Charger Operates Without Mcu, Firmware Aid

An autonomous 1- to 4-cell, 0.4A to 2A linear NiMH and NiCd battery charger by Linear Technology Corp, the LTC4060, includes all the functions required for a battery charger circuit, operating without the aid of a microcontroller or firmware. The design is simple and needs only three passive components. The device eliminates the need for a sense resistor and blocking diode, which increases efficiency and lowers the solution cost.

The LTC4060 uses an external PNP transistor to supply current to the battery or battery pack. The operating voltage ranges from 4.5V to 10V. It provides three options for terminating the charge cycle: negative deltaV, maximum voltage or maximum time. The chip permits the use of a thermistor for temperature. The charge current is adjustable with a resistor and has a ±5% accuracy. The battery charger also features automatic battery detection, charge and AC present status output, pre-charge qualification, automatic recharge, reverse current protection, and manual shutdown. Battery drain current is <1µA during sleep mode.

The LTC4060 is offered in 16-lead TSSOP and 5-by-3mm DFN packaging options, and is rated for operation between -40°C and 85°C. Pricing starts at $3.80 each in 1,000-piece quantities.