Power Electronics

Controllers Take On Complex Power Systems

Point-of-load (POL) power applications continue to inspire the development of more sophisticated power controllers with greater ability to manage power distribution and enhanced power conversion performance. In terms of the first criteria — power management — digital power controllers are making great strides by integrating the power-supply sequencing, monitoring and fault-protection functions that previously required many external components. And as one recently announced IC from Texas Instruments (TI) demonstrates, digital controllers can also allow one chip to perform the pulse width modulation (PWM) control function for multiple channels of dc-dc conversion.

Meanwhile, analog power controllers are achieving greater accuracy and faster transient response to suit the stringent demands of CPU advance in areas where analog has always had advantages. Specifically, analog core power applications. A new power controller from Intersil demonstrates such gains, while also illustrating the influence of Intel's dual core CPUs on controller development.

Exploiting DSPs

TI's just released TMS320F28044 digital signal controller exploits the computing power of a 32-bit digital signal processor with 100 MIPS of performance to manage up to 16 dc-dc converter channels using a single device. The controller targets the type of multichannel POL applications found in telecommunications and networking infrastructure equipment, servers, laptop computers and industrial equipment. At only $5 in volume, the F28044 device provides full digital loop control and system management for as little as $0.32 per channel.

The F28044 implements up to 16 channels of TI's high-resolution (HR) PWM technology, each with 150-ps resolution, and is based on the fully programmable TMS320C28x 32-bit DSP core. Also integrated into the F28044 device are a high-speed 12-bit A-D converter, 128 kbytes of flash memory, and multiple communications ports with support for the PMBus interface (see the figure).

The programmability of the F28044 controller allows designers to build intelligence into power-supply systems and simultaneously manage in real time the sequencing, margining, phase compensation and transient response of multiple dc-dc converters. The combined performance of the F28044 controller and the integrated HRPWM channels provide the full digital loop control and output accuracy necessary at switching frequencies over 1 MHz.

Samples of the F28044 controller are available today, with volume production beginning in the first quarter of 2007. For more information, see www.ti.com/f28044.

To support the F28044 controller, TI is offering the TMS320F28044 eZdsp Starter Kit (TMDXEZS28044) development platform, which is available for $495 from TI's authorized distributors and at www.ti.com/f28044ezdsp. The eZdsp kit includes hardware tools and TI's comprehensive Code Composer Studio integrated development environment (IDE) to get designers programming the F28044 quickly and easily. Along with the F28044 eZdsp, TI also offers a dc-dc module from Tier Electronics. This hardware platform, available for $295 directly from Tier at www.tierelectronics.com, is targeted for dual phase-shifted full-bridge topologies and connects easily to the F28044 eZdsp development kit.

Reporting Dissipation More Accurately

Intersil recently introduced a family of core controllers to meet the power requirements of Intel's next-generation (Core Duo and Core 2 Duo) mobile platform. These devices — the ISL6260C, ISL6261A and ISL6262A — offer improved accuracy in power dissipation reporting and achieve fast transient response and high efficiency using the company's R3 (Robust Ripple Regulator) technology.

These core controllers report the CPU power consumption through a highly accurate continuous analog output signal. Compared with conventional controllers, Intersil's R3 controllers stabilize current flow and allow less time between wave peaks in a regulator circuit.

“The ability to report power dissipation to the CPU is an important step towards optimizing the operation of the CPU and enhancing overall efficiency and battery usage, as well as overall system thermal performance,” says Majid Kafi, director of Intersil's Notebook Power products group. “Intersil's new family of controllers also offers flexible solutions for customers who are transitioning from Intel Napa platforms to the Santa Rosa platform. They can use their similar layout and still have the improved performance that our new controllers offer.”

“Improved efficiency and faster transient response,” Kafi explains, “will result from being able to use higher tolerance inductors in dc resistance measurement settings and reduce the total cost.”

To boost battery life, the ISL6260C, ISL6261A and ISL6262A support DPRSLRVR (deeper sleep) functions and maximize efficiency by automatically changing operation modes. At heavy loads in the active mode, these controllers command the continuous-conduction mode operation. When the CPU enters a deeper sleep mode, the controllers enable diode emulation to maximize the efficiency at light loads.

The ISL6260C multiphase controller implements a 3-phase power solution, but requires an external gate driver such as the ISL6208. The ISL6262A has two integrated drivers and powers CPUs at up to 44 A. The ISL6260C and ISL6262A are also able to add and drop phases for improved efficiency and flexibility. The ISL6261A offers single-phase operation with an internal driver for low-voltage/ultralow-voltage applications up to 25 A of CPU current.

Other features include enhanced load line accuracy; 0.5% system accuracy over temperature; user-programmable switching frequency; and a 7-bit VID input. The controllers also support multiple current sensing techniques, perform remote voltage sensing differentially, and provide a CPU power monitor.

The ISL6260C is available now in a 40-lead, 6-mm × 6-mm QFN and is priced at $3.25 each. The ISL6261A is available now in a 40-lead, 6-mm × 6-mm QFN or 48-lead, 7-mm × 7-mm QFN and is priced at $3.50 each. The ISL6262A is available now in a 48-lead, 7-mm × 7-mm QFN and is priced at $3.75 each. All prices are in 1000-unit quantities. For more information, see www.intersil.com.

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