Power Electronics

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Power Controllers Promise Digital Benefits at Analog Prices

Primarion has launched a family of general-purpose, digital power-conversion and power-management ICs that are priced competitively with existing analog solutions. The first member of the Di-POL family is the PX7510, a power-conversion and power-management IC for nonisolated dc-dc converters in telecom, datacom, computing and storage markets. This digital-control IC uses PMBus and on-chip, nonvolatile memory (NVM) for extensive control and real-time system monitoring.

The PX7510 implements all control functions digitally, enabling adaptable and flexible power-converter designs. Using the I2C PMBus serial interface for control and monitoring, Primarion enables the power supply designer to quickly optimize designs and monitor real-time system performance. The controller works with external gate drivers and power MOSFETs to complete the dc-dc converter design.

Priced at $1.75 each in quantities of 1000, the PX7510 is less expensive than many digital power controllers. However, the controller chip represents only about one-fifth the total cost of the converter design. With this in mind, the controller has been developed to produce a bill-of-materials cost that is comparable with existing analog power converter designs.

One of the cost-saving differences is the way Primarion's chip implements memory. Rather than using conventional EPROM, the PX7510 uses Impinj technology, which allows it to integrate a modest amount of NVM without adding steps to the chip's CMOS process flow. Another cost factor is the use of state machines to implement digital control rather than using a DSP core, which requires more die area.

Configurations for the PX7510 are easily loaded, edited and saved to NVM over the device's I2C serial interface using Primarion's graphical user interface (GUI). With configurations stored on the IC, the controller can perform real-time adjustments to the designer's previously configured settings, and thereby optimize performance without the delay of accessing outside memory storage. With other technologies, many of these functions would typically require an external microcontroller.

The PX7510 operates on a single 5-V supply, has a switching frequency range of 150 kHz to 2 MHz, is capable of current sharing, and can adapt from a single-phase to multiphase operation by synchronizing up to four controllers. Primarion has plans to introduce multiphase and multi-output versions of this controller.

PX7510 functions include comprehensive fault protection and reporting along with programmable fault behavior. In addition, the controller can start up into prebiased loads and perform margining of the output voltage over the serial interface. The PX7510 provides high accuracy through internal calibration that measures and corrects current-sense error sources upon startup. The programmable current-sense temperature compensation allows the designer to tailor the response for the best accuracy over temperature. Offered in a 32-lead QFN, the PX7510 is now sampling.

RAD-Hard LDOs Boost Efficiency in Space

International Rectifier's line of radiation-hardened (RAD-Hard), 3-A ultralow dropout voltage regulators (ULDOs) target high-reliability applications such as satellites and space-exploration vehicles. These regulators achieve a dropout voltage of just 0.4 V compared with a 1-V dropout for existing RAD-Hard regulators. This reduction in dropout voltage leads to higher efficiencies at typical output voltages such as 3.3 V, 2.5 V and 1.8 V. Featuring low noise and fast transient response, the devices are designed for point-of-load power conversion for FPGAs and DSPs.

Built using hybrid construction, the ULDOs are offered in two hermetic packages. One is a 0.690-in. × 0.820-in. 5-pin MO-078AA for through-hole assembly, and the other is a 0.750-in. × 0.750-in., eight-lead flat pack for surface-mount assembly. Both packages deliver 7.5 W at full load. These devices are meant to replace LDOs implemented using discrete components, competing RAD-Hard LDOs with higher dropout voltages, off-the-shelf LDOs with shielding added externally and dc-dc converters. In addition to offering higher efficiency than some competing solutions, the ULDOs provide remote and thermal shutdown functions as well as short-circuit protection.

The ULDOs also provide up to three times more radiation hardness than existing devices. IR's ULDOs are characterized to a single-event effect (SEE) with a linear energy transfer (LET) of 84 MeV/(mg/cm2). Furthermore, they are characterized for a total ionizing dose (TID) of up to 1 Mrad (Si) and enhanced low-dose rate sensitivity (ELDRS) of up to 500 krad (Si) per MIL-STD-883, Method 1019.6, test condition D.

Available in space-level or unscreened versions, these parts are ideal for satellites operating from near Earth orbit to deep space. Complete reports of all radiation testing are available at www.irf.com/product-info/hi-rel/radrpt.html.

Two groups of ULDOs are available. The 3.3-V input devices are available with 2.5-V or 1.8-V fixed output or an adjustable output; while the 5-V input devices have an adjustable output or a fixed 2.5-V or 3.3-V output. Output voltage accuracy is guaranteed to be within ±5% over line, load, temperature and radiation. Pricing begins at $610 each in 100-unit quantities. These components are subject to U.S. export control laws and regulations.

Power Supply Controllers Take on Next-Generation CPUs

The development of multiphase power-supply controllers continues to be shaped by the specific requirements of next-generation microprocessors, which require high levels of accuracy, reliability, small size and design flexibility. These trends are exemplified by recent introductions from Maxim Integrated Products and Linear Technology.

Multiphase controllers with on-chip, dual-phase MOSFET drivers, Maxim's MAX8809A/MAX8810A implement two-, three- or four-phase synchronous-buck-converter designs that fully comply with Intel's VRD 11/VRD10 and AMD's K8 Rev F specifications.

The MAX8809A operates as a single-chip, two-phase solution with on-chip drivers, making it suitable for power requirements up to 65 W. The controller also includes an additional pulse-width-modulated (PWM) output on chip, so that two-phase designs may be scaled up to three phases simply by adding the MAX8552 driver chip. This three-phase option enables the supply to deliver up to 90 A.

The MAX8810A also integrates a dual driver but adds two PWM outputs. So the MAX8810A can be paired with the MAX8523 dual driver to achieve a low-cost, two-chip solution for four-phase designs up to 150 A.

A selection pin allows the designer to program the controller to support three different processors, including Intel VRD10.1 and next-generation CPUs from both Intel and AMD. Unit pricing for the MAX8809A and MAX8810A starts at $2.40 and $2.50, respectively, in quantities of 1000. For details, see www.maxim-ic.com/desktop-cpu-power.

Meanwhile, Linear Technology's LTC3819 is a PolyPhase, synchronous stepdown controller with integrated MOSFET drivers and a 5-bit digital interface designed to power Sun Microsystems' newest processors. The LTC3819 offers a 45-A single-chip solution, integrating four MOSFET drivers with substantial gate-drive capability. PolyPhase operation minimizes the requirement for input and output capacitors. In addition, the LTC3819 has two power sections that accurately balance the output power between the power components.

The LTC3819's 5-bit VID code corresponds to the core voltage range of Sun's new processors. Core voltage range is from 1.025 V to 1.4125 V in 12.5-mV steps, and core current can range from 15 A to 40 A. The LTC3819 can deliver this power at up to 90% efficiency from an input-voltage source ranging from 4.5 V to 36 V.

In addition, the IC's current sensing typically provides less than 2% IOUT error between the two channels. The LTC3819 includes protection functions such as current foldback, short-circuit shutdown and an overvoltage soft latch. Housed in a 36-lead SSOP package, the controller is priced starting at $4.35 each in quantities of 1000.

Linear Technology also offers the LTC1706-63, a 5-bit VID programmer IC that adjusts the output of any 0.6-V referenced regulator to meet the 1.025-V to 1.4125-V range required by the new Sun processors. For more details, see www.linear.com.

ICs Manage Analog and Digital Power Converters

Power-One's ZM7300 series of digital power managers simultaneously controls both analog power components and the company's Z-series digital point-of-load converters (POLs). A single ZM7300 IC simultaneously controls, programs and monitors up to 32 Z-series POLs, while also controlling and monitoring four analog components, such as VRMs, linear regulators, POLs and fans.

Offered in 9-mm × 9-mm QFPs, the digital power managers are open-architecture, Z-Alliance-compatible products that communicate with host systems via industry-standard I2C interfaces to support 100-kHz and 400-kHz modes of operation. The ZM7300 devices can be purchased preprogrammed to customer requirements. Or, customers can program these devices via an IEEE 1149.1-compliant JTAG port during board assembly, or by using the wizard-driven Z-Series graphical user interface and the I2C port. The ICs also can be reprogrammed “on the fly” in the application.

Monitoring capabilities include output voltage, current and temperature for each Z-Series converter. A buffer stores this information for host-system communications, facilitating system-level monitoring and remote diagnostics. Z-Series controllers also can monitor the intermediate voltage bus, accept external interrupts and initiate crowbar protection.

Unit pricing for an eight-node controller is approximately $8.50 for a quantity of 1000 pieces. For more information, visit www.power-one.com.

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