AAT1218 Datasheet, PDF (1/15 Pages) Advanced Analogic Technologies – 1A, 1.2MHz Synchronous Boost Converter

SwitchReg^TM
PRODUCT DATASHEET
AAT1218
1A, 1.2MHz Synchronous Boost Converter
General Description
The AAT1218 is a general purpose DC/DC synchronous
boost (step-up) converter providing a tightly regulated
DC output voltage for continuous output currents up to
1A (minimum). Operating input voltage must be less
than the output voltage and in the 0.5V to 5.5V range,
making the device well suited to portable equipment and
consumer appliances.
The boost output voltage is programmed from 2.5V to
5.5V with an external resistor divider. Optimized internal
compensation provides fast transient response with no
external components.
Synchronous rectification eliminates the need for an
external rectifier for output voltage less than 4.5V. Low
on-resistance internal switches provide efficiency up to
95%, which minimizes losses and simplifies packaging
and circuit board layout. An inductor, two resistors and
two ceramic output capacitors are all that are required to
implement a DC/DC boost solution.
The switching frequency is internally set to 1.2MHz to
minimize external filter size and optimize switching
losses.
Integrated soft-start ensures minimal inrush current.
The “anti-ring” circuit reduces stray EMI during light
load, discontinuous operation. Input quiescient current is
less than 400μA at no load.
The device provides cycle-by-cycle current limit and over-
temperature protection to prevent device over-stress.
The AAT1218 is available in a Pb-free, 12-pin low profile
TDFN33 package or a 12-pin TSOPJW package; both
packages are rated from -40°C to 85°C.
Typical Application
Features
• 2.5V to 5.5V Adjustable Output Voltage
• 0.5V Minimum Input Voltage
• ±2% Output Accuracy
• No Schottky Diode Required (V_{OUT < 4.5V)}
• Up to 95% Efficiency
• 400μA Standby Current
• <1μA Shutdown Current
• Integrated Soft-Start Circuitry Limits Inrush Current
• Constant Frequency 1.2MHz Operation
▪ Inductor Height <1.8mm
▪ ^{Small Ceramic Capacitors}
• Anti-ring Circuit Reduces EMI
• Current Mode Control
▪ Fast, Stable Transient Response
▪ No External Compensation
▪ Cycle-by-Cycle Current Limit
• Low Inrush Current with 0.7ms Soft-start
• Low Output Ripple: <80mVpp for all Loading Conditions
(BW = 25MHz)
• Over-Temperature Protection
• Adjustable and Fixed Output Versions Available
• Delivers 1A to 5V Output from a Single Cell Li+
Battery
• Low-profile TDFN33-12 or TSOPJW-12 Package
Applications
• DVD Players
• Hard Disk Drive
• MP3 Players
• PDA
• Portable Computers
• Smart Phones
VIN: 3.6V
L1
2.2µH
CIN
22µF
0805
LX
OUT
VIN
AAT1218
EN
FB
GND
PGND
VOUT: 5V @ 1A
COUT
44µF
(2x22µF)
0805
1218.2008.10.1.1
www.analogictech.com
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