Data Points

Oct 1, 2004 12:00 PM

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IC Combines PoE Power Control, Power Conversion

National Semiconductor's LM5070 simplifies the design of IEEE-802.3af-compliant powered devices (PDs) for Power over Ethernet (PoE) by combining PD interface and power conversion functions in one chip. The LM5070 integrates an 80-V, 400-mA line connection switch and associated PoE interface circuits with a current-mode dc-dc controller that steps down the 48-V input to power various loads. Meant to replace existing 2- or 3-chip solutions, it comes in either an LLP-16 or TSSOP-16 package. The LM5070 combines National's strengths in analog, power management, Ethernet networks, packaging and process technologies. The chip offers user-programmable features such as undervoltage threshold and hysteresis, inrush current limiting and oscillator frequency at values up to 1 MHz. It also provides internal power sequencing of the dc-dc converter, integrating the communication between the PD interface and converter.

The part integrates the precision voltage reference and error amplifier for dc-dc feedback in nonisolated converters and provides pull-up for an optocoupler transistor in isolated designs.

More information is available at www.national.com/pf/LM/LM5070.

Ferrite Core Material

An innovative manganese-zinc ferrite material from ACME Electronics Corp. is designed to reduce power losses in high-temperature power applications. The new core material will enable development of smaller, more efficient power supplies and transformers. Designated as A041, this material exhibits optimum power loss characteristics at frequencies between 1 kHz and 100 kHz, making it ideal for LAN filters and pulse transformers with a dc-bias condition. The material features a wide working temperature range of -20°C to 100°C.

A041 ferrite material exhibits an initial permeability of 4000 ±25% at 100 kHz and 0.1 mT (25°C). In addition, saturation flux density is 1000A/m between 25°C and 100°C. The A041 material comes in many standard and custom shapes, including popular low-profile geometries.

For more information, visit www.acmemagusa.com.

Rad-Hard MOSFETs

International Rectifier's radiation-hardened logic-level MOSFETs offer a more efficient alternative to the bipolar transistors typically used in low-power rad-hard applications. The IRHLUB7970Z4 p-channel device and the IRHLUB770Z4 n-channel device may be used in place of bipolars such as the 2N2222A and the 2N2907A. Compared to the bipolars, the MOSFETs require less drive power, fewer external components and faster switching.

Packaged in 3LCC or through-hole packages, the MOSFETs are compatible with 3.3-V to 5-V TTL and CMOS logic, are rated for a 60-V breakdown voltage, and are radiation characterized to 300 krad (Si) total dose capability (TID). The MOSFETs also can withstand a single event effects, as reflected in their SEE rating to a linear energy transfer (LET) of 82 MeV (Au).

For more details, visit www.irf.com.

ACPI Specification Revised

The Advanced Configuration and Power Interface (ACPI) specification has been revised and may be downloaded from the ACPI Web site (http://acpi.info). Revision 3.0 contains general configuration enhancements along with added support for inter-processor power, performance and throttling state dependency. The revision also adds support for >256 processors, NUMA Distancing, PCI Express, SATA, and Ambient Light Sensor and User Presence device. The thermal model has been extended beyond processor-centric support.

P-Channel MOSFET Cuts R_DS(ON) in TSOP

Aimed at battery-powered applications, the AAT7357 from Advanced Analogic Technologies is a 20-V low-threshold dual P-channel power MOSFET that achieves low on-resistance thanks to a high-density TrenchDMOS process. Housed in a 3-mm × 2.85-mm TSOPJW-8 package, the transistor specifies a typical on-resistance (R_DS(ON)) of 30 mΩ at V_GS of -4.5 V. At a V_GS of -2.5V, R_DS(ON) is 49 mΩ. Until now, this level of performance has necessitated use of a TSSOP-8 package, which occupies about twice the board area of the TSOPJW-8.

For more information, visit www.analogictech.com.

Digital Power Management Protocol

Artesyn Technologies and Astec Power have formed a coalition of power supply and semiconductor manufacturers to develop and support a new communications standard defining an open architecture for power systems control.

The digital protocol, called “Power Management Bus” or PMBus, will be implemented over the industry-standard I²C serial bus. The founding group also includes IC vendors — Intersil, Microchip Technology, Texas Instruments, Volterra Semiconductor, Summit Microelectronics and Zilker Labs.

The PMbus digital protocol addresses the desire of OEM customers to have open standards that result in multi-sourced products. An open standard could allow OEM customers to continue to design their power systems using discrete components or turnkey converter solutions (dc-dc converter modules). Once the new protocol is adopted, the OEM will be able to control all compliant dc-dc converters using the same set of commands, without the need for proprietary silicon or software interfaces.

For more information, visit www.artesyn.com or www.astec.com.

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