Integrated Li-Ion Linear Charger does not overheat.
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Press Release Summary:
Housed in 6-lead, 2 x 2 mm DFN package, single-cell LTC4059 monitors and reports value of charge current. System requires input capacitor and charge current program resistor. With proper PCB layout design, product can safely charge single-cell, Li-Ion battery from 5 V input at up to 900 mA. Thermal regulation scheme automatically reduces charge current as necessary during high ambient temperature conditions to maintain thermal control.
Original Press Release:
900mA, Fully Integrated Li-Ion Linear Charger in 2mm x 2mm DFN Does Not Overheat
MILPITAS, CA - December 22, 2003 - Linear Technology Corporation introduces the LTC4059, a tiny single-cell Li-Ion linear charger that eliminates the need for three discrete power components, fast charges without any risk of system overheating, monitors and reports the value of the charge current and is offered in the smallest possible package without compromising thermal performance. The complete solution requires only two discrete components (input capacitor and charge current program resistor) and fits in a 2.5mm x 2.7mm footprint. The LTC4059's 2mm x 2mm DFN package has less than half the footprint of a SOT-23 package and offers up to 60°C/W lower thermal resistance for improved heat dissipation. With proper PCB layout design, the LTC4059 can safely charge a single-cell, Li-Ion battery from 5V input at up to 900mA. Moreover, it is not necessary to design for worst-case power dissipation scenarios since the LTC4059's patented thermal regulation scheme automatically reduces charge current as necessary during high ambient temperature conditions to maintain thermal control. Applications include digital still cameras, and portable POS and diagnostic equipment as well as cell phones, PDAs and USB-equipped handheld devices.
The LTC4059 requires no external MOSFET, current sense resistor or reverse current blocking diode. Charge current is adjustable with an off-the-shelf standard resistor. The LTC4059 operates from input supplies ranging from 3.75V to 8V including USB ports. During shutdown, the supply current is only 10uA and battery drain current is less than 1uA. A charge current monitor pin produces a voltage that is proportional to the charge current. A microprocessor can use this voltage for charge termination and control. In addition, the LTC4059 can be configured as a constant-current source for charging NiMH/NiCd batteries.
The LTC4059 is rated for operation from -40°C to 85°C. 1,000-piece pricing starts at $1.35 each.
Summary of Features: LTC4059
Programmable Charge Current up to 900mA with ±5% Accuracy
Charge current monitor output for charge termination
Constant-Current/Constant-Voltage Operation with Thermal Regulation to Maximize Charging Range without Risk of Overheating
Constant-Current Source Mode for Charging Nickel Based Batteries
No External MOSFET, Sense Resistor or Blocking Diode
Preset 4.2V Charge Voltage with 0.6% Accuracy
Tiny 6-Lead 2mm x 2mm DFN Package
Company Background
Linear Technology Corporation was founded in 1981 as a manufacturer of high performance linear integrated circuits. Linear Technology products include operational, instrumentation and audio amplifiers; voltage regulators,power management devices, DC-DC converters and voltage references; comparators; monolithic filters; communications interface circuits; one-chip data acquisition sub-systems; pulse-width modulators and sample-and-hold devices; and high frequencydevices. Applications for Linear Technology's high performance circuits include wireless and broadband telecommunications infrastructure, cellular telephones, networking products and satellite systems, notebook and desk top computers, computer peripherals, video/multimedia, industrial and medical instrumentation, automotive electronics, factory automation, process control, military and space systems, and high-end consumer products including digital cameras, MP3 players and other electronic products.
Note: LT, AND LTC are registered trademarks of Linear Technology Corp.
