Dual Input Li-Ion Battery Charger with Adjustable Output 600mA Synchronous Buck Converter

LTC News for Immediate Release
For more information, tel. 408-432-1900
Doug Dickinson, Media Relations Mgr., ext. 2233
John Hamburger, Dir., Mkting Comm., ext. 2419
Dual Input Li-Ion Battery Charger with
Adjustable Output 600mA Synchronous Buck Converter
MILPITAS, CA – April 20, 2006 – Linear Technology Corporation announces the
LTC3550, an efficient, compact power management solution for handheld applications. The
device incorporates a dual input Li-Ion/Polymer battery charger and a high efficiency
synchronous buck regulator in a low-profile 16-lead 3mm x 5mm DFN package. The linear
battery charger automatically selects the appropriate power source to efficiently charge
single-cell Li-Ion batteries via a wall adapter up to 8V (10V abs max) or a USB port.
Standalone operation simplifies design, eliminating the need for an external microprocessor
for charge termination. Using a constant-current/constant-voltage algorithm, the charger can
deliver up to 950mA of charge current from a wall adapter supply, or up to 500mA of charge
current from a USB supply. The final float voltage accuracy is ±0.6%. The LTC3550’s
battery charger is equipped with a patented thermal regulation scheme that maximizes the
charge rate without the risk of overheating. To preserve battery energy, it draws <6uA from
the battery terminal in standby and <1uA in shutdown mode.
The LTC3550’s integrated synchronous buck regulator features an adjustable
output voltage from 5.5V to as low as 0.6V, delivering up to 600mA of continuous output
current. It uses internal switches with an RDS(ON) of only 0.40 Ohm to deliver efficiencies
as high as 96%, maximizing battery run time. In addition, automatic Burst Mode®
operation optimizes efficiency at light loads, featuring a quiescent current of only 20uA
(<1uA in shutdown). Using a constant frequency current mode architecture, the buck
regulator operates from an input voltage range of 2.5V to 5.5V. Its 1.5MHz switching
frequency allows the utilization of tiny low cost capacitors and inductors less than 1mm in
height. Furthermore, the regulator is stable with ceramic output capacitors, achieving low
output voltage ripple.
The LTC3550 is available from stock in a compact 5mm x 3mm x 0.75mm
DFN-16 package. Pricing starts at $2.00 each for 1,000-piece quantities.
Dual Input Li-Ion Battery Charger with
Adjustable Output 600mA Synchronous Buck Converter
Page 2
Summary of Features: LTC3550
Charges Single-Cell Li-Ion Batteries from Wall Adapter & USB Inputs
10V Compliance for Wall Adapter Input
Automatic Input Power Detection & Selection
Charge Current Programmable up to 950mA from Wall Adapter Input
High Efficiency 600mA Synchronous Buck Regulator
Buck Regulator Adjustable Output Voltage: 0.6V to 5.5V
No External MOSFET, Sense Resistor or Blocking Diode Needed
Thermal Regulation Maximizes Charging Rate without Overheating
Preset Charge Voltage with ±0.6% Accuracy
Programmable Charge Current Termination
1.5MHz Constant Frequency Operation (Buck Converter)
18uA USB Suspend Current in Shutdown
Charge Status Output
Automatic Recharge
Thermally-Enhanced, Low Profile (0.75mm) 16-Lead 3mm x 5mm DFN Package
Company Background
Linear Technology Corporation, a manufacturer of high performance linear integrated
circuits, was founded in 1981, became a public company in 1986 and joined the S&P 500
index of major public companies in 2000. Linear Technology products include high
performance amplifiers, comparators, voltage references, monolithic filters, linear regulators,
DC-DC converters, battery chargers, data converters, communications interface circuits, RF
signal conditioning circuits, and many other analog functions. Applications for Linear
Technology’s high performance circuits include telecommunications, cellular telephones,
networking products such as optical switches, notebook and desktop computers, computer
peripherals, video/multimedia, industrial instrumentation, security monitoring devices,
high-end consumer products such as digital cameras and MP3 players, complex medical
devices, automotive electronics, factory automation, process control, and military and space
systems. For more information, visit www.linear.com
Doug Dickinson, Media Relations Manager
Linear Technology Corporation
1630 McCarthy Boulevard
Milpitas, CA 95035-7417
[email protected]
READER SERVICE: Call toll-free 1-800-4-LINEAR (for literature only), or go to the company’s web site:
Note: LT, LTC, Burst Mode and
are registered trademarks of Linear Technology Corp.
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