New Industry Products

BENCHMARQ bq2057 Series

October 17, 1999 by Jeff Shepard

Unitrode Corp. (Merrimack, NH) recently announced the BENCHMARQ bq2057 Series of linear lithium-ion charge management ICs for portable devices. According to Unitrode, these ICs integrate a number of advanced charge-management features into a small 8-pin package. The bq2057 features include battery conditioning, high accuracy current and voltage regulation, charge termination, charge-status indication, battery temperature monitoring, and AutoComp charge-rate compensation. The bq2057 is available in four fixed-voltage versions for single- and dual-cell battery packs with either coke or graphite anodes. The voltages include 4.1V, 4.2V, 8.2V, and 8.4V. According to Unitrode, the bq2057 implements a low-dropout precision charger capable of maintaining regulation with very low input to output voltage differential. The drop-out is typically less than 0.5V, when the bq2057 is used with an external PNP transistor or p-channel FET. During charge, the proprietary AutoComp feature is designed to optimize the charging voltage, safely compensating for internal impedance of the battery pack. This feature is designed to allow the battery to reach peak capacity in typically 30 percent less time compared to conventional methods without compromising safety or increasing the size of circuit components. The bq2057 is also designed to continuously monitor battery temperature using external thermistor and, for safety, to inhibit charge until the battery temperature is within the user-defined thresholds. Other features designed into the bq2057 include: automatic sleep mode for low power consumption; direct battery connection for simplified design; charge status output for LED or host processor interface indicating charge-in-progress, full-capacity, and fault conditions; user-programmable charge current; flexible low- or high-side current sense; and automatic battery recharge. In quantities of 25,000, pricing for the bq2057 8-pin narrow SOIC or TSSOP starts at $1.15, and pricing for the 8-pin DIP starts at $1.10. Samples are currently available.