Fremont Micro Devices
FT441
1.5MHz, 900mA Synchronous Step-Down Converter
FEATURES
High Efficiency - Up to 95%
Guaranteed 900mA Output Current
2.5V to 5.5V Input Voltage Range
1.5MHz Constant Frequency Operation
No external Schottky Diode Needed
Adjustable Output Voltages From 0.6V to VIN
Fixed Output Voltage Options Available
100% Duty Cycle Low-Dropout Operation
0.1μA Shutdown Current
SOT23-5 Package
DESCRIPTION
The FT441 is a 1.5MHz constant frequency, slope
compensated current mode step down converter.
It is
ideal for portable equipment requiring very high
current up to 0.9A from single-cell Lithium-ion
batteries while still achieving over 90% efficiency
during peak load conditions.
The FT441 integrates a main switch and a
synchronous rectifier for high efficiency without an
external Schottky diode. The FT441 automatically
turns off the synchronous rectifier to increase
efficiency while enters discontinuous PWM mode.
The FT441 can run at 100% duty cycle for low
dropout operation, maximizing battery life in portable
application. FT441 consumes less than 1uA when
enter shutdown mode.
The FT441 is available in a fixed output voltages of
1.2V, 1.5V, and 1.8V, and is also available in an
adjustable
output
voltage
version
capable
of
generating output voltages from 0.6V to VIN .The
FT441 is available in a 5-pin SOT23-5 package.
TYPICAL APPLICATIONS
Cellular phones
DSP Core Supplies
XDSL Applications
USB Powered Modems
Digital Still Cameras
Portable Instruments
PC Cards and Notebooks
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TYPICAL APPLICATION CIRCUIT
FT441
VIN 2.7~4.2V
4
V
IN
FT441
SW
3
L1 2.2uH
Vout 1.8V
C2
22pF
C1
10uF
1
EN
GND
2
V
FB
5
R2
200K
R1
100K
C3
10u
F
Figure 1: Typical Application Circuit
ABSOLUTE MAXIMUM RATINGS
VIN to GND……………………………….……………………………………………………………-0.3V to 6V
EN to GND..…………………………………………….……………………………….. ……-0.3V to (VIN+0.3)
VFB to GND..…………………………………………………………………………………. -0.3V to (VIN+0.3)
SW to GND………………….…………………………………………………………….……-0.3V to (VIN+0.3)
Peak SW Sink and Source Current……………...……………………………………………….Internally Limited
Junction to Ambient Thermal Resistance (θ
JA
).…………………….……………………………………250℃/W
Operating Temperature Range……………….……………………………………………………...-40℃ to +85℃
Junction Temperature………………………………………………………………………..….... -40℃ to +150℃
Storage Temperature Range …………………………..……………………………………….….-55℃ to +150℃
Lead Temperature (Soldering, 10sec) …………………………………………………………………...…...300℃
Stresses exceeding Maximum Ratings may damage the device. Maximum Ratings are stress ratings only.
Functional operation above the Recommended Operating Conditions is not implied. Extended exposure to
stresses above the Recommended Operating Conditions may affect device reliability
.
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PIN COMFIGURATION
FT441
Figure 2: Package Top View
TERMINAL DEFINITION
Pin
1
2
3
4
5
Name
EN
GND
SW
V
IN
V
FB
/V
out
Enable control input
Ground
Switching node, connecting to inductor
Power input
Feedback node. VFB for adjustable version, and Vout for fixed output version
Table 1
Description
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ORDERING INFORMATION
FT441
①②
Designator
A
B
C
①
D
E
F
G
Designator
②
a
Symbol
Table 2
Symbol
ADJ
1.5V
1.8V
2.5V
1.2V
2.8V
3.3V
Package Type
SOT23-5
Output Voltage
FT441
MARKING RULE
5
4
.
①
Represent Product Series
Symbol
1
②
Represent Output Voltage
③
Represent Package Tape
④⑤
For internal reference
①②③④⑤
1
2
Figure 3
3
Product Series
FT441xx
Table 3
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BLOCK DIAGRAM
FT441
Figure 4: FT441 Block Diagram
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