Power Electronics

Alliance Creates Dual Sources for Digital Power Controllers

An alliance with Primarion (www.primarion.com) will enable Linear Technology (www.linear.com) to second source Primarion’s digital point-of-load (POL) power controllers. As a first step, Linear Technology will offer the LTC7510, a second source version of Primarion’s Di-POL PX7510, which includes a PMBus interface. The Milpitas, California-based chip vendor will also provide versions of all digital POL products produced by Primarion going forward. However, the agreement between the two vendors does not cover Primarion’s voltage regulator (VR) products for CPU power.

"This alliance moves digital power management toward mainstream application by ensuring that customers have dual sources for this flexible digital power solution,” says Ron Van Dell, President and CEO of Primarion. “Our Di-POL products are at the leading edge in delivering the full value of integrated digital power management. We are excited to partner with Linear Technology to jointly advance the application of digital power solutions to an expanding group of high-volume infrastructure customers."

With this agreement, Linear Technology joins the likes of Texas Instruments and Intersil, large IC manufacturers who have added digital power controllers to their existing portfolios of analog power controllers. However, in Linear’s case, the move may strike some as surprising given that the company has taken the position that the existing analog power controllers outperform the new digital power controllers.1

However, Don Paulus, VP and general manager of power products at Linear Technology,
explains that its offering of digital power controllers is “not an endorsement that digital feedback is the new way” to implement power conversion. “It [digital power] is still about power management,” says Paulus who explains that the value of the digital power controllers lies in their ability to control, configure, and monitor power system parameters.

“Our analog solutions are still superior in terms of power conversion,” says Paulus. “However, the infrastructure customer base is increasingly interested in configuring their power systems without hardware changes and in getting information from the power system.” Digital power controllers like the ‘7510 simplify this type of system-level control through their implementation of the PMBus, which is gaining support as an industry standard communications protocol for power. Linear Technology joined the PMBus consortium last year.

Paulus also notes that Linear already has a number of products that provide digital control and monitoring. Therefore, adding controllers like the ‘7510—which marry PMBus-compatible digital capabilities with the dc-dc controller—are simply expanding a product portfolio that already offers parts such as the LTC2970 for digital control and monitoring of analog power supplies.

ICs such as the PX7510/LTC7510 are general purpose POL controllers targeting applications in the networking, computing and telecommunications infrastructure markets. Inclusion of the PMBus interface on these controllers enables system-level communications with multiple POL converters for programming and monitoring of complex power systems. The Di-POL controller ICs provide seamless power management in high availability systems, enabling real-time programming and monitoring of key parameters to optimize performance and maximize system uptime.

The PX7510 and LTC7510 are single-phase, step-down dc-dc controllers that provide for outputs down to 0.7 V. A digital feedback control loop, combined with calibrated analog functions, provides a flexible, high-performance solution. The industry-standard PMBus interface is used to implement all control functions via on-chip non-volatile memory.2

Although Linear Technology has its own fabs, both Linear and Primarion will work with common foundry vendors to produce the ‘7510. For Linear, this means purchasing wafers from a foundry with which it already has a working relationship. In addition, the ‘7510 will be produced in the same CMOS process that’s used to produce Linear’s high-speed A-D converters.

Both the PX7510 and LTC7510 will be packaged in 5-mm x 5-mm QFNs with the exposed die attach pad. In terms of pc board layout, the two versions of the ‘7510 will be compatible. However, because Linear and Primarion will be using different assembly vendors for packaging the die, there will be slight mechanical differences in the two components. Consequently, a switch from one version of the ‘7510 to the other may require a change in solder stencil.

While Primarion is currently sampling the PX7510, Linear Technology expects to begin sampling the LTC7510 next month. Linear plans to ramp up production of this controller in the third quarter. Besides offering the chip, inear will support its digital POL controllers with reference designs, software, and development kits. These support tools will include those developed in collaboration with Primarion as well as those Linear develops on its own.

1. Digital Power Is Mostly Analog by Steve Pietkiewicz, General Manager, Power Products, Linear Technology, Power Electronics Technology, January 2006, page 64., available online at http://powerelectronics.com/power_digital_power_mostly/index.html .

2. For more on the PX7510, see “Power Controllers Promise Digital Benefits at Analog Prices”, online at http://powerelectronics.com/mag/power_data_points_61/index.html .)

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