Nonvolatile Memory, Dual 1024-Position Digital Resistor
The ADN2850 is a dual-channel, nonvolatile memory1, digitally controlled resistors2 with 1024-step resolution, offering guaranteed maximum low resistor tolerance error of ±8%. The device performs the same electronic adjustment function as a mechanical rheostat with enhanced resolution, solid state reliability, and superior low temperature coefficient performance. The versatile programming of the ADN2850 via an SPI®-compatible serial interface allows 16 modes of operation and adjustment including scratchpad programming, memory storing and restoring, increment/decrement, ±6 dB/step log taper adjustment, wiper setting readback, and extra EEMEM1 for user-defined information such as memory data for other components, look-up table, or system identification information.
In the scratchpad programming mode, a specific setting can be programmed directly to the RDAC2 register, which sets the resistance between Terminal W and Terminal B. This setting can be stored into the EEMEM and is restored automatically to the RDAC register during system power-on.
The EEMEM content can be restored dynamically or through external PR strobing, and a WP function protects EEMEM contents. To simplify the programming, the independent or simultaneous linear-step increment or decrement commands can be used to move the RDAC wiper up or down, one step at a time. For logarithmic ±6 dB changes in the wiper setting, the left or right bit shift command can be used to double or halve the RDAC wiper setting.
The ADN2850 patterned resistance tolerance is stored in the EEMEM. The actual full scale resistance can, therefore, be known by the host processor in readback mode. The host can execute the appropriate resistance step through a software routine that simplifies open-loop applications as well as precision calibration and tolerance matching applications.
The ADN2850 is available in the 5 mm × 5 mm 16-lead frame chip scale LFCSP and thin, 16-lead TSSOP package. The part is guaranteed to operate over the extended industrial temperature range of −40°C to +85°C.
- SONET, SDH, ATM, Gigabit Ethernet, DWDM laser diode driver, optical supervisory systems
- Mechanical rheostat replacement
- Instrumentation gain adjustment
- Programmable filters, delays, time constants
- Sensor calibration
1 The terms nonvolatile memory and EEMEM are used interchangeably.
2 The terms digital resistor and RDAC are used interchangeably.
At least one model within this product family is in production and available for purchase. The product is appropriate for new designs but newer alternatives may exist.
With versatile programmability, the ADN2850 allows multiple modes of operation, including read/write access in the RDAC and EEMEM registers, increment / decrement of resistance, resistance changes in ±6 dB scales, wiper setting read-back, and extra EEMEM for storing user-defined information, such as memory data for other components or a lookup table.
The ADN2850 supports a dual-supply ±2.25 V to ±2.75 V operation and a single-supply 2.7 V to 5.5 V operation, making the device suited for battery-powered applications and many other applications. In addition, the ADN2850 uses a versatile SPI-compatible serial interface, allowing speeds of up to 50 MHz.
The EVAL-ADN2850SDZ can operate in single-supply and dual-supply mode and incorporates an internal power supply from the USB.
Complete specifications for the ADN2850 part can be found in the ADN2850 data sheet.
Product Selection Guide
Choosing the Correct digiPOT for Your Application
Single-Chip Digitally Controlled Data-Acquisition as Core of Reliable DWDM...
(Analog Dialogue, Vol. 36, No. 5, September-October, 2002)
ADI has always placed the highest emphasis on delivering products that meet the maximum levels of quality and reliability. We achieve this by incorporating quality and reliability checks in every scope of product and process design, and in the manufacturing process as well. "Zero defects" for shipped products is always our goal.
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