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41 Engineering a More Sustainable Future | ADI Resolver (Coupled) Encoder A resolver encoder has some advantages, such as high mechanical reliability and accuracy; however, compared to a magnet and ADA4571, a resolver is expensive. The AD2S1200 converts the signal from the resolver to the digital angle/angular rate. Figure 10 shows the resolver signal chain. Two amplifiers are used to create a third-order Butterworth low-pass filter to pass the resolver signals to the AD2S1200. Refer to Circuit Note CN0276 for more information. To save space and reduce design complexity, the LTC4332 SPI extender is recommended. The LTC4332 enables system partitioning, providing the option of placing the microcontroller at the servo, rather than at the encoder. If a microcontroller is required at the encoder, the MAX32672 SPI interface can be used as the direct link to the AD2S1200 and the ADM3065E RS-485 transceiver can be used instead of the LTC4332. If the LTC4332 is used, the AD2S1200 SPI output is converted to a robust differential fieldbus interface. The LTC4332 includes three subordinate select lines, so additional sensors such as MEMS and temperature sensors can be wired on the same bus as the AD2S1200. Table 6: Resolver Encoder Signal Chain Recommended Components Component Recommended Part Numbers MEMS Accelerometer ADXL371, ADXL372, ADXL314, ADXL375 Temperature Sensor ADT7320 Power (LDO Regulator) ADP120, ADP220, ADP320, LT3023, LT3029, LT3024, LT3027 Precision Op Amp AD8694, AD8692, AD8397 Transceiver (SPI/RS-485, RS-485) LTC4332, ADM3065E Resolver-to-Digital Converter AD2S1200, AD2S1205, AD2S1210 Conclusion Analog Devices' deep domain expertise and advanced technologies help partners design the industrial motor encoders and networks of the future. Integrating asset health insights in encoders is made easy with tiny and powerful microcontrollers, ADXL371 MEMS, and ADT7320 temperature sensors. ADI's industry-leading AMR magnetic sensors, such as the ADA4571, improve reliability, reduce size and weight, and are easier to integrate into an encoder compared to optical or resolver sensing solutions. High accuracy and repeatability for pick and place machines and robots are possible with mid to high end ADCs such as the AD7380 or AD7760. Figure 10: Resolver encoder signal chain. 10 1 Dayin Xu. "100BASE-T1L for Motor Feedback Communication." Rockwell Automation, May 2022. 2 Stephen Bradshaw, Christian Nau, and Enda Nicholl. "Multiturn Position Sensor Provides True Power-On Capabilities with Zero Power." Analog Dialogue, Vol. 56, No. 3, September 2022. 3 Jonathan Colao. "On-Chip Oversampling for the Analog Devices, Inc., AD7380 Family of SAR ADCs." Analog Devices, Inc., June 2020. 4 "EnDat 2.2—Bidirectional Interface for Position Encoders." Heidenhain, September 2017. 5 Richard Anslow and Neil Quinn. "Going Faster and Further with Fieldbus." Analog Devices, Inc., March 2020.