Battery charger with SmartStart

The new compact standalone linear single 1-cell Li-ion battery charger from Linear Technology Corp. offers advanced features for charging safely, increased charge termination flexibility, improved status reporting, and prolonged battery life.

For safety, the new LTC4062 is equipped with an adjustable timer for charge termination and a precision float voltage to prevent overcharging of the cell. To eliminate the risk of overheating while charging at a maximum rate, a patented thermal regulation circuit keeps the device's junction temperature at a safe level. Moreover, I/O pins report the state-of-charge during trickle, normal and end-of-charge modes.

The LTC4062 includes an integrated precision, micropower comparator, which is an undedicated comparator with a general purpose input and open-drain output. The device can charge Li-ion batteries to a 4.2V float voltage with ±0.35 percent accuracy. It also does not require an external sense resistor, MOSFET or blocking diode, thereby simplifying design. Additionally, the LTC4062 includes a soft-start circuit to minimize inrush current at the start of a charge cycle. And for USB-powered charging, the logic pin from a USB controller can select low power or high power compliant charge currents, eliminating dependence on external discrete components. At any point in the charge cycle, the new battery charger can be shut down, limiting battery current drain to less than 2?A.

The LTC4062 prolongs battery life by eliminating unnecessary re-charge cycles with its SmartStart feature. Since frequent recharge cycles decrease battery capacity and shorten battery life, SmartStart operation prevents a new charge cycle from starting if the battery voltage is above 4.1V. The chip also offers several methods of charge termination such as user adjustable current and charge time, external digital control, or automatic C/10.

The LTC4062 is housed in a 10-lead 3-by-3-by-0.75mm DFN package and 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, pricing starts at $1.95 each.