Power Hotspot

DESIGN-TEAM ORGANIZATION IS CRITICAL FOR SUCCESS: Thermal management must start with the beginning of the project. It can't be as effective if it's started further downstream in the design. Too often, initial component selection is predominantly an electrical engineering function. The packaging engineers then have to "make" it work, sometimes employing expensive solutions. THERMAL-MANAGEMENT DESIGN OPTIONS...

First, you've got ICs and power semiconductors operating at higher-than-ever power rates. Now add in the rising power densities of their associated systems and power-management devices generating more heat to support higher power loads. What you wind up with is heat dissipation reaching stratospheric levels. To keep pace, thermal management must work harder to cool these systems and maintain an operating temperature that optimizes reliability—in other words, the lower...

Hybrid technologies usually work well, providing they make the best of both the bipolar and MOSFET worlds, rather than magnify the worst. With this in mind, STMicroelectronics has developed a hybrid emitter-switched-bipolar transistor that the company says combines the strengths and eliminates the disadvantages of both technologies. Power bipolar technology typically is used in switching applications at frequencies below 70 kHz. Its low collector-emitter saturation...

We've all been taught that power factor (PF) is the ratio of real power to apparent power, or the cosine of the phase angle between sinusoidal current and voltage waveforms. When the current isn't sinusoidal (and the voltage is), PF includes a distortion factor related to total harmonic distortion (THD). Specifically, PF relates to THD by: where THD is expressed as a decimal. When the switch closes in a non-PFC boost...

Most boost converters with PFC may operate in either discontinuous mode or continuous mode. In discontinuous mode (see the figure, a), the switch is turned on when the inductor current reaches zero and turned off when the inductor current meets the desired input reference voltage. The input current stays more or less in phase with the input voltage, and the power factor is close to 1. Higher-capacity supplies run in...

The figure shows what happens to the diode in the boost converter presented in Figure 1. When the diode turns on, there's an overshoot due to the higher resistance of the n region, relative to the resistance of the n+ region. In the steady state, minority carriers reduce the resistance of the n region. But during high-speed turn-on, current increases more quickly than minority carriers can diffuse through the junction. Such...

A common element among new developments in discrete semiconductor power devices involves PFC, or power factor correction (see "Power Factor Basics," below). About 30% of the world's markets—including Europe, China, Japan, and several states in India—now require PFC in switching supplies for computing gear. Though PFC hasn't been mandated yet in the U.S., the IEEE is at work drafting standards. Stephen Oliver, who manages International Rectifier's...

Three of the driver ICs in the SiP series fit dc—dc switching power supplies, while a fourth includes a brake for brushless motor control applications. The SiP41103, SiP41104, and SiP41105 work with supply voltages from 4.5 V up to 50 V and supply drive currents up to 1 A. They switch at rates from 250 kHz to 1 MHz and exhibit a driver impedance less than 1 Ω. The SiP42101, which includes a brake function, operates at 50 kHz. All four are available now. The SiP42101 and SiP41103...

The LTC3204EDC-3.3 charge-pump doubler generates a regulated 3.3 V from two alkaline AA cells or the equivalent nickel-metal-hydride (1.8 V) source at output currents up to 50 mA. The LTC3204EDC-5 charge-pump doubler produces 5 V output from a 2.7-V lithium-ion battery input at currents up to 150 mA. Both come in a 2- by 2-mm DFN package and operate at 1.2 MHz, which allows the use of tiny external ceramic capacitors. Burst—mode operation at light loads reduces the supply current...

The PTN78 wide-input, non-isolated modules are 50% smaller than their predecessors in the PT78 family. The PTN78000, PTN78060, and PTN78020 provide resistor-adjustable 2.5 to 12.6 V and 1.5, 3, and 5 A from input voltages of 7 to 36 V. Full-load efficiency is 85% with a 5-V output. Each model is lead-free and RoHS-compliant. The PTN78000 measures 18.9 by 12.5 by 8.5 mm, the PTN78060 is 25.2 by 15.7 by 9 mm, and the PTN78020 is 37.9 by 22.1 by 9 mm. Suggested 1000-unit pricing runs $8,...

Eight small-signal, 20-V MOSFETs have their sights set on 430- to 950-mA applications, such as power load switches, power-supply converter circuits, and battery management. To protect them from electrostatic discharge, they feature integrated zener diodes on their gates. Four of these MOSFETs are p-channel devices for high-side load switching of up to 850 mA. Both single and dual modes are offered. Three are n-channel devices for low-side load switches up to 915 mA. Again, single and...

Minimizing ripple is the charge of two dual, step-down, switch-mode power-supply (SMPS) controllers with synchronous rectification for main 5/3.3-V power generation in battery-powered notebooks. They can reduce input ripple current across an input voltage range up to the 26-V maximum through fixed-frequency operation with optimal interleaving. For output current limiting, they can be used with a sense resistor, or for minimum dissipation, a lossless inductor. Housed in a 32-pin TQFN,...

To control internal loads by slowly ramping up output voltage at a desired rate, the AAT4280A intelligent switches prevent current spikes and sags in input supply rails in portable devices. The three members of the family share an extremely low-resistance p-channel MOSFET with logic-level input and level-shifting features. On-resistance is 80 mΩ(5 V) typical, and quiescent current is 25 nA. The switches operate from 1.5 to 5.5 V, and input logic levels are TTL- and CMOS-compatible....

While they're rated at 200 W, the Series 1721 dc-dc converters are designed for critical dc power applications that require the back-up/redundant features often only provided in larger dc power systems. They include two independent converters housed in a single 1.75-in. high rack-mount enclosure, with integral output OR-ing diodes for each converter. These dual-converter units can be operated from a single dc source, yet provisions also were made for dual input feeds. Users then can...

When backlighting large-panel display and dual-LCD systems, the 90% efficient CAT3606 white LED driver replaces the inductor boost circuits traditionally used in applications requiring high-brightness backlighting. A unique fractional charge-pump topology that automatically switches from 1x LDO mode to 1.5x boost mode ensures flicker-free LED current over the life of the battery. The CAT3606 also can be used to drive a main plus sub cell-phone display or a main display plus low-power...

Welcome to a Special Issue of Electronic Design focused on power. Why? For starters, power is a universal topic for all electronic design. Beyond that, on a global scale, power is at the top of environmental and political agendas due to growing demand in the developing world. Concerns about energy consumption, global warming, and greenhouse emissions are spotlighting energy efficiency, alternative energy sources, and smart power management. Efficient public transportation and...

Rising power density marks today's point-of-load (POL) dc-dc converters. Enpirion's 6-A EN5360, part of a POL product line that's already unique for integrating the inductor, achieves 700 W/in.3 More importantly from a layout perspective, it achieves 80 W/in.2 on a single-sided board. Input voltages can range from 2.375 to 5.5 V. Seven standard output voltages are pin-selectable, or any output voltage from 0.8 V to VIN can be set via a...

Some OEMs are concerned about personal liability issues. Others are confronted with the product damage caused by end users who try to power portable devices with inappropriate battery packs. A new authentication IC developed by Dallas Semiconductor may help allay those worries. The DS2703 implements a challenge/response scheme, utilizing the Secure Hash Algorithm (SHA-1) specified in the Federal Information Publication 180-1/2 and ISO/IEC 10118-3, to authenticate battery...

What is a typical application for a multifunction power-management IC? Multifunction power-management ICs are members of a new generation of devices that manage the power for special-application processors. For example, Intel's XScale processor optimizes low power consumption and high-performance processing. Its micro-architecture stateof-the-art processing technology enables it to produce mW/MIPS performance. This processor supports mobile handheld devices, including...

Advanced applications that embed 2.4-GHz 802.11b/g Wi-Fi, such as laptops, cell phones, PDAs, and Voice-over-Wi-Fi phones, have new power amplifiers at their disposal. Designed by SiGe Semiconductor, the RangeCharger RF amps feature increased integration for lower parts count and cost, smaller size, and reduced current drain for higher power efficiency. The SE2550L is a complete front-end module with all of the circuitry needed to interface the antenna and radio chip. It...