Charger chips manage two sources

The LTC4075 and LTC4075X are stand-alone dual-input linear battery chargers that efficiently manage charging single-cell Li-ion batteries from two separate power sources.

New from Linear Technology, the LTC4075 and LTC4075X are stand-alone dual-input linear battery chargers that efficiently manage charging single-cell Li-ion batteries from two separate power sources: a wall adapter and USB.

Using a constant-current/constant-voltage algorithm, the chargers can deliver up to 950mA of charge current from a wall adapter supply, or up to 500mA of charge current from a USB supply while automatically sensing the presence of voltage at each input.

The final float voltage accuracy is +/-0.6% in either case.

The LTC4075X disables the trickle charge function, benefiting systems requiring more charge current during low battery conditions.

Applications include PDAs, MP3 players, lightweight portable medical and test equipment and large colour screen cellphones.

The LTC4075/X is equipped with a patented thermal regulation scheme, which maximises the charging rate without the risk of overheating.

The device is extremely flexible as each of the following is programmable via a single resistor: wall adapter supply charge current, USB supply charge current and charge termination current.

As a stand-alone charger, it also features trickle charge for battery pre-conditioning, undervoltage lockout, automatic recharge, a charge status indicator, and "power present" status outputs to indicate the presence of wall adapter or USB power.

The LTC4075/X is offered in a low profile (0.75mm) 10-lead 3 x 3mm DFN package.

The total solution footprint is less than 25mm2 as no external MOSFET, sense resistor or blocking diode are required.

To preserve battery energy, the LTC4075 draws less then 6uA from the battery terminal in standby and less then 2uA in shutdown mode.

The LTC4075/X is rated for operation from -40 to +85C.

1000-piece pricing for the LTC4075/XEDD begins at $1.88 each.

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