ICs Offer A Range of Digital Power Control

Mar 1, 2005 12:00 PM
By David Morrison, Editor, Power Electronics Technology

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At this year's Applied Power Electronics Conference, Texas Instruments (TI) unveiled a series of digital power components designed to enhance the performance, flexibility and reliability of increasingly complex power systems. TI's Fusion Digital Power solutions consist of three complementary series of chips — UCD9K, UCD8K and UCD7K — that offer different levels of digital control to support the design of power-supply applications from the ac line to the point-of-load. These ICs enable designers to flexibly configure power designs with programmable supervisory and monitoring functions, while extending digital power control to full-loop control (see the figure).

The UCD9K ICs are digital power controllers with specialized power peripherals on-chip. These controllers can close one or more feedback loops, while providing communications and supervisory functions. Achieving up to 150-ps digital pulse-width modulation (PWM) resolution, the DSP- and microcontroller-based controllers can implement multi-phase control, nonlinear control, load-sharing and predictive failure. These functions are typically difficult to perform in full-analog designs.

The UCD9K also enhance efficiency by providing the capability and flexibility to optimize power conversion over a broad range of loads. Gate drivers are not included in these controllers. Specifications for the UCD9K's a-d converter include 12-bit resolution for accurate regulation and monitoring as well as 50-ns conversion time to achieve wide voltage-loop bandwidth and fast transient response. Up to 16 KB of Flash memory is included on-chip for storing program and data.

The UCD8K digital power PWM controllers and UCD7K digital power drivers offer digital control support by integrating key power management functions best performed by analog circuits. The UCD7K are MOSFET drivers that interface the digital power controller to the power stage. These drivers also provide programmable analog overcurrent limiting with a status flag and a 3.3-V 10-mA linear bias supply for the digital controller.

The UCD8K controllers integrate the UCD7K driver functionality with a digitally controlled analog PWM controller to close the feedback loop. These controllers offer a choice of voltage-mode control or peak-current-mode control. The UCD8K also accepts clock input from the digital controller.

The company provides design examples showing the Fusion power ICs in a variety of applications. These include a telecom rectifier, an offline power supply, a telecom brick module, and single- and multi-phase point-of-load converters.

The UCD95K and UCD91K Fusion Digital Power controllers are supported with TI's Code Composer Studio Software, an integrated development environment that reduces development time and effort. PMBus tools are also part of the company's digital power customer support. Additionally, reference designs are supported by graphical user interface and source-code examples.

Later this year, TI plans to introduce digitally controlled, power-conversion circuits to support battery-powered products such as cell phones and notebook PCs. In addition, the company is working with power supply manufacturers to offer digitally controlled plug-in power modules and quarter-bricks using the PMBus communications protocol.

TI's Fusion Digital Power chips are currently sampling with volume production for the UCD9K, UCD8K and UCD7K expected in the next six months. Pricing in quantities of 1,000 units starts at $4.95 for the UCD9K devices, $1.99 for the UCD8K controllers and $0.99 for the UCD7K family. For additional information, see www.ti.com/digitalpower.