
■ 2-3 AA / AAA cells operated devices
■ Single cell Li-Ion operated devices
General Description
The FAN4855 is a low power boost regulator designed
for low voltage DC to DC conversion in 2-cell battery
powered systems such as digital cameras, cell phones
and PDAs. The converter starts-up at 1.3V and operates
after the start at an input voltage as low as 1V. Output
voltage can be adjusted by external resistors from 3.3V
to 5V with a maximum load current of 0.5A. Quiescent
current in shut-down mode is less than 10µA, which
maximizes the battery live time. The ON time changes
with the input voltage to maintain the ripple current con-
stant and to provide the highest efficiency over a wide
load range—while maintaining low peak currents in the
boost inductor. The combination of built-in power transis-
tors, synchronous rectification and low supply current,
make the FAN4855 ideal for portable applications. The
FAN4855 is available in 8-lead TSSOP package.
Ordering Information (TA = -40°C to +85°C)
Part Number
FAN4855MTC
FAN4855MTCX
Package
8 Pin TSSOP
8 Pin TSSOP
Packing
Rails
Tape and Reel
Typical Application
Input 1.6V
to 4.5V
On
Off
Low Battery
Detect In
Low Battery
Detect Out
FAN4855
1 VIN
GND 8
2 SHDN VL 7
3 LBI
4 LB0
VOUT 6
FB 5
Output 3.3V to 5V
up to 0.5A
©2005 Fairchild Semiconductor Corporation
FAN4855 Rev. 1.0.1
1
www.fairchildsemi.com
1 page  
Typical Operating Characteristics (L = 10µH, CIN = 47µF, COUT = 47µF/1.0µF, T = 25°C)
Load Current vs. Start-Up Voltage
(Resistive Load)
600
500
VOUT = 3.3V
400
300
VOUT = 5V
200
100
0
1.5 2 2.5 3 3.5
Input Voltage, V
4
100.0
90.0
80.0
70.0
60.0
50.0
40.0
30.0
20.0
10.0
0.0
0.1
Efficiency vs. Load Current
Vout = 3.3V
Vin=3V
Vin=2.0V Vin=1.5V
1 10 100
Output Current, mA
1000
100.0
90.0
80.0
70.0
60.0
50.0
40.0
30.0
20.0
10.0
0.0
0.1
Efficiency vs. Load Current
Vout = 5V
Vin=3V
Vin=2.0V Vin=1.5V
1 10 100
Output Current, mA
1000
2.3
2.1
1.9
1.7
1.5
1.3
1.1
0.9
0.7
0.5
1.5
SHDN Threshold Voltage
2 2.5 3 3.5 4
Input Voltage, V
4.5
4
3.5
3
2.5
2
1.5
1
0.5
0
0.6
Starting Up and Turning Off
VOUT = 3.3V, Iloads = 10mA to 50mA
TURN OFF:
Iload=50mA
Iload=10mA
START UP
0.8 1.0 1.2 1.4 1.6
Input Voltage, V
1.8
5
4
3
2
1
0
0.6
Starting Up and Turning Off
VOUT = 5V, Iloads = 10mA to 50mA
Iload=50mA
Iload=10mA
START UP
Iload=10mA to 50mA
TURN OFF:
0.8 1.0 1.2 1.4 1.6 1.8
Input Voltage, V
FAN4855 Rev. 1.0.1
5
www.fairchildsemi.com
5 Page 
Mechanical Dimensions
Package: T08, 8-Pin TSSOP
0.113 - 0.123
(2.87 - 3.12)
8
PIN 1 ID
0.169 - 0.177 0.246 - 0.258
(4.29 - 4.50) (6.25 - 6.55)
1
0.026 BSC
(0.65 BSC)
0.043 MAX
(1.10 MAX)
0°-8°
0.033 - 0.037 0.008 - 0.012
(0.84 - 0.94) (0.20 - 0.30)
0.002 - 0.006
(0.05 - 0.71)
SEATING PLANE
0.020 - 0.028
(0.51 - 0.71)
0.004 - 0.008
(0.10 - 0.20)
FAN4855 Rev. 1.0.1
11
www.fairchildsemi.com
11 Page | ||
| Páginas | Total 12 Páginas | |
| PDF Descargar | [ Datasheet FAN4855.PDF ] | |
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