Unique body-diode sensing improves system efficiency and cuts MOSFET voltage stress in half
Bangalore, 25 May 2015 — 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 UCD7138 low-side gate driver improve system efficiency and cut synchronous rectification MOSFET voltage stress in half compared to other digital-power solutions. For more details, see www.ti.com/UCD7138-pr.
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.
