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Battery charger improves charging safety, prolongs battery life

Posted: 21 Jan 2005 ?? ?Print Version ?Bookmark and Share

Keywords:linear technology? battery charger? ltc4061?

Linear Technology Corp. introduced a compact standalone linear 1-cell Li-ion battery charger with features that promise to improve charging safety, simplify charge termination and status reporting, and prolong battery life.

For safety, the new LTC4061 is equipped with a thermistor interface for temperature qualified charging, an adjustable timer as a backup charge termination, and precision float voltage to prevent overcharging of the cell. To eliminate the risk of overheating while charging at maximum rate, a patented thermal regulation circuit keeps the device's junction temperature at a safe level. In addition, I/O pins report the state-of-charge during trickle, normal and end-of-charge modes as well as indicate the presence of an AC adapter or faulty battery.

SmartStart feature

According to the company, its new product prolongs battery life by eliminating unnecessary re-charge cycles with its SmartStart feature. The IC offers four methods for charge termination: user adjustable current and time, external digital control or automatic C/10.

The LTC4061 can charge both 4.2V and the new 4.4V float voltage Li-ion batteries with 0.5 percent and 0.35 percent accuracy, respectively. It requires no external sense resistor, MOSFET or blocking diode, simplifying design. Additionally, the LTC4061 includes a soft-start circuit to minimize the inrush current at the start of a charge cycle. For USB powered charging, the logic pin from a USB controller can select the charge current, eliminating dependence on external discrete components. After a battery is fully charged, the LTC4061 enters a standby mode. Because frequent re-charge cycles decrease battery capacity and shorten battery life, the SmartStart feature starts re-charging the battery only if the battery voltage drops below 4.1V. This feature reduces the number of unnecessary charge cycles, prolonging battery life. At any point in the charge cycle, the LTC4061 can be shutdown, limiting battery drain current to <2?A.

Housed in a 10-lead 3-by-3mm DFN package, the LTC4061 is designed for charging a battery from a wall adapter or USB in MP3 players, digital cameras, PDAs and cellphones. For 1,000-piece orders, price starts at $1.95.

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