Charger system targets li-ion/polymer batteries

Linear Technology has introduced the LTC4070, a small-shunt battery-charger system IC for li-ion/polymer batteries.

The device's feature set is 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.

The LTC4070, with its 450nA operating current, charges and protects batteries from previously unusable very low current, intermittent or continuous charging sources.

Its charge current may be boosted from 50 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 0.75mm eight-lead 2 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.

With pin-selectable settings of 4, 4.1 or 4.2V, the LTC4070's one-per-cent-accurate battery float voltage allows the user to optimise the balance between battery capacity and lifetime.

Independent low- 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 it from deep discharge.

The LTC4070 is also offered in an eight-lead MSOP package.

The devices are rated for operation from -40 to 125C.

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