October 8, 1998

WHAT'S HOT IN THE DESIGN COMMUNITY

USB modems sprout as vendors plant enabling chip sets

The Universal Serial Bus (USB) connector—which mysteriously appeared on PCs about a year ago and which Windows 98 now supports—opens new opportunities for peripheral design and architecture. The Pegas.usB chip set (figure) from STMicroelectronics (formerly, SGS-Thomson Microelectronics) embodies innovations that let you produce smaller, slot-saving, portable, flexible, 56-kbps (V.90) fax/ modems.

By using the host PC's CPU as the processing engine and drawing roughly 25 to 30% of the resources of a 200-MHz Pentium II, you can build a modem encompassing the ST7554 USB modem controller and STLC7550 modem analog front end. A data-access-arrangement (DAA) function supports this modem, which is no bigger than a PC "dongle" and is part of the USB modem cable. The code for this "soft modem" resides on the PC's hard disk, making the device easy to upgrade. The modem consumes less than 50 mA in operation and 500 µA in standby (approximately one-third to one-eighth the current of other slot-eating PCI modems) and is hot-connectable and plug-and-play. You can easily switch the device from PC to PC; conversely, one such modem supports different OEM PC models.

The chip set uses a conventional transformer-based DAA. However, STM intends next year to introduce a version with a transformerless, all-silicon DAA, which will be less expensive and will more easily meet worldwide public-switched-telephone-network standards with one programmable design. The Pegas.usB chip set will cost approximately $32 (OEM); a complete USB-modem bill of materials will cost approximately $40. STMicroelectronics also supplies a reference design, an evaluation board, schematics, manufacturing information, and modem and system software from Smart Link (www.smlink.com).

In contrast to the STMicroelectronics architecture, Lucent Technologies' USB-modem chip set uses an internal DSP-based, rather than a host-based processor. The 3V chip set, comprising a USB interface IC, the DSP1675 processor, and a CSP-1034C codec, evolves PCI-interface modems to USB-interface designs. The chip set costs $40 (10,000).

—by Bill Schweber

STMicroelectronics, Lexington, MA. 781-861-2650, fax 781-861-2678, www.st.com.

Lucent Technologies, Allentown, PA. www.lucent.com.

Pro-audio converter handles 96-kHz sample rates

The new Crystal CS8420 24-bit sample-rate converter targets professional-audio applications, such as audio-studio mixing boards. It works over a range of sample frequencies of 8 to 96 kHz and a conversion range of 3-to-1 to 1-to-3.It supports the AES/EBU (Audio Engineering Society/European Broadcasting Union) professional audio and S/PDIF (Sony Philips Digital Interface) consumer-audio standards. In addition to 24-bit words, the IC supports 16- or 20-bit output words. It features 120-dB dynamic range and 1117-dB total harmonic distortion. The device sells for $13.90 (1000), a price that will allow Cirrus to sell the CS8420 into consumer digital-audio applications despite its high-end specs.

—by Maury Wright

Cirrus Logic, Fremont, CA. 1-510-623-8300, www.crystal.com.

Logic family shrinks propagation delay to less than 2 nsec

To fit into today's high-speed, low-power, low-voltage designs, Texas Instruments has introduced Advanced Very-low-voltage CMOS (AVC). This next-generation logic family is the first to achieve maximum propagation delays of less than 2 nsec. Although optimized for 2.5V designs in which bus speeds are increasing beyond 100 MHz, AVC supports 3.3 and 1.8V mixed-voltage-mode systems.

AVC features a Dynamic Output Control (DOC) circuit that automatically varies the impedance of the output circuit during signal transitions to reduce noise. The DOC provides enough current to achieve high-speed transitions but quickly changes the impedance level to reduce the overshoot and undershoot noise typically in high-speed logic. AVC also eliminates the need for external discrete damping resistors and supports live board insertion into system backplanes with a power-off feature that disables device outputs.

Samples of the first four AVC logic devices will be available early in the fourth quarter of this year. Initial prices are $2.92 (1000) for the AVC16244 16-bit buffer, $2.92 for the AVC16245 16-bit transceiver, $2.92 for the AVC16373 16-bit D-type transparent latch, and $2.92 for the AVC16374 16-bit D-type flip-flop. Packaging options include TSSOP and thin very small-outline packages.

—by Warren Webb

Texas Instruments, Denver, CO. 1-800-477-8924, ext 4500, www.ti.com/sc/AVC.

Phase-change material replaces thermal grease

The Hi-Flow thermal-interface material from Bergquist is a filled polymer that you can apply to a heat sink, chassis, or heat spreader in a variety of patterns. A polka-dot pattern, for example, ensures even distribution over an irregular surface; a solid square of material is suitable for smooth surfaces. At ambient temperatures, the material remains solid. At approximately 43°C, the material flows, ensuring total wetting of the surface. The thixotropic characteristics of Hi-Flow prevent the material from flowing out of the interface; the result is a thermal interface comparable to grease but without the mess.

Hi-Flow is available as punched parts or in sheets or rolls. You can obtain it as a dry material or with thermal acrylic adhesive on one side to aid in positioning. The 0.004-in.-thick material has contact thermal resistance of 0.05-in.²/W and thermal conductivity of 1 W/m-K. The interface is rated for continuous use at 150°C. Typical applications include CPUs mounted on heat sinks, power-conversion modules, or any other spring- or clip-mount application in which you'd traditionally use thermal grease. Prices range from $0.03 to $0.04 per in.² for standard Hi-Flow on film, $0.04 to $0.05 per in.² for flexible Hi-Flow on aluminum, and $0.08 to $0.12 per in.² for Hi-Flow on a fiber-reinforced web

—by Bill Travis

Bergquist Co, Edina, MN. 1-612-835-2322, fax 1-612-835-0430, www.bergquistcompany.com.

Sensor-interface µC provides low-cost signal conditioning

The MLX90308 sensor interface provides low-cost signal conditioning for bridge-configured sensors, such as thermistors, strain gauges, load cells, and pressure sensors. The device is a dedicated 8-bit µC that contains analog- and digital-signal processing, including gain control, offset adjustment, temperature compensation, and linearity correction. Operating from a supply of 5 to 35V, the interface can provide an output of absolute voltage, relative voltage, or current. Built-in temperature compensation allows the IC to cover the -40 to +140°C industrial range. The MLX90308 stores all compensation coefficients in on-chip EEPROM, which you can easily program and reprogram using a PC with the software that comes with the IC. The interface costs $2.55 (1 million).

Melexis Inc, Webster, MA. 1-508-943-9430, fax 1-508-943-0487, www.melexis.com. 

Highly integrated PC-graphics chip sets jostle the competition

Intel is developing its first chip set, code-named "Whitney," that integrates north-bridge 2- and 3-D graphics, but two of its competitors may have beaten it to the punch. With all of the innovation going on in the PC-graphics market, the feature sets and performance capabilities of these highly integrated devices might quickly become second-rate, but the cost savings will probably still ensure them a home in low-end systems (and, perhaps, also in single-board embedded computers).

Silicon Integrated Systems (SiS) is offering samples of the SiS530 Socket 7 chip set and the SiS620 Slot 1 chip set. Both $29 (10,000) chips integrate a feature-enhanced but performance-detuned version of the company's SiS6236AGP graphics chip, specified at 800 million polygons/sec. The devices feature 64-bit local-memory and SDRAM buses operating as fast as 100 MHz, ensuring high-fill-rate bandwidth and a fast pathway to the shared system memory. The companion chip to both the SiS530 and SiS620, the SiS5595 PCI system controller, comes in a 208-pin PQFP.

Not to be outdone, Via Technologies has announced its own Socket 7 chip set, code-named "Apollo MVP4." The VT82C501 SMA $39 (10,000) north-bridge chip comes in a 492-pin BGA package and includes a 2- and 3-D graphics controller with digital-versatile-disk motion compensation. It supports a variety of main-memory types at speeds as high as 100 MHz, including NEC's Virtual Channel DRAM (see "DRAM gets to the core of the problem," EDN, Jan 1, 1998, pg 14). The VT82C501's companion chip, the VT82C686 Super south bridge, comes in a 352-pin BGA package.

Several of the other features the SiS and Via chip sets are similar, including support for three DIMM sockets, dual-channel ATA-66 IDE control, power-management and environmental monitoring, Universal Serial Bus, and super-I/O integration. Via adds AC'97 2.0 audio to its south-bridge chip, with SoundBlaster legacy support.

—by Brian Dipert

Silicon Integrated Systems Corp, Sunnyvale, CA. 1-408-730-5600, fax 1-408-730-5639, www.sis.com.tw.

Via Technologies Inc, Fremont, CA. 1-510-683-3300, fax 1-510-683-3301, www.via.com.tw.

Supply controller slashes loss, size, parts count in recharger circuits

Like the old adage about Washington spending—a billion dollars here, a billion dollars there—it soon adds up to real money: A few wasted recharger or standby circuitry watts here and there add up to significant aggregate power waste. Even if you're unconcerned about the bigger power-savings picture, you'll be interested in the latest members of the Tinyswitch (figure) family from Power Integrations, which function as the core/controller of isolated, line-operated dc supplies and can reduce consumption by 10 to 20 times. The devices can also cut size and cost for less-than-10W supplies under light- or no-load conditions.

For example, a member of the series in the external "brick" can power the ubiquitous Iomega Zip storage drive, letting you cut supply volume and weight by about 75%. You also get other benefits: Your shipping costs for supply modules also decrease. A typical power-supply design using the Tinyswitch requires fewer than 20 parts.

In operation, a supply based on the Tinyswitch TNY253, 54, and 55 yields the same energy with every cycle. The supply uses simple on/off control, rather than the more common PWM technique, and cycle skipping to achieve the desired output with insignificant switching losses that scale with power levels. A fixed current-limit operation also reduces line ripple, and high device and system bandwidths yield both fast supply turn-on with minimal overshoot and fast transient re-sponse. You can use a simple, low-turns-count transformer without an auxiliary winding for isolation, and supplies based on lower-power Tinyswitch devices need only a low-cost RC snubber for clamping.

The TNY253 operates at 44 kHz and is suitable for 2.5 and 5W supplies employing 120 or 240V-ac lines. The TNY254 operates at the same frequency and is appropriate for 5 and 8W supplies, and the TNY255 operates at 130 kHz for 7.5 and 10W supplies. You can speed your design using the vendor's reference-design board and kit and transformer-selection guide. All the ICs come in eight-pin DIP and surface-mount packages and cost 75 to 81 cents (10,000).

—by Bill Schweber

Power Integrations Inc, Sunnyvale, CA. 1-408-523-9200, fax 1-408-523-9300, www.powerint.com.

DSO offers 16M-sample memory

LeCroy's LC584AXL DSO offers memory depths that are twice those of the deepest memory scopes yet available: 4M samples/channel on four channels, 8M samples/channel on two channels, and 16M samples on one channel. Moreover, unlike some other deep-memory DSOs, the LC584AXLs full memory is usable in all trigger modes. In addition, the scope's four ADCs each take 2G samples/sec. When you use two channels, the scope interleaves the ADCs to double the sample rate to 4G samples/sec, and when you use one channel, the real-time sampling rate jumps to 8G samples/sec. That sampling rate is more than adequate for real-time capture of signals at the full 1-GHz bandwidth.

The scope's main processor is a 192-MHz PowerPC 603e. The µP's clock rate is twice that of the processors in LeCroy's earlier color DSOs. An optional jitter- and timing-analysis (JTA) package allows jitter measurements that are repeatable to 400 fsec—that's 0.4 psec.

LeCroy boasts that the LC584 series triggers on glitches and runt pulses as short as 600 psec. According to the company, the fastest competitive scopes require anomalous signals to be more than 1 nsec wide for triggering. The LC584AXL costs $39,990. The JTA package adds $1875.

—by Dan Strassberg

LeCroy Corp, Chestnut Ridge, NY. 1-800-453-2769, 1-914-425-2000, www.lecroy.com.

Beboputer prototypes, simulates, and educates

Regular EDN contributor Clive "Max" Maxfield and his partner Alvin Brown now offer a single-board implementation of the "Beboputer" microcomputer that they describe in their book Bebop Bytes Back (An Unconventional Guide to Computers). The book includes a software simulation of the theoretical microcomputer that Maxfield and Brown developed for educational purposes. The board-level implementation, "PhizzyB," also targets education, but it works equally well as a simple µP-based platform for simulation, prototyping, and even deployment of embedded applications.

To accompany the PhizzyB, Maxfield's company, Maxfield & Montrose Interactive, also developed a new version of the Beboputer simulator that includes a user interface that looks like the PhizzyB. The PhizzyB simulator comes with a variety of tools and utilities, including an assembler, a memory display, and a CPU-register display. It also includes the PBLink utility, which provides a bidirectional communications link between a host PC and the PhizzyB. The utility allows you to download programs to the PhizzyB; monitor the status; and issue control commands, such as run, step, reset, and generate an interrupt, from your PC. PBLink allows you to control a PhizzyB over a LAN or the Internet.

The PhizzyB and the new Beboputer simulator cost $199. You can order the product and several popular books from the company's Web site. Expect new hardware add-in cards and new software functions this year.

—by Maury Wright

Maxfield & Montrose Interactive, Madison, AL. 1-205-772-6648, www.maxmon.com.

Image compression catches a wavelet

Analog Device's ADV611 and ADV612 wavelet-compression chips are now in production (see "Compression puts images on a diet," EDN, June 18, 1998, pg 71). The two chips differ in their operating temperature ranges—0 to 70°C for the ADV611 and -25 to +85°C for the ADV612; the ADV612 also uses a more temperature-tolerant version of the ADV611's 120-pin TQFP. Both devices build on the compression foundation of Analog Devices' first wavelet video codecs, the ADV601 and ADV601LC.

For use in digital-video-surveillance and closed-circuit-television (CCTV) applications, the ADV611 and ADV612 add several key features. A size-programmable quality box within the video frame lets you capture fine image detail while lowering the rest of the image's contrast, thus retaining high compression rates. Motion detection retains high-frequency wavelet-luminance coefficients that compression normally discards and passes them to the system via on-chip registers for analysis. The quality box and motion detection work together to enable the video system to track an intruder or other object on the move.

The ADV611/612's edge-enhancement feature extends wavelet compression's advantage over motion JPEG with images containing wide pixel-to-pixel data variances. The ADV611 costs $18.95 (10,000); the ADV612 costs $42.95 (10,000). Analog Devices also sells a $399.95 evaluation board, an enhanced version of the ADV601's VideoPipe, which provides an audible alert when it detects motion and enables user control of quality-box position via mouse input.

—by Brian Dipert

Analog Devices Inc, Wilmington, MA. 1-781-937-1428, fax 1-781-821-4273, www.analog.com.

Compiler brews relief for embedded programmers

Many people still associate Java with bytecode, the Java virtual machine (JVM), and enormous library overhead—elements that slow program performance and increase memory requirements to unacceptable levels for most embedded applications. However, the need for increased productivity, greater code reuse, and a more user-friendly programming language has increased Java's popularity, especially for developers who want to use object-oriented programming techniques. But Java doesn't typically lend itself well to use in embedded systems for a variety of reasons. For example, Java bytecode running on a virtual machine is many times slower than native code running in C/C++. Additionally, the JVM and library support consume approximately 1Mbyte of system memory. Other Java features, such as garbage collection, make for more reliable programs but are prohibitive in a real-time application.

Diab Data now offers the FastJ compiler to help you avoid Java's shortcomings and allow you to take advantage of the Java language. First, FastJ allows you to directly convert your Java program and bytecode to binary code for MCore, PowerPC, ColdFire, and 68K processors. FastJ eliminates the need for a JVM, and the growing number of libraries in byte-code format make this bytecode-conversion feature desirable. FastJ also includes its own configurable Java libraries for java.lang, java.io, and java.util. The configurability of these libraries lets you tune them for the minimum functionality your program requires. You can use the -Xcompact compilation option to pull in stubs (.o files) that replace the actual modules in the Java libraries when your application does not require the corresponding functionality. So, when you don't need threads, properties, floating-point math, and complex string functions, you can use stubs to satisfy references to those classes or functions. You can also reduce code size by building the Java libraries themselves from the sources using macros and preprocessor directives to eliminate certain functionality.

FastJ allows you to manage memory and configure garbage collection. Java dynamically allocates memory in object constructors and then reclaims it through garbage collection; however, this reclamation can produce nondeterministic behavior because it provides no direct means of controlling when and how long the collection runs. FastJ provides a memory-"delete" feature so that programmers can programmatically manage memory, just as they can in C/C++. Although this approach eliminates the benefit of Java's automatic memory-management features, it allows you to use Java in hard real-time applications by altogether avoiding garbage collection.

For applications that can afford some nondeterminism, FastJ provides an optional, standard nonincremental garbage-collection scheme and an optional, pre-emptive, incremental scheme that will be available in a future release. The nonincremental scheme halts all tasks while reclaiming memory and may be acceptable for a variety of non-real-time functions. The pre-emptive, incremental scheme allows garbage collection to run at various priority levels so that higher priority tasks can preempt garbage collection. However, the pre-emptive incremental approach requires users to balance garbage-collection overhead with program safety because users must ensure that garbage collection is set to a sufficiently high priority level to prevent memory leaks.

Similar to Diab Data's D-CC and D-C++ compiler suites, FastJ uses a subset of the Posix standard layer to interface with low-level system functions. This allows you—with minimal programaming—to integrate FastJ with various applications and commercial RTOS packages The pSOS+ RTOS from Integrated Systems, Inc. (www.isi.com) is one of the first that FastJ will support.

FastJ works seamlessly with Diab Data's C and C++ compiler, allowing you to mix languages within your application. For debugging and program analysis, FastJ works with Diab's Real Time Analysis (RTA) suite and Software Development Systems' (www.sds.com) SingleStep debugger. Price for the FastJ compiler suite, which includes Diab Data's C/C++ compilers, starts at $2400 for a single-user, node-locked license. FastJ runs on Win9x, Windows NT, Solaris, SunOS, and HP/UX.

—by Markus Levy

Diab Data, Foster City, CA, 1-650-571-1700, www.ddi.com.

48V dc/dc converters come in maxi, mini, micro sizes

Joining Vicor's second generation of high-density dc/dc converters, 23 new 48V members target telecommunications applications. The converters have power densities of 80 to 100W/in.³. Three package sizes are available: the MaxiMOD, measuring 4.6X2.2X0.5 in. (117X56X12.7 mm) with output power of 200 to 500W; the MiniMOD, measuring 2.28X2.2X0.5 in. (68X56X12.7 mm) with output power of 100 to 250W; and the MicroMOD, measuring 2.28X1.45X0.5 in. (68X37X12.7 mm) with output power of 50 to 150W. The packages have a stepped profile that allows you to recess them into a board cutout to achieve an above-board height of only 0.43 in. (10.9 mm). The converters provide output voltages of 2, 3.3, 5, 12, 15, 24, 28, and 48V. An input-attenuator module in MicroMOD format is available to provide input filtering to meet the transient requirements of the major telecommunications agencies. Unit prices range from $200 to $235 for MaxiMOD converters, $130 to $147 for MiniMOD devices, and $95 to $112 for MicroMOD units.

—by Bill Travis

Vicor Corp, Andover, MA, 1-978-470-2900, fax 1-978-475-6715, www.vicr.com.

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