Power Electronics

Digital Power Chipset Intelligently Optimizes Dead Time

Texas Instruments (TI) introduced the first power management chipset with intelligent digital control and a unique body-diode sensing feature to optimize secondary-side synchronous rectification in next-generation AC/DC and isolated DC/DC power supplies. The UCD3138A digital controller and  low-side gate driver improve system efficiency and cut synchronous rectification MOSFET voltage stress in half compared to other digital-power solutions.

Accurate control of dead time in the synchronous rectifiers helps minimize power losses and reduces the risk of MOSFET failure. The UCD3138A and UCD7138 chipset use body-diode voltage information in fast digital control algorithms to dynamically optimize dead-time and compensate for power-stage component variations without calibration or screening during mass production. This helps telecom and server end-equipment manufacturers more easily bring to market energy-efficient 80 PLUS Titanium-grade power supplies, which saves energy costs to information technology service providers.

Key features and benefits of the UCD3138A and UCD7138:

  • Intelligent diode voltage sensing optimizes dead time: Adjusting timing for minimal diode conduction increases efficiency and reliability, while eliminating the signal-to-noise ratio challenges of traditional MOSFET VDS(ON) sensing devices.
  • High peak current supports wide load range: The UCD7138's asymmetrical, rail-to-rail 4-A source and 6-A sink peak-current drive supports load range of a few-hundred watts to a kilowatt where multiple paralleled FETs are used.
  • Compact solution enables fast, efficient switching: A 3-mm by 3-mm QFN package reduces board space as well as parasitic inductances when placed alongside the synchronous rectifier MOSFETs.
  • Efficient operation at frequencies up to 2 MHz: The hardware peripherals in the UCD3138A along with 14-ns propagation delays and fast rise/fall times with minimized tolerances in UCD7138 enable extremely high frequencies.

Along with this chipset, TI has also recently released a new solution for lower-power AC/DC flyback converters. TI's UCC24630 synchronous rectifier controller delivers the highest efficiency with low sensitivity to board layout and MOSFET package parasitics. Auto low-power detection and 110-uA standby current also allow designers to easily achieve ultra-low standby power consumption.

Designers can quickly develop and debug applications with TI's Code Composer Studio™ (CCS) integrated development environment (IDE) or refer to the TI Designs 340W digital controlled LLC resonant half-bridge DC/DC power conversion reference design.

The UCD3138A and UCD7138 devices are available now in the TI store and through the company's authorized distribution network. The UCD7138 MOSFET driver is packaged in a 6-pin QFN package and is priced at US$1.10 in 1,000-unit quantities. The UCD3138A digital controller is packaged in a 40-pin QFN package and is priced at US$3.22 in 1,000-unit quantities.

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