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Dual input charger IC with integrated OVP

By integrating over-voltage protection (OVP) up to 28V for both inputs, AnalogicTech’s AAT3691 is a dual input battery charger IC designed to meet industry requirements for flexible and reliable battery charging from multiple sources. The battery charger supports inputs from both AC adapters and USB ports in applications such as mobile phones, digital still cameras and other handheld devices. The charger intelligently assesses which input source offers minimum charging time and modifies the charge path, while the integrated OVP protects the battery and system against faulty input.

The AAT3691 is designed to regulate battery charge voltage and current for 4.2V lithium-ion battery cells used in a wide variety of portable systems. As an integrated battery charger IC that combines a power device, reverse current blocking and current sensing, the device is designed to operate from AC adapter inputs and USB ports across a 3.0V to 6.75V (typical) input voltage range. To maximize safety, the AAT3691 adds integrated OVP up to 28V. The OVP block offers an extremely fast response of less than 1 microsecond. Charge current can be programmed up to 1.6A for charging via an ADP and up to 0.5A for charging via a USB port using external resistors. When ADP or USB input power exceeds 6.75V typical, an internal series switch opens preventing damage to the battery or charging circuit.

 Charging and OVP total ON resistance (RDS(ON)) for the AAT3691 is a very low 600 milliohms max. Automatic charge selection circuitry recognizes the best charging source in terms of input voltage and other criteria and modifies the charge path to minimize charge time. The AAT3691 also features a no battery present input (NOBAT) detection function that prevents input power from passing through the OVP block and suspends charging when no battery is present or a battery trace or connector is defective. The charger IC also offers a variety of other protection features to protect the charging device, the control system and the battery. Battery charging status is continually monitored for fault conditions. Safety features include thermal shutdown protection, power on reset and soft start.

 AnalogicTech is also offering a slightly modified version of the AAT3691 that provides all the features described above and adds an integrated LDO. The LDO on the AAT3695 (to be available Q2, 2009) can be used to power a transceiver or housekeeping microcontroller on a cell phone or other portable device during the charge cycle, minimize current draw from the system and shorten charge time. The AAT3691 is qualified across the -40 to +85 degrees C temperature range. It is available in a 16-pin 3 x 4mm TDFN package.