Wireless Systems Design

Power Converters Extend Wireless Battery Life

In mobile applications, improving power consumption is a constant concern. One way of achieving this goal is by increasing the efficiency of power converters. Texas Instruments (TI) has taken that approach with its new 1.2-A synchronous step-down DC/DC converter. By using such a device, designers of portable applications with low-power requirements should be able to increase system run times and save board space.

The TPS6204x family of step-down converters enables an extremely low quiescent current of 18 µA. The company claims that these converters offer a 95% conversion efficiency to preserve battery life in applications powered by one-cell lithium ion (Li-Ion) or three-cell nickel metal hydride (NiMH) and nickel cadmium (NiCd). Examples include wireless PDAs, smart phones, notebooks, and broadband equipment.

The converters reduce board space by integrating all necessary switching transistors. To help minimize inductor size, they operate at a fixed frequency of 1.25 MHz. In addition, the devices are available in small 3-×-5-mm, 10-pin micro-small-outline packages (MSOPs). Designers can therefore reduce board space and system cost.

The TPS6204x series manages input voltages from 2.5 to 6 V and supply output voltages as low as 0.7 V. The devices are therefore well suited to supply the ultra-low core voltage of today's low-power processors, such as TI's TMS320C5000 DSP platform.

Additional features include adjustable and fixed voltage options. A pulse-frequency-modulation (PFM)/pulse-width-modulation (PWM) mode enables high efficiency over a wide-load current range. The power converters also flaunt 100% maximum duty cycle for lowest drop-out and low-noise operation in forced, fixed-frequency PWM operation mode. At light-load current levels, a power-save-mode operation goes to work. Short-circuit detection is included as well.

The TPS6204x devices are available today in volume. In quantities of 1000, the suggested pricing is $2.09 per unit. Evaluation modules of the TPS6204x are available through power.ti.com.

Texas Instruments, Inc. Semiconductor Group
Texas Instruments, Inc., 12500 TI Blvd., Dallas, TX 75243-4136, (800) 336-5236; www.ti.com.

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