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Digital power chipset optimises dead time automatically

Digital power chipset optimises dead time automatically

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By eeNews Europe



The UCD3138A digital controller and UCD7138 low-side gate driver improve system efficiency and claim to cut synchronous rectification MOSFET voltage stress in half compared to other digital-power solutions.

Accurate control of dead time in the synchronous rectifiers helps minimise 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 optimise dead-time and compensate for power-stage component variations without calibration or screening during mass production. This helps designers to reach the 80 PLUS Titanium-grade for power supplies, which saves energy costs to information technology service providers that employ large server arrays.

The UCD3138A and UCD7138 pairing features:

– Intelligent diode voltage sensing to optimise 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 supporting 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 to enable 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-nsec propagation delays and fast rise/fall times with minimised 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-µA standby current also allow designers to achieve ultra-low standby power consumption.

Development and debug applications is 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 UCD7138 MOSFET driver occupies a 6-pin QFN package and is priced at $1.10 (1,000). The UCD3138A in a 40-pin QFN package is $3.22 (1,000).

An application note is here.

Texas Instruments; www.ti.com/UCD7138-pr-eu

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