Battery Charger for Extending Backup Battery Life of Automotive eCall Systems by Intersil

Highly integrated ISL78693 offers the industry’s lowest leakage current to increase eCall backup battery run-time when vehicle is off

Intersil Corporation, a leading provider of innovative power management and precision analog solutions on Jan. 17, 2017, announced the ISL78693, a 3.6V single-cell battery charger that extends the life of Lithium Iron Phosphate (LiFePO₄) batteries used in automotive emergency call (eCall) systems. The ISL78693 battery charger offers up to 4x lower leakage current (3uA) than competitive chargers, allowing the eCall backup battery to remain charged for a longer period of time. See a demonstration of the ISL78693 in Intersil’s booth #E30-11 at the Automotive World conference, January 18-20 in Tokyo, Japan.

Automakers worldwide are installing eCall in their Vehicle to Infrastructure (V2I) systems. In the event of a crash, the eCall system automatically broadcasts its location via GPS and contacts the nearest 24-hour emergency call center for help. Thus, V2I eCall systems must be capable of operating reliably and autonomously from the backup battery at a moment’s notice, even if the vehicle is involved in an accident minutes after being parked for several months.

The ISL78693 battery charger is designed to support emerging worldwide eCall systems such as Japan’s D-Call Net trial, which saves additional life-saving seconds by automatically transmitting vehicle data to an emergency call center that assesses collision severity and dispatches ground or air-ambulance help. Europe’s eCall initiative also brings immediate assistance to motorists involved in a collision, and both ERA-GLONASS in Russia and OnStar in the United States provide safety and ambulance call services.

The ISL78693’s battery temperature monitoring and low 3.6V output voltage helps safeguard and extend the life of popular LiFePO₄ batteries. The ISL78693 offers a much simpler and easier to use solution than the competition, requiring only five external passive components to program the full charging platform. The ISL78693’s tiny 3mm x 3mm DFN package easily fits on space-constrained PCBs, creating a very robust, small footprint design. It also offers a unique charge current thermal foldback feature that prevents overheating by automatically reducing the battery charging current to enhance reliability.

“Carmakers want an automotive-qualified battery charger that prevents rapid discharging of the backup battery during a traffic accident or when the vehicle is parked for an extended period of time,” said Philip Chesley, senior vice president of Precision Products at Intersil. “The ISL78693 leverages Intersil’s innovative power management technology to deliver a solution that provides the industry’s lowest leakage current and a charging profile optimized for eCall applications.”

Features and Specifications:

• Complete charger for single-cell Lithium chemistry batteries
• Reverse battery leakage of 700nA (

  typ) and 3uA (max) over -40°C to +85°C increases duration the backup battery remains charged when Vin supply is off

• Up to 1A programmable charging current, allows trade-off of battery charging time against heat dissipation and expected battery lifetime
• Guaranteed operation down to 2.65V after start-up, preventing shut off during

  cold-crankstart

• 1% initial voltage accuracy provides precise control of charging level to extend operating lifetime of battery
• Integrated power transistor and current sensor
• 10% trickle charge preconditions fully drained battery until it reaches 2.6V minimum charge level
• NTC thermistor input protects battery by monitoring temperature and shuts off charger when battery is outside the specified charging temperature
• Accepts Constant Current/Constant Voltage (CC/CV) types of voltage adapters or USB power
• AEC-Q100 Grade-3 qualified

The 3.6V ISL78693 is pin-compatible with the 4.1V ISL78692 Li-ion battery charger. Either charger can be combined with the ISL78268 55V synchronous buck controller, ISL78201 2.5A synchronous buck/boost regulator, ISL78206 2.5A synchronous buck regulator, and ISL78233 3A synchronous buck regulator to provide a full power supply solution from 12V lead acid battery to eCall battery.

Pricing and Availability
The ISL78693 battery charger is available now in a 10-pin, 3mm x 3mm DFN package and is priced at $0.99 USD in 1k quantities. An ISL78693EVAL1Z evaluation board is also available for $56 USD. For more information, please visit: www.intersil.com/products/isl78693.