Nonvolatile Memory, Dual 1024-Position Digital Resistor Data Sheet ADN2850 FEATURES FUNCTIONAL BLOCK DIAGRAM Dual-channel, 1024-position resolution ADN2850 ADDR 25 k, 250 k nominal resistance RDAC1 CS DECODE REGISTER Maximum 8% nominal resistor tolerance error CLK W1 SERIAL Low temperature coefficient: 35 ppm/C SDI INTERFACE B1 2.7 V to 5 V single supply or 2.5 V dual supply RDAC1 SDO EEMEM1 Current monitoring configurable function POWER-ON PR SPI-compatible serial interface RESET RDAC1 Nonvolatile memory stores wiper settings REGISTER WP EEMEM W2 Power-on refreshed with EEMEM settings CONTROL RDY B2 Permanent memory write protection RDAC2 EEMEM2 Resistance tolerance stored in EEMEM V DD I V 1 1 26 bytes extra nonvolatile memory for user-defined 26 BYTES CURRENT V SS RTOL* information USER EEMEM MONITOR I V GND 2 1M programming cycles 2 100-year typical data retention *R FULL SCALE TOLERANCE. WB APPLICATIONS Figure 1. SONET, SDH, ATM, Gigabit Ethernet, DWDM laser diode The EEMEM content can be restored dynamically or through driver, optical supervisory systems PR WP external strobing, and a function protects EEMEM Mechanical rheostat replacement contents. To simplify the programming, the independent or Instrumentation gain adjustment simultaneous linear-step increment or decrement commands Programmable filters, delays, time constants can be used to move the RDAC wiper up or down, one step at a Sensor calibration 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 GENERAL DESCRIPTION RDAC wiper setting. The ADN2850 is a dual-channel, nonvolatile memory, digitally The ADN2850 patterned resistance tolerance is stored in the controlled resistor with 1024-step resolution, offering guaranteed EEMEM. The actual full scale resistance can, therefore, be maximum low resistor tolerance error of 8%. The device performs the same electronic adjustment function as a mechanical rheostat known by the host processor in readback mode. The host can with enhanced resolution, solid state reliability, and superior low execute the appropriate resistance step through a software temperature coefficient performance. The versatile programming routine that simplifies open-loop applications as well as of the ADN2850 via an SPI-compatible serial interface allows 16 precision calibration and tolerance matching applications. modes of operation and adjustment including scratchpad The ADN2850 is available in the 5 mm 5 mm 16-lead frame programming, memory storing and restoring, increment/ chip scale LFCSP and thin, 16-lead TSSOP. The device is decrement, 6 dB/step log taper adjustment, wiper setting guaranteed to operate over the extended industrial temperature readback, and extra EEMEM for user-defined information such as range of 40C to +85C. memory data for other components, look-up table, or system In this data sheet, the terms nonvolatile memory and EEMEM identification information. are used interchangeably and the terms digital resistor and In the scratchpad programming mode, a specific setting can RDAC are used interchangeably be programmed directly to the RDAC 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. Rev. F Document Feedback Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. rights of third parties that may result from its use. Specifications subject to change without notice. No Tel: 781.329.4700 20022016 Analog Devices, Inc. All rights reserved. license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Technical Support www.analog.com Trademarks and registered trademarks are the property of their respective owners. 02660-001ADN2850 Data Sheet TABLE OF CONTENTS Features .............................................................................................. 1 Daisy-Chain Operation ............................................................. 17 Applications ....................................................................................... 1 Terminal Voltage Operating Range ......................................... 17 General Description ......................................................................... 1 Advanced Control Modes ......................................................... 19 Functional Block Diagram .............................................................. 1 RDAC Structure.......................................................................... 20 Revision History ............................................................................... 2 Programming the Variable Resistor ......................................... 21 Specif icat ions ..................................................................................... 4 Programming Examples ............................................................ 21 Electrical Characteristics25 k, 250 k Versions ............... 4 EVAL-ADN2850SDZ Evaluation Kit ....................................... 22 Interface Timing and EEMEM Reliability Characteristics25 Applications Information .............................................................. 23 k, 250 k Versions .................................................................... 6 Gain Control Compensation .................................................... 23 Absolute Maximum Ratings ............................................................ 8 Programmable Low-Pass Filter ................................................ 23 ESD Caution .................................................................................. 8 Programmable Oscillator .......................................................... 23 Pin Configurations and Function Descriptions ........................... 9 Optical Transmitter Calibration with ADN2841 ................... 24 Typical Performance Characteristics ........................................... 11 Incoming Optical Power Monitoring ...................................... 24 Test Circuits ................................................................................. 14 Resistance Scaling ...................................................................... 25 Theory of Operation ...................................................................... 15 Resistance Tolerance, Drift, and Temperature Coefficient Scratchpad and EEMEM Programming .................................. 15 Mismatch Considerations ......................................................... 26 Basic Operation .......................................................................... 15 RDAC Circuit Simulation Model ............................................. 26 EEMEM Protection .................................................................... 16 Outline Dimensions ....................................................................... 27 Digital Input and Output Configuration ................................. 16 Ordering Guide .......................................................................... 27 Serial Data Interface ................................................................... 16 REVISION HISTORY 4/16Rev. E to Rev. F Changes to Figure 1 ........................................................................... 1 Changed CP-16-6 to CP-16-31 .................................... Throughout Changes to Specifications Section ................................................... 3 Changes to General Description Section ...................................... 1 Changes to Table 2 ............................................................................. 5 Changes to Figure 4 and Table 4 ..................................................... 9 Changes to Absolute Maximum Ratings Section .......................... 7 Changes to Figure 5 and Table 5 ................................................... 10 Changes to Pin Configuration and Function Descriptions Updated Outline Dimensions ....................................................... 27 S ection ................................................................................................. 8 Changes to Typical Performance Characteristics Section ........ 10 Changes to Ordering Guide .......................................................... 27 Added Figure 15, Figure 16, and Figure 17 ................................. 11 6/12Rev. D to Rev. E Changes to Figure 21 ...................................................................... 12 Changes to Table 1 Conditions ....................................................... 4 Changes to Theory of Operation Section.................................... 13 Removed Positive Supply Current RDY and/or SDO Floating Changes to Figure 25 ...................................................................... 14 Parameters and Negative Supply Current RDY and/or SDO Changes to Programming Variable Resister Section ................. 19 Floating Parameters, Table 1 ........................................................... 4 Changes to Table 13 ....................................................................... 19 Updated Outline Dimensions ....................................................... 25 Changes to EVAL-ADN2850EBZ Evaluation Kit Section ........ 20 Added Gain Control Compensation Section .............................. 21 Added Endnote 2 to Ordering Guide .......................................... 25 Added Programmable Low-Pass Filter Section .......................... 21 4/11Rev. C to Rev. D Added Programmable Oscillator Section.................................... 21 Changes to Figure 10 ...................................................................... 10 Added Resistance Tolerance, Drift, and Temperature Coefficient Mismatch Considerations Section ........................... 24 4/11Rev. B to Rev. C Changes to Outline Dimensions Section .................................... 25 Updated Format .................................................................. Universal Changes to Ordering Guide .......................................................... 25 Changes to EEMEM Performance ................................... Universal Changes to Features Section............................................................ 1 Changes to Applications Section .................................................... 1 Changes to General Description Section ...................................... 1 Rev. F Page 2 of 30