Electronic Design

Cooling Devices

Fan Speed Controller Features A Two-Wire Interface
Linear Technology Corp.
(800) 4-LINEAR; fax (408) 434-6441; www.linear-tech.com

The LTC1840 is a dual-fan speed controller with a two-wire interface for network servers, desktop PCs, or other high-efficiency applications where a separate dc-dc converter drives each fan. It includes two 8-bit digital-to-analog converters (DACs) with full-scale output of 100 µA. It sinks current from the feedback nodes of the dc-dc converters controlling the voltage to each fan.

This device reads the tachometer outputs from each fan to provide feedback to the processor over an I2C or SMBus-compatible two-wire bus. The LTC1840 allows the system to turn the fans on in the event of a loss of communication. The first method uses an access timer for the serial interface. A disable feature provides a failsafe setting if the bus becomes locked. A second method uses a single-pin BLAST feature to force both fans to full speed. Four general-purpose I/Os are available to drive LEDs.

The LTC1840 is available in the narrow 16-pin SSOP. It is specified for both the commercial and industrial temperature ranges. In 1000-unit quantities, pricing starts at $2.75 each.

Cross-Flow Heat Exchangers Suit Custom Applications
(717) 569-6551; fax (717) 569-8424; www.thermacore.com

The HXc line of high-performance heat exchangers is specified for custom applications with heat-dissipation requirements of 1500 W and above. These high-performance cross-flow devices effectively provide large-scale/high-power enclosure cooling for communications and industrial applications.

This line includes six base models, including the HXc-1500, the HXc-1800, the HXc-2000, the HXc-2250, the HXc-2500, and the HXc3000. The HXc-3000 achieves a thermal performance of 107 W/°C. The high-performance HXc-3000 version boasts 213 W/°C. The cross-flow system is constructed from aluminum with optional epoxy-coated plates. It's designed for high efficiency while occupying minimum space. The units are easily customizable for today's OEM applications. They can be equipped with alarms, heaters, and temperature controls. They can be manufactured to meet Bellcore GR-487-CORE and NEMA 4 and 12 (IP 55 and IP 66) requirements.

For pricing and availability, contact the company.

DC-DC Converter Heatsinks Employ Custom Arched Radial Base
(877) 334-7332; fax (673) 672-9565; www.degreec.com

High-performance Tortoise Back heatsinks suit dc-dc converters used in communications applications. This heatsink technology uses a custom arched radial base. Custom fin configurations and footprints are available to meet individual performance specifications. A crosscut enables optimal thermal performance. According to the company, these heatsinks address the thermal-management issues that the communications industry currently faces.

The Tortoise Back heatsinks are now available. For pricing information, contact the company.

Web-Based Thermal-Model Generator Speeds The Design Process
(508) 357-2012; fax (508) 357-2013; www.flomerics.com

Flopack Version 2.2 is a Web-based thermal-model generator used to generate thermal models of IC packages and associated parts with a minimum of effort. It is designed for use with the company's Flotherm thermal management software. It features Delphi compact models for plastic quad flat pack (PQFP) and plastic leaded chip carrier (PLCC) package families.

The generator features support for multiple heat sources. SmartPart Wizards are included for ChipArray-TM fine-pitch plastic ball grid array (FPBGA) and leadless leadframe package (LLP-TM) families. All detailed and compact models automatically include a monitor joint for junction temperatures. A new server hosts this Web-based resource. It offers design engineers improved access speeds and enhanced security features that safeguard valuable data. Flotherm models of voltage-regulator components can now also be imported from National Semiconductor's Web site at http://power.national.com.

Annual licenses for Flopack start at $3500 (or 100 runs).

Direct-Drive Blower Motors Target Air Conditioner Applications
Invensys Motor Systems
(800) 325-8313; fax (800) 352-7207; www.fasco.com

A line of six 5.6-in. diameter direct-drive blower motors targets furnace and air conditioner applications. The blower motors are available as either 115-V or 208- to 230-V units. Models D1703 (1/4 hp), D1704 (1/3 hp), and D1705 (1/2 hp) are 115-V units. The 208- to 230-V units include D1706 (1/4 hp), D1707 (1/3 hp), and D1708 (1/2 hp).

All models are 1075-rpm units. The standard dimension size is 8 by 0.5 by 8 in. The devices are categorized as permanent split capacitor (PSC), totally enclosed, air-over units. All models are thermally protected. They feature CSA certification and UL recognition.

For pricing and availability, contact the company.

Fan Controllers Fit Hydrostatic Fan-Drive Systems
Axiomatic Technologies Corp.
(905) 602-9270; www.axiomatic.com

Members of a family of fan controllers are designed for the electronic control of hydrostatic fan-drive systems. Variable control of the rotational speed of a fan-drive motor provides maximum efficiency and noise control for operation of the engine cooling fan system. The controllers suit applications like motor vehicles, agricultural equipment, construction equipment, and stationary power plants.

The controller accepts multiple temperature sensor and digital inputs. It interfaces to a proportional relief valve. The controller is packaged in an encapsulated metal box for the rugged mobile environment. A variety of OEM packaging and connection styles are available. The operating-temperature range of the controller is from −40°C to 120°C. Rugged vehicle power supply input includes 12 and 24 V dc. The controller interfaces to many commercially available linear and nonlinear sensors. Proportional control occurs when the temperature sensor inputs fall within the minimum and maximum temperature setpoints of the controller. While the maximum dc current output of the fan is 1.3 A (at 24 V) or 2 A (at 12 V dc), overcurrent protection is provided.

For pricing and availability information, contact the company.

Thermal-Interface Material Provides Fast Cure And High Bond Strength
Thermoset, Lord Chemical Products
(781) 337-6075; www.thermoset.com

MT-125 is a fast-cure, high bond-strength adhesive. It features a bulk thermal conductivity of 2.3 Wm/°C and can be quickly cured in five to seven minutes at 150°C. At 125°C, the adhesive cures in 15 to 20 minutes. This material features a low CTE of 28 ppm (Alpha 1) and a Tg of 129°C.

Due to its low CTE, MT-125 can help alleviate thermal mismatches between various interfaces. It improves temperature cycling and temperature shock performance. The adhesive offers a pot life of two weeks at 25°C. It's engineered to dispense easily using automated equipment. It's suited for bonding heatsinks, fan sinks, and thermal electric cools to ceramic, plastic, and metal packages.

Contact the company for pricing and availability information.

Electronic Enclosure Air Conditioners Include No Visible Hardware
Kooltronic Inc.
(800) 321-KOOL; www.kooltronic.com

The Advantage aesthetically designed electronics enclosure air conditioners feature smoothly contoured cabinets. With plastic trim, they have no visible hardware. A textured baked-powder finish is included. The series offers a standard line of indoor/outdoor NEMA 3R-rated air conditioners. They include ergonomic features as well as easy fit and operation in a variety of electronics enclosure environments.

All models provide convenient access to internal components. External LED displays ensure easy reading. Environmentally friendly refrigerants and accessories are offered. These units can be based indoors or outdoors right out of the box. No weather hoods are required. The Advantage series air conditioners are available in capacities ranging from 2000 to 24,000 BTU/H. Seven heights are offered. All models utilize the company's M/TAB integral mounting system. Also, all units are UL/CUL recognized.

For pricing and availability information, contact the company.

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