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LTC4070 - Li-Ion/Polymer Shunt Battery Charger System

The LTC®4070 allows simple charging of Li-Ion/Polymer batteries from very low current, intermittent or continuous charging sources. The 450nA to 50mA operating current makes charging possible from previously unusable sources. With the addition of an external pass device, shunt current may be boosted to 500mA. Stacked cell high voltage battery packs are inherently balanced with shunt charging. With its low operating current, the LTC4070 is well suited to charge thin film batteries in energy harvesting applications where charging sources may be intermittent or very low power. The unique architecture of the LTC4070 allows for an extremely simple battery charger solution; requiring just one external resistor.

The LTC4070 offers a pin selectable float voltage with 1% accuracy across the full range of operating temperature and shunt current. The integrated thermal battery qualifier extends battery lifetime and improves reliability by automatically reducing the battery float voltage at NTC thermistor temperatures above 40°C. The LTC4070 also provides both low and high battery status outputs. For applications requiring pack protection, see LTC4071.

The device is offered in two thermally enhanced packages, a compact low profile (0.75mm) 8-lead (2mm x 3mm) DFN and an 8-lead MSOP package.

Features Low Operating Current (450nA) 1% Float Voltage Accuracy Over Full Temperature and Shunt Current Range 50mA Maximum Internal Shunt Current (500mA with External PFET) Pin Selectable Float Voltage Options: 4.0V, 4.1V, 4.2V Ultralow Power Pulsed NTC Float Conditioning for Li-Ion/Polymer Protection Suitable for Intermittent, Continuous and Very Low Power Charging Sources Low and High Battery Status Outputs Simple Low Voltage Load Disconnect Application Thermally Enhanced, Low Profile (0.75mm) 8-Lead (2mm x 3mm) DFN and MSOP Packages Typical Application

Applications Low Power Li-Ion/Polymer Battery Back-Up Solar Power Systems with Back-Up Memory Back-Up Embedded Automotive Thin Film Batteries Energy Scavenging/Harvesting Packaging

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