Power manager for batteries in portable devices

Linear Technology has introduced the LTC4098-3.6 for one-cell Lithium Iron Phosphate (LiFePO4) batteries used in portable devices.

The autonomous high-efficiency power manager, ideal diode controller and battery charger specifically targets industrial meters, media players, digital cameras, PDAs, personal navigators, and especially high-peak-power and safety critical equipment.

The LTC4098-3.6's switching topology features Powerpath control, which manages power distribution from multiple sources, including 5V wall adapter, USB and a Lifepo4 battery, while preferentially providing power to the system load.

For automotive and other high-voltage applications, the LTC4098-3.6 can interface with a Linear Technology external switching regulator to provide a high-efficiency, high-voltage power path.

The onboard switching regulator can automatically limit its input current for USB compatibility.

Both the low-voltage input and the high-voltage interface feature Bat-Track optimised charging to provide maximum power to the application and reduced heat in high-power-density applications with input supplies from 5V to as high as 38V (60V maximum).

The LTC4098-3.6 provides an overvoltage protection (OVP) circuit up to 66V on the low-voltage input, requiring only an external NFET/resistor combination - preventing damage caused by accidental application of high voltage.

The LTC4098-3.6's 'instant-on' operation ensures system load power at plug-in, even with a fully discharged battery.

Its onboard ideal diode guarantees that ample power is always available to VOUT, even if there is insufficient power at the input.

The LTC4098-3.6's ideal diode controller can be used to drive the gate of an optional PFET, reducing impedance to the battery to 30mOhm or less.

The LTC4098-3.6's full-featured single-cell Lifepo4 battery charger has a preset 3.6V charge voltage with accuracy of 0.5 per cent.

Charge current of 1.5A is available when wall powered but, when connected to a USB power supply, the device allows the load current to exceed the current drawn from the USB port, while conforming to USB load specifications.

For fast charging, the IC's switching input stage converts nearly all of the 2.5W available from USB to system current, enabling up to 700mA from a 500mA limited USB port.

The charger includes thermal limiting, automatic recharge, stand-alone operation with automatic charge termination and fixed one-hour safety timer, bad battery cell detection and a thermistor input for 0 to 60C temperature-qualified charging.

An additional feature of the IC is a suspend LDO that helps to prevent battery drain when a device is connected to a suspended USB port.

The LTC4098-3.6 is housed in a 0.75mm 20-pin 3 x 4mm QFN package and is guaranteed for operation from -40 to 85C.

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