Charger has 40V operation to suit variety of input sources

8th August 2014

Staff Reporter

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Datasheet

Designed for Lithium-Ion, LiFePO4 and lead-acid batteries, the LTC4121 is a constant-current/constant-voltage 400mA charger. The charger, from Linear Technologies, is suited for a variety of battery chemistries due to the programmable 3.5V to 18V battery charge voltage range with tight ±1% accuracy. The LTC4121-4.2, the fixed output float voltage version, is suitable for 1S lithium-ion battery packs.

The device's synchronous step-down topology accepts a wide 4.4V to 40V input, with the synchronous architecture enabling charging efficiency up to 94% as well as low dropout start-up and operation. The LTC4121 features programmable charge current from 50mA to 400mA and low voltage battery preconditioning. A new charging cycle is started by a recharge function for if the battery voltage drops 2.2% below the programmed charge voltage.

To accommodate sources such as solar panels, the charger has the ability to regulate input voltage to a programmable percentage of the input open circuit voltage. If the input voltage falls below the user-defined percentage of the open circuit voltage, charge current will be automatically reduced. Even in non-ideal operating environments, this MPPT technique enables maximum power operation with a variety of high impedance input sources.

Guaranteed for operation from -40°C to 125°C in both E and I grades, safety features include a two-hour termination timer as well as NTC temperature qualified charging. Two open-drain outputs provide charge and fault status information. Housed in a 0.75mm, 16-pin, 3mm x 3mm QFN package, the device has an exposed pad for excellent thermal performance.

The charger is suited for a range of applications including handheld instruments, solar-powered devices, as well as industrial and military sensors and devices. 1,000-piece pricing starts at $2.60 each for the E grade.