Electronic Design

Power ICs Charge Ahead In One-Cell Li-Ion Applications

Unrelenting growth in applications powered by single-cell lithium-ion (li-ion) batteries, such as PDAs, cell phones, and digital cameras, continues to propel the development of battery-management chips. In the latest round of IC introductions, semiconductor vendors demonstrate their ongoing efforts to pack greater functionality into smaller, thermally enhanced packages. These chips accommodate standard li-ion batteries as well as newer lithium-polymer variations.

The TPS65010 power IC from Texas Instruments (www.ti.com) not only charges single li-ion cells, it also performs the major power-management functions required when multiple power rails and advanced application processors are present. This 7- by 7-mm QFN chip replaces existing discrete solutions that may occupy three times the board space.

Also, the TPS65010 integrates two synchronous step-down dc-dc converters with on-chip FETs, one 1-A converter for system voltages, and one 400-mA converter for processor cores. The IC additionally integrates two 200-mA low-dropout regulators. In keeping with a recent trend to allow battery charging from the USB, the TPS65010's 1-A linear battery charger accepts power from either the USB port or an ac adapter (see the figure). The TPS65010 costs $4.99 each in 1000-unit lots.

Another vendor, Microchip Technology (www.microchip.com), has unveiled a family of single- and dual-cell li-ion charge-management controllers. The MCP7384x devices feature a voltage-regulation accuracy of ±0.5%, improving cell utilization when compared with more loosely regulated chargers.

The chips' low current consumption (4 mA max, 0.75 mA typ.) gets even smaller when the chips automatically switch to a power-down mode (1 µA max, 0.4 µA typ). Other features include cell preconditioning, cell-temperature monitoring, advanced safety timers, automatic charge termination, and charge status indication. Available in eight- and 10-pin MSOPs, the MCP7384x starts at $1.01 each in 1000-unit lots.

Microchip also announced another IC that aims to improve cell utilization. A high-accuracy fuel gauge, the PS700 monitors cell voltage, charge and discharge currents, and temperature. Its current measurements have an error of just ±0.5%. Housed in an eight-pin TSSOP, the PS700 costs $1.45 each in 1000-unit lots.

Meanwhile, Intersil (www.intersil.com) has introduced its AnyAdapter ISL6292. This linear li-ion battery-charger IC comes in a near-chip-scale DFN package as small as 3 by 3 mm. Features include high thermal efficiency along with full voltage protection, current protection, and Intersil's Thermaguard temperature-controlled charge-rate protection. The ISL6292 accepts a range of voltage sources, including voltage and current-limited ac-dc adapters and USB power.

Charge current is resistor-programmable up to 2 A. When operated from a current-limited ac-dc adapter, the ISL6292 minimizes thermal dissipation, achieving the thermal efficiency typically found only with pulse or switching chargers. In addition to the 3- by 3-mm DFN, the charger chip is also offered in 4- by 4- and 5- by 5-mm QFNs. All are priced at $0.95 each in 1000-unit lots.

For information on related announcements including linear charge controllers from Maxim Integrated Products, Advanced Analogic Technologies, and National Semiconductor and a switchmode charger from Linear Technology, see "More Li-Ion Charger ICs" at www.elecdesign.com. For more background on single-cell li-ion ICs, see "Battery Management Chips Empower Portable Designs" Electronic Design, Feb. 17, 2003, p. 45, or ED Online 2982.

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