Power Electronics

Dual Input Charger IC Maximizes Reliability, Reduces Footprint

Advanced Analogic Technologies Inc. (AnalogicTech) announced the AAT3691, a dual input battery charger IC with integrated over-voltage protection (OVP) up to 28V. Designed to meet industry requirements for highly flexible and reliable battery charging from multiple sources, the new 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 which 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 < 1 µs.

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 m? max. Automatic charge selection circuitry recognizes the best charging source in terms of input voltage and other criteria and modifies the charge path to maximize charging efficiency. minimize charge time.

The AAT3691 also features a no battery present input (NOBAT) detection function which 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 new 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.

The AAT3691 is qualified across the -40º C to +85º C temperature range. It is available in a 16-pin 3 x 4-mm TDFN package. It sells for $1.12 in 1K quantities.
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