December 4, 1997

WHAT'S HOT IN THE DESIGN COMMUNITY

RFID components add sophistication, features

Radio-frequency-identification (RFID) devices help solve many product tracking and identification problems. As such, they're reaching mass-market applications, including the food industry. However, the devices must meet severe size, cost, information-density, and power constraints.

Meeting those constraints are the MCRF250 and MCRF350 passive tags from Microchip Technology. The tags come with factory-preset modes for NRZ-direct, differential-biphase, or Manchester-biphase data en-coding; direct or FSK/PSK modulation; and end-user one-time programmable 96- or 128-bit data fields. They derive their power from the RF energy via an on-chip rectifier and a voltage regulator and include an anticollision protocol for use with a back-scattered EM field; the tag modulates, or loads, the field, thus reflecting information to the RFID reader. The 125-kHz MCRF250 allows the reader to resolve as many as eight tags/sec; the 13.56-MHz MCRF350 lets the reader process 25 tags/sec.

Packages for these devices range from bare die through SOIC and DIP, and you can program the tags' memory without electrical contact after their encapsulation. The MCRF250 and MCRF350 cost $0.35 and $0.45 (10,000), respectively. Microchip also offers an RFID-development and -evaluation kit to let you program and read tags and plans to offer a PC-based programmer for field use.

In a related development, SCS Corp has signed an agreement with Sainsbury's Supermarkets Ltd, a major food chain in the United Kingdom and parent company of Shaw's Supermarkets in the United States, to test the use of SCS Corp's passive Interactive Identification I² system RFID tags. The food chain will use the tags for the chilled-food supply chain, which handles 225,000 crates of prepared meals per week. The flexible-laminate tags cost less than $1 and store 1 kbit each. (See "RFID tags shrink and gain flexibility," EDN, June 19, 1997, pg 18 and "Hot 100 products" in this issue, pg 64.) Because the tags allow both read and write operation after installation, they function as traveling databases that can be scanned as many as 50 times/sec. SCS also offers a starter kit of tags, a scanning system, demonstration software, and documentation.

--by Bill Schweber

Microchip Technologies Inc, Chandler, AZ. 1-602-786-7200, fax 1-602-899-9210, www.microchip.com.

SCS Corp, San Diego, CA. 1-619-485-9196, fax 1-619-485-0561, www.scs-corp.com.

Op amp squeezes two devices into one-device package

Just when you thought op amps couldn't get smaller, Burr-Brown's OPA2337 puts a dual device into an SOT-23 package that commonly contains single op amps (see "'Good things come in small (IC) packages," EDN, Feb 3, 1997, pg 73). Using an eight-pin version of the package, you get two op amps in a footprint about 40% smaller than a standard MSOP that usually holds dual devices.

The CMOS op amps operate from a 2.5 to 5.5V supply with 450-µA quiescent current. Typical input bias current is 10 pA, and typical input offset voltage is ±1 mV, increasing to ±5 mV over the ­40 to +85ºC operating range. The output of the op amps can swing from rail to rail with 1.5-MHz gain-bandwidth product and 1V/µsec slew rate. Open-loop gain is 120 dB. The dual-channel SOT-23-8 OPA2337 costs $0.19 (OEM); a single-channel device, the OPA337, with the same electrical specifications but in an SOT-23-5 is also available.

--by Bill Schweber

Burr-Brown Corp, Tucson, AZ. 1-520-746-1111, fax 1-520-746-7401, www.burr-brown.com.

Analog drivers/transceivers boost timing
margins in 80- to 100-MHz systems

To ease the design of high-speed synchronous memory subsystems, a family of 16-bit-wide line-buffer/drivers and bidirectional transceivers for low-voltage-TTL interfaces cuts propagation delay and transfer time. Micro Linear's ML6516xxx series uses analog rather than digital drive circuitry to yield maximum propagation delay of 2.5 nsec at 5V and 2.25 nsec at 3.3V, compared with 3 nsec for digital equivalents. With 10- to 20-nsec cycle transfers, even this small saving is significant.

The 3 to 5V V_CC devices, available in 48-pin SSOPs and TSSOPs, have maximum enable and disable times of 7.5 nsec. Circuitry within the drivers and transceivers minimizes ground bounce by turning off the forward-charging circuits that charge the bus and reverting to steady-state buffers after the initial transient phase. All the ICs have three-state outputs and cost $2.90 (1000).

--by Bill Schweber

Micro Linear Corp, San Jose, CA. 1-408-433-5200, fax 1-408-432-0295, www.microlinear.com.

If a noisy noise annoys your system, try this LDO regulator

Even a few millivolts of noise can cause serious performance problems with sensitive analog and RF circuits, such as the synthesizer/VCO in a cellular phone. Maxim's MAX8867 low-dropout linear regulator strives to minimize the problem by cutting noise to just 30 µVrms and providing ±1.4%-accurate outputs in a selection of factory-preset values from 2.5 to 5V and load current as high as 150 mA.

The five-pin SOT23-packaged devices have just 165-mV dropout voltage at full load. Maximum supply current is 100 µA because of the P-channel MOSFET output; linear regulators with PNP transistor outputs, in contrast, have supply currents of milliamps at full load. When you shut down the $0.88 (1000) regulators, you reduce their supply current to less than 1 µA. In addition to short-circuit, thermal-shutdown, and reverse-polarity protection of the MAX8867, the similar MAX8868 also incorporates an autodischarge feature that actively discharges the output capacitor when the regulator is in shutdown mode.

--by Bill Schweber

Maxim Integrated Products, Sunnyvale, CA. 1-408-737-7600, fax 1-408-737-7194, www.maxim-ic.com.

Multimedia: coming to a magazine near you?

Paper as a distribution medium for computer-readable sound, videos, and other multimedia material? How's that again? It's true: The technology exists today for distributing any computer-readable material (executable software as well as data) as a pattern of dots on a printed page. The technology, a 2-D bar code, appears on a page as a "data tile"--a rectangular pattern of small dots of varying shapes and sizes like a marbled floor tile. By visiting the Web site of the publisher, Cobblestone Software, you can download a shareware version of PaperDisk, a $29 Windows 3.x and Windows 95 software package that implements the technology. If you have a Twain-compliant document scanner and an ink-jet or laser printer, you can experiment with the software for free. Unfortunately, if your scanner is not Twain-compliant, you must buy PaperDisk to find out whether the package works.

PaperDisk fits a file of almost 200 kbytes onto an 8½×11-in. page at 300 dpi. Using standard forms of data compression, including that of PKZip from PKWare (Brown Deer, WI), you can often fit files of several megabytes onto a page the size of this magazine. However, most multimedia files contain not just a few but tens or hundreds of megabytes. Whether magazines would print the multipage data tiles that such files would require depends on the willingness of advertisers to have messages appear opposite such material. Presumably, readers interested in scanning the tiles would look at the ads on the facing pages.

PaperDisk has a few blemishes. For example, if you use a large font, legends in the on-screen buttons are truncated at the window edge, so you must guess at the purpose of these buttons. However, you can usually figure out where to click. Some of the operations can take a few minutes, and PaperDisk provides no definite indication about whether it is hung up. Such operations take even longer when you're decoding a scanned image--particularly with large, high-resolution images and less-than-state-of-the-art PCs. Sometimes, the program produces error messages that suggest that a fatal error has occurred yet then recovers and completes the requested operation. At other times, the error messages suggest that you wait because waiting might be productive, yet a fatal error has occurred.

The time required to perform operations can also be frustrating. However, the speed problems I encountered were mostly not in PaperDisk but in other applications I had to use to create files that PaperDisk could accept. Because my scanner, a Hewlett-Packard (Palo Alto, CA) ScanJet 4s, is not Twain-compliant, I had to use the scanner's slick and user-friendly Visioneer (Fremont, CA) PaperPort software.

The 4s is a relatively inexpensive sheet-fed monochrome unit. Cobblestone assured me that PaperDisk's highest density data tiles require a scanner with resolution higher than that of the 4s. The company provided some tiles that work well with most flatbed scanners but would supposedly push the 4s beyond its limits. I tried a file marked "scan at 400 dpi minimum." At its highest resolution and using an 8-bit gray scale, the 4s produced a bit-map file that PaperDisk converted to text without problems. PaperDisk reported a processing error during the conversion, but it corrected that problem, and the resulting text file was error-free.

The bad news was that my 100-MHz Pentium PC with 16 Mbytes of RAM and a fast hard drive took nearly 40 minutes from the time the 4s had completed its scan until PaperPort displayed an image of the 1-pg data tile on my monitor. The PC took another 10 minutes to convert the image to an enormous file in .BMP format. BMP is one of many formats that PaperPort handles but one of only a few that Paper-Disk accepts. PaperDisk then took several minutes to convert the .BMP file to more than 700 kbytes of text. Had the scanner been Twain-compliant, the intermediate steps of producing the .BMP file and having PaperDisk read it would have been unnecessary.

I then scanned a tile marked "scan at 300 dpi minimum." For this test, I first chose a 300-dpi×1-bit setting. PaperDisk could not convert this image. PaperDisk succeeded when I got to 300 dpi×4 bits. At this rather high-resolution setting, scanning and converting to text were still much faster than at 400 dpi×8 bits. Nevertheless, at the lower resolution, PaperDisk reported and corrected more errors. I next tried scanning the same tile on EDN's fax machine and faxing the image to my PC. I saved the image as an uncompressed .TIF file. Although PaperDisk accepts .TIF files, it could not convert this image. I also tried faxing the 300-dpi×4-bit image from my PC at home to my PC at work. Whereas PaperDisk could convert the original scanned image, it could not convert the faxed version. Apparently, faxing greatly reduced the image resolution. The original uncompressed .TIF file was larger than 400 kbytes; the .TIF file I recovered from the fax was about one-tenth that size.

PaperDisk prints data tiles on dot-matrix and laser printers. I encountered no difficulty producing tiles on an HP LaserJet 4M or DeskJet 660C. One of those tiles appears as Figure 1 on the previous page. If you have a Twain-compliant scanner, download PaperDisk, scan the figure, and convert the scanned image to its original form. You may need to add a .TXT extension to the filename. This tile is fairly low-resolution and requires a 200-dpi scanner. See what you get, and let us know what kind of success you had.

--by Dan Strassberg

Cobblestone Software, Lexington, MA. 1-781-863-0035, www.paperdisk.com.

Three-IC satellite-radio-receiver
set decodes RF to baseband

SGS-Thomson's three-IC Starman provides the major functional blocks of the WorldSpace receiver. Next year, WorldSpace will begin to provide direct satellite-to-user digital radio services using three geostationary satellites covering Africa, Central and South America, and Asia. (North America is not part of the service plan.) Each satellite will broadcast at 1452 and 1492 MHz, multiplexing 96 16-kbps channels representing voice and music at various fidelity levels, plus auxiliary data services, to listeners with small dish antennas and receivers.

The Starman chip set makes WorldSpace sufficiently low cost for mass-market use. The STA001 RF front end uses the long-established superheterodyne architecture to amplify and downconvert the RF signal, still as an analog function, to 1.8 MHz. The STA002 channel decoder then demodulates the signal with an A/D converter, AGC, demultiplexers, and Viterbi/Reed-Solomon decoders, among other functions; its output is an MPEG-coded bit stream of 16 kbps for basic monaural AM to 128 kbps for stereo-CD quality. The STA003 source decoder then performs MPEG 2.5 Layer 3 decoding.

The decoded bit stream goes to a DAC, which reproduces the original audio signal. The receiver system also requires a front-end low-noise amplifier, a low-end microcontroller for IC- and user-interface management, and the requisite power-supply components and user interface.

--by Bill Schweber

SGS-Thomson Microelectronics Inc, Lincoln, MA. 1-781-259-0300, fax 1-781-259-4420, www.st.com.

Flyback regulator maintains output,
isolation without optoisolator

Using the LT1425 current-mode switching regulator, you can convert an unregulated 3 to 20V input supply into a regulated supply rail for loads as high as 6W with ±5% regulation. By using a special feedback architecture, this device requires neither an optoisolator nor an extra primary-side transformer winding to maintain input-to-output isolation, resulting in simplified design and cost savings. Typical applications are supplies for LANs, isolation amplifiers, PCMCIA cards, and telephone interfaces.

Nominal switching frequency for this regulator is 275 kHz, although you can synchronize its frequencies via an external clock from 320 to 450 kHz to minimize system interference and intermodulation artifacts. The 16-pin narrow SO device with an onboard 1.35A switch maintains its regulation specification even with discontinuous or light loads. The device requires 7-mA quiescent current, and standby current consumption drops to 20 µA in shutdown mode. The $2.90 (1000) LT1425 output voltage is resistor-programmable, and fixed-output voltage devices, such as for ­9V Ethernet applications, are also available.

--by Bill Schweber

Linear Technology Corp, Milpitas, CA. 1-408-432-1900, fax 1-408-434-6441, www.linear-tech.com.

Software automatically creates faster instrument drivers

If you've used recent versions of LabWindows/CVI to develop instrument drivers, V5.0 may not at first seem very different. But a "state-caching" technique enables the drivers that the package creates to run 1.5 times as fast as drivers that earlier versions created. Moreover, a group of "wizards," or software agents, automate writing the drivers. The computer queries you about the instrument commands, you respond, and the computer sends the commands to the instrument. You then verify that the instrument is reacting correctly. After that, the wizards take over, automatically producing drivers that, in most cases, are error-free.

Instrument drivers are software modules that stand between instrument hardware and the software packages with which you design custom applications. Writing instrument drivers has always been tedious, time-consuming, and error-prone--at least when the drivers must work in a multitude of applications. Although general-purpose drivers must support many instrument modes, generality is often the enemy of speed. In product testing, fast test execution is the key to a good return on test-development investments. The key to bulletproof operation is knowing the state of an instrument before you ask it to make a measurement. Consequently, drivers often reset instruments to a known state before each measurement. Generally, this approach means transmitting commands to the instrument, usually via IEEE-488, and waiting for the instrument to settle before sending the commands that prepare the unit for the next measurement.

To reduce such time-consuming message traffic, LabWindows/CVI V5.0's state-caching drivers store images of the instrument states within the controlling computer. This approach eliminates frequent resets to known states and queries to determine the instrument state. The technique also reduces delays for relay operation and amplifier settling. Prices for LabWindows/CVI start at $995 for PCs and $2995 for Sun SPARCstations and HP workstations.

--by Dan Strassberg

National Instruments, Austin, TX. 1-800-258-7022, fax 1-512-794-8411, info@natinst.com, www.natinst.com.

Midrange UPSs boast advanced
outlet management, low distortion

UPSs, like their offline power-supply siblings, are often an afterthought in system design. This perspective is changing, however, as they become increasingly critical to system reliability and availability. The Anzen 500-, 800-,
1100-, and 1500-VA UPS family from International Power Technologies provides basic line conditioning, backup, and outlet management.

You can instruct the Anzen UPS to selectively turn outlets on and off, thus providing longer runtime from the batteries for the more critical supported devices; you can also define startup/shutdown sequences so that attached equipment comes up and goes down in the order you require. The UPS output is regulated to ±10% of nominal, meeting the CBEMA/ITIC (Computer Business Equipment Manufacturers Association/Information Technology Industry Council) 1996 voltage-regulation standard. The UPS consumes no battery power to boost line output during brownouts. Equally critical, the UPS output waveform is a sine wave with less than 3% THD, which is purer than a quasisine or stepped wave that some systems provide.

Each UPS comes with power-management software for PCs and networks that let you locally or remotely observe and manage the supplies' operation, or you can use the built-in 20-LED user panel. This software automatically notifies you of critical changes in system and UPS operation or status. All units have hot-swappable batteries. The 500 VA unit measures 7.7×5.5×16.8 in. (195×140×427 mm) and costs $395 with a 6-minute full-load-capacity battery; larger capacity battery packs are available.

--by Bill Schweber

International Power Technologies Inc, Orem, UT. 1-801-224-4828, fax 1-801-224-5872, www.iptinc.com.

Triple driver provides muscle for large, hi-res CRTs

Those high-voltage, fast-slewing drive signals that large-screen monitors need have to come from somewhere, and a 3V IC doesn't suffice. National's LM2403 triple-channel CRT-driver IC provides the speed for "super XGA," typically 17 to 21 in. monitors, such as those for CAD and EDA applications. The three high-input-impedance, wideband amplifiers for 1 to 5V inputs, with fixed gain of ­14, directly drive CRT grids. Driver outputs are commensurate with 1600×1200-pixel monitors with 160-MHz pixel-clock frequencies and 95-kHz scanning rates.

With the LM2403 and a 60V supply, you can achieve 4.5-nsec rise and fall times with a 40V p-p output swing while driving an 8-pF load; with an 80V supply, the output can swing as high as 60V. Lowpass filtering minimizes EMI emissions, and amplifier outputs are stable with loads as wide as 20 pF and with inductive-peaking networks. The LM2403 costs $4.10 (1000) and comes in a staggered-pin TO-220 molded-plastic power package with a heat-sink tab. A reference-design schematic and board layout is available to ease CRT-neck-board design, which has numerous critical RF and high-voltage aspects.

--by Bill Schweber

National Semiconductor Corp, Santa Clara, CA. 1-408-721-5000, www.national.com.

PC-board design gets an Internet push

OrCAD has expanded its Internet-based customer assistance with the OrCAD Design Network. This new service gives you several ways to receive and access design and technical information about OrCAD pc-board-design tools.

Design Network's Internet-based parts cover proactive, reactive, and interactive communications. The proactive portion, a Push-technology-based Knowledge Channel, gives you technical support information, product-update notices, and up-to-date technology and industry news for pc-board design. The Knowledge Channel users a "tuner" that you set to prompt you when hypertext-linked information arrives. You can immediately access the information or store it in an electronic in-basket for later review, avoiding e-mail clutter.

The reactive Knowledge Base is a catalog of thousands of design questions to and answers from OrCAD technical-support engineers. Covering topics from schematic- and HDL- design entry through pc-board layout, the Knowledge Base is a convenient place to find quick answers to many technical and product-related frequently asked questions.

The interactive Knowledge Ex-change is a technical "chat room," in which you exchange ideas and information with other designers and with OrCAD technical people. In the Knowledge Exchange, you can ask questions for open discussion, go online with an OrCAD representative for discussion, search for technical information, or e-mail someone on the Exchange for a one-on-one discussion. Each time you log onto the Exchange, you get an update of what happened since your last visit.

The complete Design Network is part of OrCAD's Extended Support Option. The cost, which includes full maintenance on the associated purchased EDA tool, starts at around $200 a year, depending on the tool purchase price. OrCAD also provides a free 90-day Design Network trial with each OrCAD product you buy.

--by Jim Lipman

OrCAD, Beaverton, OR. 1-503-671-9500, fax 1-503-671-9501, www.orcad.com.

IrDA controller simplifies interfacing, protocol issues

The TIR2000 IC controller from Texas Instruments provides an IrDA-compliant data link to and from the ISA bus. The device comes in a 64-pin TQFP, manages the link while encoding data bits into an IR-compatible format, and performs reverse decoding. It supports the IrDA 1.0 and 1.1 protocols for speeds as high as 4 Mbps as well as Sharp ASK and standard-TV IR standards. The IC includes a user-selectable 16- or 64-byte FIFO buffer for data buffering and increased system efficiency, as well as system-interrupt and DMA options. The $6.42 (1000) TIR2000 requires 3.3 or 5V and includes several power-down modes to conserve battery life. A companion device, the $1.15 (1000) TSLM1100 IR transceiver interfaces directly with the TIR2000 controller to provide the physical link. You can also use the controller with IR transceivers from other vendors.

--by Bill Schweber

Texas Instruments Inc, Dallas, TX.1-800-477-8924, www.ti.com/sc/msp.

Static-timing-analysis tool accelerates chip design

Add Mentor Graphics to the growing list of EDA companies offering a static-timing analyzer for chip designers. SST Velocity takes your VHDL, Verilog, or EDIF input and lets you determine all on-chip timing paths without the use of simulation vectors. In addition, a linear-analysis algorithm and hierarchical analysis capability lets you analyze chip designs in reasonable runtimes.

SST Velocity can handle chips with multiple asynchronous clock domains and complex clock-tree structures, including gated and multiplexed clocks. The tool includes specialized algorithms for eliminating false paths, speeding analysis setup time and simplifying what-if analyses during early design. A simplified GUI for analysis setup and graphical output display helps you enter your design and understand a subsequent timing analysis. Running under Unix, SST Velocity costs $37,000.

--by Jim Lipman

Mentor Graphics, Wilsonville, OR. 1-503-685-7000, fax 1-503-685-1202, www.mentorg.com.

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