Power Electronics

New products

1.8-A Step-Down Converter

The MAX8649, a 1.8-A, synchronous, fixed-frequency, dc-dc step-down converter from Maxim Integrated Products is offered in a 4-mm2 wafer-level package (WLP). The device delivers extremely tight output-voltage accuracy by integrating a highly precise band-gap reference and by minimizing offset errors in the feedback circuit. Fully differential remote sense ensures precise regulation at the load by eliminating the resistive losses associated with PCB trace impedance.

The MAX8649 achieves an initial accuracy of ±0.5% at 1.27 V, and a total accuracy of better than ±2% overload, line, and temperature. This superior accuracy allows applications processors to run at maximum clock speed, making the MAX8649 ideal for high-performance portable handsets. Additionally, this device operates from an input supply as low as 2.5 V to support the latest generation of deep-discharge battery chemistries.

This highly flexible step-down converter features an I2C interface that allows programming of the output voltage between 750 mV and 1.38 V in 10-mV steps. The MAX8649 can operate either in fixed-frequency (3.25 MHz) PWM mode or in power-save mode. It can also be configured to operate from the internal oscillator, or it can be synchronized to an external system clock for simplifying EMI reduction.

In power-save mode, the MAX8649 employs a proprietary hysteretic PWM control scheme that reduces the effective switching frequency. The end result is a dramatic increase in light-load efficiency (80% at 10 mA), as compared to that in fixed-frequency PWM mode (21% at 10 mA).

Other features include output overvoltage and overcurrent protection, thermal shutdown, soft-start, and an ultra-low 1-µA (max) shutdown current. The MAX8649 is offered in a 2.0- × 2.0- × 0.65-mm, 16-bump WLP, and is fully specified over the -40° to 85°C extended temperature range. Prices start at $1.60 in quantities of 1,000 and higher.
Sunnyvale, CA


DC-DC LED Drivers

The LD24E series from MicroPower Direct features miniature, dc-dc LED drivers. Specifically designed to power/control high-brightness LEDs, these units feature a constant-current output, output power to 17 W, PWM dimming, and efficiency to 95%.

Five models operate from an input voltage range of 5.5 to 36 Vdc and provide constant current outputs of 300, 350, 500, 600, or 700 mA. Standard features include efficiency to 95%, short-circuit protection, and a remote on/off input. A PWM input allows digital control of LED dimming. The MTBF (per MIL HDBK 217F) of the LD24E series is greater than 2.0 Mhours.

All versions are packaged in a miniature 0.9- × 0.4-in. package with an industry standard pin-out. Each model is specified for operation over the wide industrial operating temperature range of -40° to 85°C ambient with no derating or heat-sinking required. Cooling is by free-air convection.

The LD24E series drivers provide the stable output current, wide temperature operation, very high reliability, and digital dimming control required for a wide range of lighting applications.
MicroPower Direct
Stoughton, MA


Low-Noise Chokes

SMP SINTERMETALLE Prometheus (SMP) has developed chokes for use in computed tomography. These inductive components are exceptionally quiet in operation as well as being low-loss and energy-efficient. This has been achieved with non-magnetostrictive materials that have been developed specially for use in medical equipment.

SMP developed chokes for a well-known German manufacturer of CT scanners. The inductive components are installed in so-called gradient amplifiers, which supply output voltages and currents that control the gradient coils. These encode the resonance signals for subsequent image reconstruction. The filter and mains chokes have the task of ensuring a clean sinusoidal waveform within the gradient amplifiers and must ensure a low-loss feedback of the unused energy.

A unique feature of these chokes is the non-magnetostrictive powder composites from which they are made. Developed by SMP specifically for this application, these materials allow the design of exceptionally low-noise chokes to minimize the humming noise that CT scanners generate during operation — noise that can be unsettling for the patient and make it difficult for medical personnel and patients to communicate over the intercom.

During the scan, the patient lays on a stretcher inside the scanner and the medical personnel leaves the room so as not to be frequently exposed to X-rays. To minimize the burden X-rays place on the patient's body-and shorten the length of time for which the patient has to lie still in an enclosed and unfamiliar space-CT scanners must work quickly and efficiently. SMP's energy-efficient low-loss chokes provide the performance needed to meet these requirements, and their compact design saves space in the control cabinet, which is located immediately next to the scanner itself.
Graben-Neudorf, Germany


GaN Transistor

RF MICRO Devices announced that it has qualified and released the RF3931-a 48-V, 30-W GaN unmatched transistor optimized for high-power commercial and defense applications. The RF3931 is RFMD's first GaN product to achieve full product qualification, a process through which RF products are released by the company for mass production. Shipments of the RF3931 have commenced to multiple high-power amplifier (HPA) manufacturers, and RFMD anticipates GaN shipments will increase significantly as new GaN products are introduced.

The 30-W device is part of a family of five GaN unmatched power transistors to be released for mass production over the next two quarters. Ranging from 10 to 120 W, these wide-bandwidth, unmatched-power transistors enable the development of high-efficiency HPAs for a broad range of applications, including cellular and WiMAX infrastructure, CATV, military communications, public mobile radio, and radar and radar jammers. In wireless and wireline applications, RFMD's unmatched power transistors enable “green” architectures that reduce energy costs and improve network efficiency for network operators.

RFMD's RF3931 unmatched power transistor achieves high efficiency and flat gain over a broad frequency range in a single amplifier design. The RF3931 is packaged in a hermetic, flanged ceramic package providing excellent thermal stability through the use of advanced heat sink and power dissipation technologies.
RF Micro Devices
Greensboro, NC


Green PoE/PoE+ Quad PSE Controller

THE SI345X family from Silicon Laboratories Inc. is presented as the industry's most integrated, energy-efficient quad PoE controller for power-sourcing equipment (PSE). Able to support four independent PoE (IEEE 802.3af) and PoE+ (IEEE 802.3at) PSE ports, the Si345x controllers offer real-time power measurement capabilities, energy-efficient powered-device (PD) detection and disconnect algorithms, and the industry's lowest on-resistance power FETs and sense resistors. These features enable smaller, highly energy-efficient, and lower-cost PoE/PoE+ Ethernet switches and midspans designed to power multi-radio wireless access points, industrial automation systems, VoIP phones, and building security and surveillance systems.

The recently ratified IEEE 802.3at PoE+ standard supports up to 30 W per port, enabling PoE to be deployed across more power-hungry applications. However, there is a growing need to make these applications “greener” through increased power efficiencies. Network administrators increasingly demand per-port power measurement and dynamic power allocation to maximize a network's overall power efficiency and minimize power-supply costs.

The controllers incorporate high-precision current- and voltage-monitoring capabilities to measure the power consumed by each port in real time, enabling systems to maintain tighter control of power allocation. This approach enables smaller power supplies and lower supply overhead, and gives system administrators visibility into how much power is allocated to and consumed by each port in their network.

The controllers are available in RoHS-compliant, 6- × 6-mm QFN packaging. Samples and production quantities are available now. Pricing for the Si3452/3 controllers is $3.40 in 10,000 quantities. Industrial temperature range devices are also available now. The Si3452MS8-KIT is available now and priced at $345.
Silicon Laboratories
Austin, TX


Programmable DC Supply

THE SORENSEN XG 1700 Series programmable dc supply from Ametek Programmable Power delivers 1,700 W of programmable dc output to suit test, production, laboratory, OEM, and quality assurance applications. Offered in 12 models with fully programmable output-voltage ranges from 6 to 600 V, the XG 1700 delivers a tightly regulated, low-noise, low-ripple output in both constant-voltage and constant-current modes. The device also provides two low-power auxiliary dc output channels suitable for driving control relays or powering other system accessories.

The supply's 1U package is designed for compact rack-mounting of multiple units. Up to 30 units can be configured into a one-master, multi-slave multichannel power subsystem using simple RJ-45 terminated interconnections. The unit also features a “green” sleep mode, automatically powering down when idle.

In addition to precise, digital-encoder front-panel control and simultaneous voltage and current displays, the XG 1700 includes standard RS232/RS485 and USB remote-control interfaces. It also offers optional GPIB and LXI Class C Ethernet control inputs.

Commonly used SCPI-compliant device drivers are available to support system applications. Analog control and read-back full-scale signals can be user-defined, from 0 to 2 V and 0 to 10 V in a continuously variable manner, facilitating easy substitution of the XG 1700 into existing test or process control systems.

The XG 1700 supports autonomous program sequencing with the capability to store, recall, and execute pre-programmed test routines, including the operation of the auxiliary outputs, minimizing command latency and system controller overhead and maximizing system throughput.
Ametek Programmable Power
San Diego, CA


USB 3.0 Common-Mode Choke

DESIGNED SPECIFICALLY for USB 3.0 applications, the CM01S600 common-mode choke coil from Taiyo Yuden is the presented as the first in the industry to deliver a 10-GHZ cutoff frequency. The device's 25% higher cutoff frequency is achieved through its use of a precision wire-wound structure. A higher cutoff frequency is especially necessary with the improvements in USB technology.

One of the most popular data-transfer interfaces in the world, USB is now available in a 3.0 version with speeds 10 times faster than the previous version (USB 2.0). This new version increases the data-transfer speeds between PCs and mass storage devices, including external hard-disk drives and high definition-compatible digital cameras.

Because USB 3.0 uses high-speed differential signal transmission, practical applications of it require that the resulting common-mode noise is removed. The unique construction of the CM01S600 choke coil responds to this demand. With a footprint of 1.2 × 1.0 mm and a maximum height of 0.9 mm, the common-mode choke coil is currently being produced in volume quantities, with delivery of 2 weeks ARO. The price is $0.20.
Taiyo Yuden
Schaumburg, IL


High-Efficiency PSE Controller

THE LTC4274 is a single-channel PoE controller from Linear Technology that is designed for power sourcing equipment (PSE) required to provide IEEE 802.3at (25.5 W) or proprietary higher-power levels. Next-generation PoE applications call for more power to support demanding features, while increasing power efficiency in an effort to be more “green” and reduce costs.

The LTC4274 provides up to 100 W over 4-pair Ethernet cabling, and is fully compliant with the new IEEE 802.3at PoE+ standard and backward-compatible with the prior IEEE 802.3af PoE standard. To help conserve power, the LTC4274 claims the industry's lowest heat dissipation by using low-RDS(ON) MOSFETs and 0.25-Ω sense resistors, eliminating the need for expensive heat sinks and providing a more robust PSE solution.

The LTC4274 suits a variety of PSE applications, including next-generation single-port switches, cameras, and electronic message boards. Users will appreciate the extremely low power dissipation, which makes thermal design significantly easier than designing with PSEs that integrate more fragile, normally higher-RDS(ON) MOSFETs. IEEE 802.3at powered devices (PDs) can request up to 25.5 W, responding to two-event classification from the LTC4274 and confirming that the PD is indeed a high-power device.

PD discovery is accomplished using a proprietary dual-mode, four-point detection mechanism that ensures the best immunity from false detection. Advanced power management also includes prioritized fast shutdown, 14.5-bit voltage and current readback, 8-bit programmable current limits, and 7-bit programmable overload current limits. A 1-MHz I2C interface allows a host controller to digitally configure the IC or query port readings.

The LTC4274 is offered in commercial and industrial temperature grades, and is available in an RoHS-compliant 5- × 7-mm QFN-38 package. The LTC4274 is priced starting at $4.95 each in 1,000 pieces and is available in production quantities. The LTC4274 provides an upgrade path from the IEEE 802.3af compliant LTC4263/-1.
Linear Technology
Milipitas, CA


High-Performance Hybrid Stepper Motors

MAE® BRAND Size 34 (Model HS 200) hybrid stepper motors are said to exhibit superior torque characteristics to power a wide range of industrial equipment applications. Their low detent-torque-to-holding-torque ratios serve to deliver smooth and quiet operation as well as the fine positioning capability required for microstepping.

Typical applications for these steppers include actuators, packaging machinery, pumps, and other equipment across a variety of industries. The motors are CE approved and manufactured according to EN 60034-1 specifications. UL versions are available upon request.

Their top-to-bottom insulation system, incorporating stator insulators and other components, enables the steppers to withstand internal temperatures up to 130°C. Robust design and rugged construction contribute to reliability and long service life.

These hybrid steppers include three versions with step resolutions of 1.8° (200 steps per rev) in full-step mode. Holding torques (bipolar) of 779, 1062, or 1416 oz-in can be achieved, depending on motor type. All are available in standard NEMA34 mounting configuration.

Other noteworthy features include precision-honed stators and ground rotors for tight air gap and maximum performance, single- or double-ended shaft extensions, and high-temperature grade neodymium iron bore magnets. Motors can be supplied with four leads and single- or double-ended shafts upon request and can additionally be customized with gearboxes, encoders, and other options to satisfy particular application specs.
Ametek Technical Products
Paoli, PA


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