August 15, 1997

WHAT'S HOT IN THE DESIGN COMMUNITY

Ruggedized UPSs suit harsh environments

The ACG1250U and ACG1250U-24 series of UPSs from Acumentrics targets harsh physical and electrical environments. The UPS family complies with MIL-STD-810E environmental and vibration standards, as well as MIL-STD-461C norms for emissions. The units accept any ac-input voltage from 80 to 265V at line frequencies of 47 to 66 Hz and simultaneously accommodate dc-input voltages of 22 to 32V. If the ac-input power fails, the dc input automatically takes over and supplies power to the load. When the dc-input power fails, the UPS switches to its internal battery pack. The supplies use an online topology with power-factor correction (PFC) to recreate a clean sine wave. PFC helps users comply with IEC 555 standards for allowable harmonics. The UPS units provide 1250-VA output at 120V ac, 60 Hz. The ACG-1250U-24 provides an additional 24V-dc output for applications requiring dc power. The ACG1250U and ACG1250U-24 cost $4199 and $4299, respectively.

--by Bill Travis

Acumentrics Corp, Westwood, MA. 1-617-461-8251, fax 1-617-461-1261.

No-latency SRAMs tackle fast-changing data

The No Bus Latency (NoBL) synchronous pipelined SRAMs from Cypress Semiconductor eliminate the write-to-read turnaround latency that can impact memory bandwidth in data-centric applications, such as multimedia and network equipment. In contrast, standard synchronous pipeline- burst SRAMs (PBSRAMs) typically have a two-clock write-to-read latency. This latency has less effect on code-cache designs, which have many long read sequences and a higher proportion of reads to writes than do data-centric applications. A few years ago, with its late-write SRAMs, Motorola (Austin, TX) made a stab at solving the performance problem by reducing latency to one clock cycle.

The Cypress technique is conceptually similar to the approach Integrated Device Technology (IDT) (Santa Clara, CA) uses in its Zero Bus Turnaround (ZBT) architecture, which the company announced last year. Table 1 compares a PBSRAM, a late-write SRAM, and either NoBL or ZBT (pipelined or flow-through) SRAM in the number of clocks, including initial pipeline fill, to complete an eight-access, read-write-read-write-read-write-read-write sequence.

Compared with today's 1-Mbit ZBT memories, Cypress' planned devices are both larger (2 and 4 Mbits) and wider (×32 and ×36 bits), and they integrate the four-access, linear or interleaved, burst-address counter function. They also operate as fast as 133 MHz at 3.3V. They provide almost-100% package and pinout compatibility with PBSRAM, enabling you to create and populate a generic board design based on memory availability, price, and performance requirements. Unlike ZBT memories, however, first-generation NoBL SRAMs provide no optional flow-through outputs, which reduce initial read latencies at lower clock frequencies. Integrated Silicon Solutions Inc (ISSI) (Santa Clara, CA) plans to act as an alternate source for the NoBL architecture.

Cypress' NoBL memories use the relatively new 0.35-µm, six-transistor RAM3 cell process. Six-transistor cells commonly provide lower power consumption, higher immunity to alpha-particle and other reliability limiters, and better performance at lower voltages than do four-transistor, two-resistor alternatives. The initial NoBL product offering is the 100-pin, TQFP, 64-kbit×32-bit (2-Mbit) CY7C1334, which will be available for sampling in October for $12 (1000). Additional family members, in-cluding flow-through versions, will follow in early 1998 and will retain backward-compatible packages and pinouts with the CY7C1334.

In response, IDT, Motorola, and Micron (Boise, ID) plan a common 100-pin PQFP and pinout for future ZBT-interface memories beginning at 4 Mbits with upgradability to 8 and 16 Mbits. The three companies have not yet released detailed specifications, making the degree of compatibility with Cypress/ISSI NoBL devices hard to determine.

--by Brian Dipert

Cypress Semiconductor, San Jose, CA. 1-408-943-2600, fax 1-408-943-2741, www.cypress.com.

Regulator ICs answer the call for more power

Despite all the micropower ICs available, many systems still require lots of amps from their supplies. For load currents of 50 to 60A, the LT1339 current-mode synchronous switching regulator from Linear Technology Corp includes N-channel drivers that can handle inputs as high as 60V and drive gates with capacitance as high as 10,000 pF. The device is well-suited to step-down applications, such as converting 48V telephone-company supplies to 5V, and high-voltage industrial-control applications. An adaptive nonoverlapping gate-drive circuit prevents shoot-through and gate-drive undervoltage lockout to avoid simultaneous turn-on of the external power MOSFETs. You can synchronize the LT1339's operating frequency to an external source as high as 150 kHz to minimize RFI and noise in sensitive bands. The 20-lead DIP or SOIC device costs $4.85 (1000).

Unitrode's UC3827 PWM controller family combines both a buck stage and a push-pull stage for multiple-output and high-voltage applications. Typical operating frequency is 500 kHz, and output power is 200W. The UC3827-1 for current-fed operation has user-programmable overlap time in the push-pull stage to prevent ringing and voltage stress on external FETs. In contrast, the UC3827-2 for voltage-fed operation has a programmable time gap to prevent short-circuiting the output transformer. The ICs each have one output for controlling an external FET to provide regulated voltage to the transformer center tap and two outputs for driving the external FETs for the push-pull stage. Prices for the ICs in 24-pin inline or SOIC packages begin at $3.50 (1000).

If you need a linear regulator, Cherry Semiconductor's CS-5210 features low dropout voltage and 1-µsec transient response with output voltage you can set at 1.25 to 4.5V via a resistive divider. Dropout voltage is typically 1.2V at full load and 1.4V maximum. The device comes in a three-lead plastic TO-220 package with a heat-sink tab and costs $2.53 (10,000); 7 and 8A versions are also available with lower dropout at the same price.

--by Bill Schweber

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

Unitrode Corp, Merrimack, NH. 1-603-424-2410, www.unitrode.com.

Cherry Semiconductor Corp, East Greenwich, RI. 1-401-885-3600, www.cherry-semi.com.

Discrete and complex ICs answer PCS needs

To design a personal-communications system (PCS), you'll likely use both basic discrete devices and ICs with higher levels of integration. California Eastern Laboratories features two bipolar npn transistors from NEC that are designed as low-noise amplifiers in cable-TV and wireless applications. The $0.58 (100,000) NE461M02 features a gain of 8.3 dB at 1 GHz, f_T of 5.5 GHz, and a noise figure of 1.5 dB at 1 Ghz; the corresponding figures for the $0.31 (100,000) NE856M02 are 12 dB, 6.5 GHz, and 1.1 dB, respectively. In addition, the NE461M02 has third-order intermodulation distortion of 82 dB with V_CE of 10V and I_C of 50 mA. Both are available in four-pin, minimold, dual-emitter packages, which have lower emitter inductance and better gain performance than does the common SOT-89 package.

For CDMA applications, wireless local loops, and microcell designs, two PCS down-converter ICs from Triquint Semiconductor integrate a low-noise amplifier, a mixer, an IF amplifier, and a local-oscillator buffer in a 24-pin QSOP. The TQ9225, with a local-oscillator range of 1710 to 1790 MHz and an IF range of 210 to 212 MHz, and the TQ9228, with corresponding ranges of 2015 to 2075 MHz and 84 to 86 MHz, are 2.7 to 4V GaAs devices that support the IS-95 and -98 standards. RF performance specifications for the TQ9225 are a conversion gain of 28 dB, a noise figure of 2.4 dB, and an input third-order intercept point of ­9 dBm; the TQ9228's figures are similar. The overall architecture is split into blocks that provide maximum low-noise-amplifier dynamic range, and the IF output is differential for enhanced performance. The ICs cost $3.86 (100,000).

--by Bill Schweber

California Eastern Laboratories, Santa Clara, CA. 1-408-988-3500, fax 1-408-988-0279, www.cel.com.

Triquint Semiconductor Inc, Hillsboro, OR. 1-503-615-9000, fax 1-503-615-8900, www.triquint.com.

Utility puts zip into Windows file management

If you think you don't need Mijenix's ZipMagic because you already have a Zip utility, think again. ZipMagic is different. Several packages put a Windows "front end" on PKZip, PKware's (Brown Deer, WI) classic MS-DOS-based file-compression utility. Good as they are, the other packages seem terribly clumsy after you've tried ZipMagic. ZipMagic can profoundly influence the way you use your PC and greatly simplify using Zip files. Considering the size of data files created by Microsoft applications, such as Word and Excel, it's a wonder that everyone who uses a PC doesn't want to compress every data file.

ZipMagic lets you use the Windows File Manager to view lists of files in Zip archives as if the archives had never been compressed. The archives appear as directories in the File Manager and the file-management dialogue boxes that you can open from Windows applications. Entries for files within archives look the same as those for uncompressed files. You can execute archived program files by simply double-clicking on their names; you need not extract the files. You can also use a string-search engine to search compressed and uncompressed files without thinking about which are compressed. Mijenix's WizManager, an enhancement of the Win 3.1 File Manager, contains such a search engine. With ZipMagic in operation, you can also use antivirus software to find virus-infected files within Zip archives. Moreover, compressing or uncompressing a file or directory is as simple as renaming it; add a .ZIP suffix to compress; remove the suffix to reverse the operation.

And ZipMagic doesn't use a lot of space on your hard drive. The program files consume less than 1.25 Mbytes (Win 3.1 version; there is a separate version for Win 95 and NT). You can configure ZipMagic to start automatically when you start Windows or you can enable ZipMagic from a drop-down menu that the installation adds to the File Manager's menu bar. Even with ZipMagic disabled (so that the File Manager displays Zip archives as files, not directories), the package's other file-management functions are available from the drop-down menu. If you have dozens or hundreds of Zip archives on your hard drive, enabling or disabling ZipMagic involves waiting a few seconds. I recommend that you not automatically enable ZipMagic when you start Windows. If your hard drive contains one or more corrupted Zip archives in a partition that you log into when Windows starts, Windows may fail to open. Once Windows is open, you can use ZipMagic's Check Integrity function to find corrupted archives and, in many cases, fix the problems.

ZipMagic is shareware; you can download a fully functional version from Mijenix's Web site. If you want to continue using the package after trying it for 30 days, you must pay $39.95 for it. By the way, Mijenix's tech support, which you can contact via e-mail, is prompt, courteous, and helpful.

--by Dan Strassberg

Mijenix Corp, Madison, WI. 1-608-277-1971, fax 1-608-277-1981, sales@mijenix.com, www.mijenix.com.

Chip place-and-route tools hit the fast track

The new version of SonIC, Silicon Valley Research's cell-based place-and-route tool, uses a new placer that can place hundreds of thousands of cells in a few hours. When you couple the tool with the company's area router, you get a place-and-route system that substantially cuts chip-layout time over previous SonIC tools.

The timing-driven place-and-route system includes the Analog Tool Box (ATB), an online Spice-level simulator. ATB models each net in the chip as a distributed-RC tree, simulating pin-to-pin delays with accuracy comparable with Spice, according to the company. It provides back-annotated resistances, capacitances, and path delays in standard-delay format (SDF) to verify the performance of the completed chip layout.

SonIC also features automatic power routing and clock-tree synthesis with automatic buffer insertion and clock-skew control. SonIC comes in four flavors with 10,000 to 250,000 blocks and cells. Prices range from $180,000 to $240,000, depending on component capacity.

--by Jim Lipman

Silicon Valley Research, San Jose, CA. 1-800-624-9978, fax 1-408-361-0330, www.svri.com.

New PowerPC outruns previous devices

At the International Solid State Circuits Conference in San Francisco in February, the Motorola/IBM Power PC team announced the MPC750 PowerPC architecture. Although the MPC750 has some characteristics of the Power PC 603e and 604e systems, the new device adds some architectural features that allow it to hit 11.03 SPECint95 and 8.10 SPECfp95 at 244 MHz. The CPU's maximum power consumption is 5W at 250 MHz and 2.5V.

Using a four-stage pipeline, the MPC750 executes two instructions per cycle. The CPU also features a double-path FPU that uses two clocks to perform a double-precision calculation; dual 32-kbyte, eight-way set-associative caches; and a Level 2 cache controller with a backside Level 2 bus. The MPC750 contains a thermal-management-assist unit (TAU), which monitors and compares the junction temperature with user-programmable values. The TAU is useful for mobile applications in which battery power and heat buildup are critical. IBM sells the 225-MHz MCP750 in a 360-pin BGA for $345.

--by Markus Levy

IBM Corp, Hopewell Junction, NY. 1-800-769-3772, www.chips.ibm.com.

Motorola, Austin, TX. 1-512-434-1502, www.mot.com/PowerPC.

Load switch lets you add or drop
subsystems to cut battery drain

A family of high-side power-load switches from Fairchild Semiconductor lets you selectively shut down circuitry within your system to reduce power consumption and extend battery life. The FDC6322L handles loads as high as 100 mA, and the FDC6323L handles loads as high as 1A, both at 3.3 to 5V; the FDC6324L handles 5 and 12V, 1A loads. A digital control line opens and closes the input-to-output supply path. Voltage drop across the DMOS devices is 0.2 to 0.3V, depending on operating conditions. The load switches come in six-lead SOT packages, which are slightly larger than SOT-23 devices, and cost $0.20 to $0.30 (100,000), depending on model.

--by Bill Schweber

Fairchild Semiconductor Corp, Santa Clara, CA. 1-408-721-2049, www.fairchildsemi.com.

Pots meet MIL specs,
endure 2 million revolutions

A series of trimmers and multiturn potentiometers from Spectrol complies with MIL-STD-202 and MIL-R-22097 environmental and performance standards. The DESC-qualified multiturn pots are available in three-, five-, and 10-turn models and use either wire-wound or conductive-plastic resistive elements. Available values range from 15 ohms to 200 kilo ohms with ±3% tolerance and power ratings as high as 8W at 40°C. The potentiometers cost $7.64 (1000). A line of 1/4-in. trimmers meets the same MIL standards. The trimmers use cermet resistive elements and offer 10 ohm to 2 mega ohms ±10% values. The units include a multifinger wiper, a sealed housing for immersion cleaning, and a rotor that adjusts automatically. Power rating is 0.5W at 70°C. Prices range from $0.51 to $1.20 (1000).

--by Bill Travis

Spectrol Electronics Corp, Ontario, CA. 1-909-923-3313, fax 1-909-923-6765.

Converters fit more channels,
resolution into small, low-power designs

If you don't need blazing speed, you can get D/A and A/D converters in small, high-density packages. The four-channel, 12-bit MAX1246 ADC from Maxim features an internal reference sample as fast as 133k samples/sec. Available in a 16-pin QSOP, which is the same size as an SO-8, the serial-interface converter consumes 4 mW with 2-µA drain in standby mode. Integral nonlinearity is ±0.5 LSB over temperature; commercial-, extended-industrial-, and military-temperature versions are available. Operating supply for this IC is 2.7 to 3.6V. The commercial-range version costs $6.15 (1000).

On the D/A-converter side, Linear offers the LTC1590, a dual, serial-input, multiplying device in a 16-pin plastic DIP and SO package. The device targets precision level-setting applications. The current-output converters provide four-quadrant multiplication with differential and integral nonlinearity lower than ±0.5 LSB and gain error less than ±gain error over temperature. The IC operates from a nominal 5V supply and draws 10 µA of supply current. Price is $6.90 (1000).

--by Bill Schweber

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

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

High-end ADC pushes 16 bits at 1M sample/sec

For medical-imaging, radar, sonar, and instrumentation applications, Datel's ADS-931 ADC provides both frequency- and time-domain specifications. The 40-pin, triple-width DIP device features ­89-dB THD and peak harmonics, 83-dB SNR and distortion, 87-dB SNR, ±0.5-LSB differential nonlinearity, and less-than-60-µV rms noise. The edge-triggered converter includes an S/H amplifier, a reference, and error-correction and autocalibration circuitry. It accepts an analog input range of ±2.75V, uses a bipolar ±5V supply, and dissipates 1.85W. The device operates over the 0 to 70°C temperature range and costs $397 (100); a ­55 to +125°C version costs $497 (100).

--by Bill Schweber

Datel Inc, Mansfield, MA. 1-508-339-3000, fax 1-508-339-6456.

WLAN DSSS chip set adds receiver functions

The Prism chip set from Harris Semiconductor now provides full-duplex communications for voice and data wireless-local-loop applications with RF-through-baseband signal processing. The chip set lets you build a full-duplex direct-sequence spread-spectrum (DSSS) design operating from 1.7 to 2.7 GHz. Receiver sensitivity is ­11 dBm with an 8.5-dB noise figure at 2.4 GHz, and AGC dynamic range is 90 dB. You can control the analog output power over 75 dB of range for CDMA systems with their large peak-to-average power spans.

The ICs in the chip set include low-noise front-end amplifiers, dual synthesizers, a downconverter, AGC and quadrature-IF demodulators, an up-converter with gain control, and RF power amplifiers. Operating from a 2.7 to 5.5V supply, the full-duplex chip set costs $56 (100,000).

--by Bill Schweber

Harris Semiconductor, Melbourne, FL. 1-800-442-7747, www.semi.harris.com.

IC controls "speeding" buses

For buses operating at 50 MHz or faster, you have to look beyond simple resistor termination for proper perform-ance. Micro Linear's ML6552 active-bus terminator for 60- to 200-MHz buses reduces component count, power consumed by the termination circuitry, and the chances of bus noise and reflections, which cause troublesome intermittent failures or data errors.

The ML6552 supports RAMbus, Gunning transceiver logic (GTL+), low-voltage-TTL, and series-stub-terminated-logic buses. It actively sources and sinks current that the bus needs to 1A maximum with an output of 2.5V from a 5V supply or 1.5V from a 3.3V supply. You can set the output voltage from 1 to 6V for the additional voltages that RAMbus and GTL+ require. One IC supports as many as 80 bus lines with a maximum source and sink current of 12 mA per line--one possible combination. The eight-pin SOIC costs $1.60 (1000).

--by Bill Schweber

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

CALENDAR

Sept 7 to 11

Surface Mount International, San Jose, CA, provides information on array, chip-scale, flip-chip, soldering, and packaging technologies. The keynote address focuses on the revolution in IC packaging. The full conference costs $595. Miller Freeman Inc, Boston, MA. 1-617-821-6720.

Sept 8 to 10

IC Design for Wireless Transceivers, Los Angeles, examines RF electronics with emphasis on monolithic implementation in VLSI technologies. The course presents case studies of complete transceiver systems. Tuition is $1195. Short Course Program, UCLA Extension, Los Angeles, CA. 1-310-825-3344.

Sept 15 to 18

Wireless and Portable Design Conference, Burlington, MA, targets design engineers faced with portability issues. The conference covers both wireless-design concerns, such as RF circuitry, frequency translation, modulation, baseband processing, and DSP, and design-for-portability issues, including battery technologies, dc-converter circuitry, µPs, communications-bus technologies, and low-power analog-circuit design. The Wireless and Portable Design Conference, Hasbrouck Heights, NJ. 1-201-393-6256.

Sept 23

Outlook '98, Boston, sponsored by In-Stat, covers semiconductors, PCs, and communications. Outlook '98 focuses on trends, market projections, pricing pressures, shifting geographical consumption, and expanding end-equipment demand in the electronics industry. The forum will also take place Sept 25 in Dallas and Sept 30 in San Jose, CA. Registration is $455 for In-Stat subscribers and $585 for nonsubscribers. In-Stat, Scottsdale, AZ. 1-602-483-4474.

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