The DS2784 operates from 2.5V to 4.6V for integration in battery packs using a single lithium-ion (Li+) or Li+ polymer cell. Available capacity is reported in mAh and as a percentage. Safe operation is ensured with the included Li+ protection function and SHA-1-based challenge-response authentication. Precision measurements of voltage, temperature, and current, along with cell characteristics and application parameters are used to estimate capacity. The available capacity registers report a conservative estimate of the amount of charge that can be removed given the current temperature and discharge rate. In addition to the nonvolatile (NV) storage for cell compensation and application parameters, 16 bytes of EEPROM memory is made available for the exclusive use of the host system and/or pack manufacturer. This facilitates battery lot and date tracking or NV storage of system or battery usage statistics. A 1-Wire interface provides serial communication at 16kbps or 143kbps to access data registers, control registers, and user memory. Additionally, 1-Wire communication enables challenge-response pack authentication using SHA-1 as the hash algorithm in a hash-based message authentication code (HMAC) authentication protocol.
Precision Voltage, Temperature, and Current Measurement System
Available Capacity Estimated from Coulomb Count, Discharge Rate, Temperature, and Cell Characteristics
Estimates Cell Aging Using Learn Cycles
Uses Low-Cost Sense Resistor
Allows for Calibration of Gain and Temperature Coefficient