New Industry Products

TI Unveils bq2420x Family of Charge-Management ICs

September 25, 2001 by Jeff Shepard

Texas Instruments Inc. (TI, Dallas, TX) announced its new bq2420x family of single-chip charge-management ICs that enable designers to reduce heat dissipation in portable systems by more than 70 percent as compared to linear chargers, according to TI.

By integrating the charge-control MOSFET and current sensor in a small eight-pin MSOP package, the family offers a true single-chip solution, requiring only two small external capacitors for operation. Designed for use in space-limited portable applications where reducing the internal power dissipation is critical, this family is ideal for systems using single lithium-ion or lithium-polymer batteries such as wireless and Internet appliances, personal communication devices, PDAs and audio players.

The bq2420x family includes a current sensor and an internal MOSFET pass transistor, rated for up to 500mA charge applications. With this high degree of integration, designers are able to build a full battery-charger circuit using a single eight-pin MSOP package with a 15.2mm² footprint.

"The bq2420x family offers the industry’s smallest charge-management ICs, making them ideal for space-constrained applications," said Patrick Heyer, product marketing manager, TI Battery Management Products. "The family’s revolutionary new charge topology enables a significant reduction in heat dissipation, but without the cost or complexity of switch-mode or pulsing topologies."

The bq2420x family completes the charge cycle in three phases: conditioning, current-limit and constant voltage. During the conditioning phase, the bq2420x applies a gentle pre-charge current to revive a deeply discharged battery. Following this phase, the bq2420x relies on an inexpensive current-limited external power source to charge the battery. This topology removes more than 70 percent of the heat generated in the system using a similar linear charger without sacrificing safety or charge capacity.

Finally, an accurate voltage-regulation phase completes the battery charge and the internal reference is trimmed to within ±0.5 percent across the operating temperature and voltage range. In addition, the bq2420x safely terminates charge when a minimum current is reached or if the battery current fails to reach minimum voltage levels after a given time.

Samples of the bq2420x are available now with volume production planned for fourth-quarter 2001. The device is available in two fixed-voltage versions for single-cells with either coke (4.1V) or graphite (4.2V) anodes. Devices rated for higher charge currents will also be available later this year. Planned pricing for the bq2420x family starts at $1.48 in quantities of 1,000.