A standalone linear battery charger crafted by Linear Technology prolongs the life of one-cell lithium-ion (Li-ion) batteries used in backup applications (see the figure).
The LTC4064 mainly targets industrial systems like redundant array of inexpensive disks (RAID) servers, where Li-ion cells provide backup power supplies. Such supplies may be required to provide three years or more of backup power.
By charging to a float voltage of 4.0 V rather than the usual 4.1 or 4.2 V, the charger slows aging and capacity degradation when the battery is not in use but must remain fully charged for extended periods of time. Pricing for the MSOP-housed chip starts at $1.85 each per 1000.
A similar development, the highly integrated AMIS-70020 IC, hails from AMI Semiconductor. It simplifies the design of circuits needed to measure power-failure durations in industrial applications. The chip can measure power-failure durations of up to five hours with a one-second resolution. It also offers autonomous stop/start operation. During the counting phase, an external capacitor or a lithium coin-cell battery can power the device. Current consumption is less than 1 µA.
Housed in an SO-8 package, the AMIS-70020 integrates all of the necessary counter functionality along with a 1-kHz oscillator, a two-wire interface, and power-management circuitry for recharging an external capacitor. Combined with the external components (filter capacitor and buffer capacitor or battery), the circuit's overall footprint is approximately 15 mm2. The AMIS-70020 costs $1.48 each per 1000 pieces.