Step-down regulators offer highest power density, efficiency in smallest package

March 08, 2011 // By Paul Buckley
Texas Instruments Incorporated has introduced at the 2011 Applied Power Electronics Conference (APEC) what the company claims is the industry's smallest, most efficient step-down regulators with integrated FETs to support up to 25 A for telecommunications, networking and other applications.

The easy-to-use, 25-A, 14-V, TPS56221 synchronous SWIFT switcher with integrated NexFET MOSFETs achieves a power density greater than 200 W/in 3 with greater than 90-percent efficiency at high loads from a 12-V input to a 1.3-V output, delivering up to 25 A of continuous output current at 500-kHz switching frequency. The new TPS56121 15-A, 14-V synchronous switcher is three percent more efficient at 5-V input to 1.2-V output and switches twice as fast as similar 15-A products in the market.

The TPS56221 and TPS56121 come in a thermally enhanced 5-mm x 6-mm QFN package, and achieve a total solution size of 315 mm 2 - 30-percent smaller than other discrete solutions. Both devices are the first switchers to integrate TI's NexFET technology, providing increased thermal performance, protection, efficiency and reliability. The switchers offer three selectable frequencies of 300 kHz, 500 kHz and 1 MHz for design flexibility and support input voltages of 4.5 V to 14 V.

Key features and benefits of the TPS56221 and TPS56121 include:

  • High-current performance and efficiency: Provides greater than 90-percent efficiency at 25-A  and 15-A peak-load currents from an input voltage range from 4.5 V to 14 V
  • Small size and greater power density: Total solution size of 315 mm 2 minimizes footprint, while achieving a power density greater than 200W/in 3

In addition to the high-current capabilities of SWIFT converters, TI's CSD86350Q5D NexFET Power Block, which was introduced in 2010, enables highly efficient, multi-phase point-of-load designs with higher current capability. The small, 5-mm x 6-mm stacked MOSFET, in a grounded, lead-frame SON package, supports frequencies up to 1.5 MHz, reduces thermal impedance and simplifies layout. The CSD86350Q5D can achieve greater than 90-percent efficiency at 25 A, and can be combined with TI's TPS40140 stackable controller to support multi-phase designs, scalable to 50 A, 100 A and higher – while maintaining high efficiency across the load.

Availability and Pricing

The TPS56221 and TPS56121 come in