2-Cell, Fuel Gauge with FuelPack, Protector, and SHA-1 Authentication

The DS2775–DS2778 report available capacity for rechargeable lithium-ion (Li+) and Li+ polymer (Li-Poly) batteries in mAh and as a percentage of full. Safe operation is ensured by the integrated Li+ protector. The DS2776/DS2778 support SHA-1-based challenge-response authentication in addition to all other DS2775/DS2777 features.

Precision measurements of voltage, temperature, and current, along with a cell characteristics table and application parameters, are used for capacity estimation calculations. The capacity registers report a conservative estimate of the amount of charge that can be removed given the current temperature, discharge rate, stored charge, and application parameters.

The DS2775–DS2778 operate from +4.0V to +9.2V for direct integration into battery packs with two Li+ or Li- Poly cells.

In addition to nonvolatile storage for cell compensation and application parameters, the DS2775–DS2778 offer 16 bytes of EEPROM for use by the host system and/or pack manufacturer to store battery lot and date tracking information. The EEPROM can also be used for nonvolatile storage of system and/or battery usage statistics. A Maxim 1-Wire® (DS2775/DS2776) or 2-wire (DS2777/DS2778) interface provides serial communication to access measurement and capacity data registers, control registers, and user memory. The DS2776/DS2778 use the SHA-1 hash algorithm in a challenge-response pack authentication protocol for battery-pack verification.

Applications

* Digital Still, Video, and Action Cameras * Handheld Computers and Terminals * Handheld Radios * Health and Fitness Monitors * Home and Building Automation, Sensors * Medical Devices * Power Tools * Smart Batteries

* High-Side nFET Drivers and Protection Circuitry

* Precision Voltage, Temperature, and Current Measurement System

* Cell-Capacity Estimation from Coulomb Count, Discharge Rate, Temperature, and Cell Characteristics

* Estimates Cell Aging Between Learn Cycles

* Uses Low-Cost Sense Resistor

* Allows Calibration of Gain and Temperature Coefficient

* Programmable Thresholds for Overvoltage and Overcurrent

* Pack Authentication Using SHA-1 Algorithm (DS2776/DS2778)

* 32-Byte Parameter EEPROM

* 16-Byte User EEPROM

* Maxim 1-Wire Interface with 64-Bit Unique ID (DS2775/DS2776)

* 2-Wire Interface with 64-Bit Unique ID (DS2777/DS2778)

* 3mm x 5mm, 14-pin TDFN Lead-Free Package