Maxim DS2784 - Industry's Smallest 1-Cell, Stand-Alone Fuel Gauge to Integrate an Li+ Protector and SHA-1 Authentication

SUNNYVALE, CA¡ªAugust 8, 2007¡ªMaxim Integrated Products (NASDAQ: MXIM) introduces the DS2784, the industry's first 1-cell, stand-alone fuel gauge to integrate a 1-cell Li+ protector and SHA-1 authentication in a tiny, 3mm x 5mm TDFN package. Previously, three separate ICs would have been required to give the same functionality that the DS2784 provides. Small enough to fit on the side of a prismatic battery cell, the DS2784 is ideal for space-sensitive portable applications that use 1-cell Li+ battery packs, including mid-/high-end phones, smartphones, PDAs, portable navigation/GPS devices, digital still and video cameras, and VoIP phones.

The DS2784's fuel gauge estimates available capacity based on coulomb count, discharge rate, temperature, and cell characteristics. To reduce development effort and time-to-market, it combines a precision, analog front-end for measuring current and voltage with a proven, embedded fuel-gauge algorithm. On-chip temperature measurements eliminate the need for a thermistor in the battery pack. Additionally, the DS2784 can use temperature data to enable gain and temperature-coefficient compensation in the current measurement, thereby allowing the use of a low-cost current-sense resistor.

The 1-cell Li+ protector monitors for cell overvoltage, undervoltage, overcurrent, and short-circuit conditions. Thresholds are user-programmable and can be locked to prevent accidental overwrites. The DS2784's built-in charge pump enables cell protection to be implemented with high-side n-channel FETs. This configuration maximizes battery life by reducing the R_DSON of the protection FET as the cell voltage decreases. It also allows the host system to communicate with the battery pack, even during a fault condition.

The integrated, secure challenge-response authentication algorithm provides exceptional protection against the counterfeiting of battery packs, thereby increasing safety and reliability for the end-user, as well as protecting and enhancing the reputation of the product manufacturer. It utilizes a SHA-1 algorithm with a 64-bit secret and communicates with the host over the DS2784's 1-Wire® interface.

The DS2784 enables a battery pack to meet IEEE 1725-2006 safety, identification, and authentication requirements. It is available in a lead-free, 3mm x 5mm, 14-pin TDFN package. Prices start at $2.94 (1000-up, FOB USA).

1-Wire is a registered trademark of Dallas Semiconductor Corp. Dallas Semiconductor is a wholly owned subsidiary of Maxim Integrated Products, Inc.