Summit Microelectronics Digital Potentiometer Supplies Superior Resolution, Temperature Stability, and Space Savings for Optical and Communications Applications

7/1/2002 - Summit Microelectronics has announced immediate availability of the SMP9410 quad 10-bit digital potentiometer (ie, DACPOT™ ), a fully integrated device that delivers high resolution and superior temperature stability, two critical features of optical systems. Additionally, the device packs multiple functions on chip, letting system designers avoid the hassles of a discrete solution.

The SMP9410 DACPOT features the industry's highest known temperature stability of ± 15ppm per degree Centigrade. Using DACPOTs with small temperature coefficient characteristics is imperative for setting both bias power and modulation control pins in a laser communication system.

When setting the power level, a low-temperature-coefficient DACPOT minimizes the temperature variation of photodiode response, which can vary by up to ±1.5dBm (about 40%) over temperature. For the modulation settings, low-temperature coefficient helps minimize the temperature variation that causes loss of laser efficiency.

These same DACPOTs can also be included in laser driver gain settings to replace low temperature-coefficient fixed resistors. Each DACPOT can be set through the chip's I2C™ bus to an initial value and set again after system aging.

For accuracy, the SMP9410 can be set to any one of 1024 steps in each its four 10-bit nonvolatile DACs. The device automatically retains the settings during system power up, thereby removing the problems of power-up latency seen in alternative implementations.

Accuracy in the DACPOT is heightened by enabling the four on-chip digital-to-analog-converters (DACs) to retain their settings even when power is removed in the system. This feature allows the DACs to be used to calibrate or initialize such functions as bias currents in laser applications, where the proper setting must be instantly available. The DACs can be operated independently or in parallel.

"Pristine system performance is based on the capabilities of all the devices on a board," stated Art Swift, marketing vice-president of Summit. "The high resolution and temperature stability of this DACPOT brings a new measure of performance to innovative optical and communications systems."

Operating from a single +2.7V to +5.5V supply, the SMP9410 recalls any analog voltage on power up, making it ideal for applications with exacting specifications such as laser bias and modulation current adjustment; power supply trimming and margining; or replacement of current-generation potentiometers.

As with other Summit devices, the SMP9410 integrates traditionally discrete devices for a complete solution. Previously, designers were forced to combine a microcontroller, nonvolatile memory, serial digital-to-analog converters (DACs) and digital/resistive potentiometers to implement a complete DACPOT function. Summit's DACPOT integrates all of these functions, representing a shift in the availability of high-performance and high-density nonvolatile DACs.

Price and Availability
Thanks to its high integration, the SMP9410 is one of the smallest quad 10-bit devices in production with a footprint of 5mm square in a LPCC package. Available also as a TQFP, the SMP9410 DACPOT costs $12.00 each in quantities of 10,000 devices.

Design Tools
To speed design, a complete evaluation kit is available now. It includes an evaluation board for quick IC programming; complete hardware to connect the evaluation board and the parallel port of a laptop or desktop PC; a graphical user interface(GUI) to configure and operate the device. Programming software can be downloaded from Summit's website (

About Summit
Summit Microelectronics supplies semiconductors that manage the power functions in communications system equipment. Using Summit's programmable analog technology, customers can achieve carrier-class availability, the highest standard of reliability available today for telecommunications, data communications and Internet applications.

Founded in 1997, Summit is headquartered in Campbell, California. The Company is ISO 9001 certified. Summit's website is

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