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Tiny Sub-1µA IQ Shunt Battery System Charges & Protects Li-Ion/Polymer Batteries

17th February 2010

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Datasheet

Linear Technology introduced the LTC4070, an easy-to-use, tiny shunt battery charger system IC for Li-Ion/Polymer batteries. The LTC4070, with its 450nA operating current, charges and protects batteries from previously unusable very low current, intermittent or continuous charging sources. The LTC4070's charge current may be boosted from 50mA up to 500mA with the addition of an external PMOS shunt device. An internal thermal battery conditioner reduces the float voltage to protect Li-Ion/Polymer cells at elevated battery temperatures.

Multiple-cell battery stacks can be charged and balanced by configuring several LTC4070s in series. Housed in a low profile (0.75mm) 8-lead 2mm x 3mm DFN package, the LTC4070 provides a complete and ultra-compact charger solution with only a single external resistor required in series with the input voltage. The device's feature set is well suited for continuous and intermittent, lower power charging source applications, including Lithium-Ion/Polymer battery backup, thin film batteries, coin cell batteries, memory backup, solar-powered systems with backup, embedded automotive and energy scavenging/harvesting.

With pin-selectable settings of 4.0V, 4.1V, or 4.2V, the LTC4070's 1% accurate battery float voltage allows the user to optimize the balance between battery capacity and lifetime. Independent low battery and high battery supervisory status outputs indicate a discharged or fully charged battery. In conjunction with an external PFET in series with the load, the low battery status output enables a latch-off function that automatically disconnects the system load from the battery to protect the battery from deep discharge.