DC to 204 kHz, Dynamic Signal Analysis, Precision …

1 DC to 204 kHz, Dynamic Signal Analysis, Precision 24-Bit ADC with Power Scaling Data Sheet AD7768-1 Rev. 0 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 rights of third parties that may result from its use. Specifications subject to change without notice. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Trademarks and registered trademarks are the property of their respective owners. One Technology Way, Box 9106, Norwood, MA 02062-9106, Tel: 2018 Analog Devices, Inc. All rights reserved. Technical Support FEATURES ADC for single-channel low power, platform DAQ designs Wide BW Sinc filter BW range: DC to 204 kHz Low ripple FIR BW range: DC to kHz Precision ac and dc performance dB Dynamic range 120 dB THD ppm of FSR INL, 30 V offset error, 30 ppm of FSR gain error Programmable ODR, filter type, and latency ODR values up to 1024 kSPS Linear phase digital filter options Low ripple FIR filter: dB maximum pass-band ripple, dc to kHz Low latency sinc5 filter Low latency sinc3 filter enabling 50 Hz/60 Hz rejection Programmable power consumption and bandwidth Fast, highest speed k H z BW, mW (sinc5 filter) kH z BW, mW (FIR filter) Median, half speed: kH z BW, mW (FIR filter) Low power, low speed.

2 K Hz BW, mW (FIR filter) Power supply AVDD1 AVSS = V typical AVDD2 AVSS = V to V typical Analog supplies can run from split supply (true bipolar) IOVDD DGND = V to V typical Low power mode can run from single V supply Pin control or SPI interface configurable Suite of diagnostic check mechanisms Temperature, interface CRC, and memory map CRC Package: 28-lead, 4 mm 5 mm, LFCSP Temperature range: 40 C to +125 C APPLICATIONS Platform ADC to serve a superset of measurements and sensor types Sound and vibration, acoustic, and material science research and development Control and hardware in loop verification Condition monitoring for predictive maintenance Electrical test and measurement Audio testing and current and voltage measurement Clinical EEG, EMG, and ECG vital signs monitoring USB-, PXI-, and Ethernet-based modular DAQ Channel to channel isolated modular DAQ designs FUNCTIONAL BLOCK DIAGRAM CONTROLBLOCKAIN+AIN VCMAVSSCLKSELMODE3 TO MODE0(GPIO3 TO GPIO0)

3 PIN/SPIMCLK/XTAL2 XTAL1 SYNC_OUTSYNC_INAVDD1 DGNDWIDEBANDLOW RIPPLEFILTERSINC5 LOW LATENCYFILTERSINC3 FILTERENABLING50Hz/60 HzREJECTIONADCDATASERIALINTERFACEPOWERSC ALABLE - ADCPRECHARGEBUFFERSAVDD2 REGCAPAREF+REF 2 RESETDRDYCSDOUT/RDYSDISCLKAD7768-116481- 001 Figure 1. AD7768-1 Data Sheet Rev. 0 | Page 2 of 76 TABLE OF CONTENTS Features .. 1 Applications .. 1 Functional Block Diagram .. 1 Revision History .. 3 General Description .. 4 Specifications .. 5 3 V Operation .. 10 Timing Specifications .. 11 V Timing Specifications .. 12 Absolute Maximum Ratings .. 16 Thermal Resistance .. 16 ESD Caution .. 16 Pin Configuration and Function Descriptions .. 17 Typical Performance Characteristics .. 19 Terminology .. 27 Theory of Operation .. 28 Clocking, Sampling Tree, and Power Scaling.

4 28 Noise Performance and 29 Core Converter .. 31 Clocking and Clock Selection .. 34 Digital Filtering .. 34 Decimation Rate Control .. 38 Antialiasing Filtering .. 38 Getting Started .. 39 Power Supplies .. 41 Device Configuration Method .. 41 Pin Control Mode 42 SPI Control Overview .. 44 SPI Control Mode .. 45 Digital Interface .. 48 Data Conversion Modes .. 52 Synchronization of Multiple AD7768-1 Devices .. 53 Additional Functionality of the AD7768-1 .. 55 Applications Information .. 56 Analog Input Recommendations .. 56 Antialiasing Filter Design Considerations .. 57 Recommended Interface .. 58 Programmable Digital Filter .. 59 Electromagnetic Compatibility (EMC) Testing .. 61 AD7768-1 Subsystem Layout .. 62 Register Summary .. 63 Register Details .. 65 Component Type Register.

5 65 Unique Product ID Registers .. 65 Device Grade and Revision Register .. 65 User Scratchpad Register .. 65 Device Vendor ID Registers .. 65 Interface Format Control Register .. 66 Power and Clock Control Register .. 66 Analog Buffer Control Register .. 67 VCM Control Register .. 68 Conversion Source Select and Mode Control Register .. 68 Digital Filter and Decimation Control Register .. 69 Sinc3 Decimation Rate (MSB Register) .. 70 Sinc3 Decimation Rate (LSB Register) .. 70 Periodic Conversion Rate Control Register .. 70 Synchronization Modes and Reset Triggering Register .. 70 GPIO Port Control Register .. 71 GPIO Output Control Register .. 71 GPIO Input Read Register .. 71 Offset Calibration MSB Register .. 71 Offset Calibration MID Register .. 72 Offset Calibration LSB 72 Gain Calibration MSB Register.

6 72 Gain Calibration MID Register .. 72 Gain Calibration LSB Register .. 73 SPI Interface Diagnostic Control Register .. 73 ADC Diagnostic Feature Control Register .. 73 Digital Diagnostic Feature Control Register .. 73 Conversion Result Register .. 74 Device Error Flags Master Register .. 74 SPI Interface Error Register .. 74 ADC Diagnostics Output Register .. 74 Digital Diagnostics Output Register .. 75 MCLK Diagnostic Output Register .. 75 Coefficient Control Register .. 75 Coefficient Data Register .. 75 Access Key Register .. 75 Outline Dimensions .. 76 Ordering Guide .. 76 Data Sheet AD7768-1 Rev. 0 | Page 3 of 76 REVISION HISTORY 5/2018 Revision 0: Initial Ve r s i o n AD7768-1 Data Sheet Rev. 0 | Page 4 of 76 GENERAL DESCRIPTION The AD7768-1 is a low power, high performance, - analog-to-digital converter (ADC), with a - modulator and digital filter for Precision conversion of both ac and dc signals.

7 The AD7768-1 is a single-channel version of the AD7768, an 8-channel, simultaneously sampling, - ADC. The AD7768-1 provides a single configurable and reusable data acquisition (DAQ) footprint, which establishes a new industry standard in combined ac and dc performance and enables instrumentation and industrial system designers to design across multiple measurement variants for both isolated and nonisolated applications. The AD7768-1 achieves a dB Dynamic range when using the low ripple, finite impulse response (FIR) digital filter at 256 kSPS, giving kHz input bandwidth (BW), combined with ppm integral nonlinearity (INL), 30 V offset error, and 30 ppm gain error. A wider bandwidth, up to 500 kHz Nyquist (filter 3 dB point of 204 kHz), is available using the sinc5 filter, enabling a view of signals over an extended range.

8 The AD7768-1 offers the user the flexibility to configure and optimize for input bandwidth vs. output data rate (ODR) and vs. power dissipation. The flexibility of the AD7768-1 allows Dynamic analysis of a changing input Signal , making the device particularly useful in general-purpose DAQ systems. The selection of one of three available power modes allows the designer to achieve required noise targets while minimizing power consumption. The design of the AD7768-1 is unique in that it becomes a reusable and flexible platform for low power dc and high performance ac measurement modules. The AD7768-1 achieves the optimum balance of dc and ac performance with excellent power efficiency. The following three operating modes allow the user to trade off the input bandwidth vs. power budgets: Fast mode offers both a sinc filter with up to 256 kSPS and kHz of bandwidth, and mW of power consumption, or a FIR filter with up to 256 kSPS, kHz of bandwidth and mW of power consumption.

9 Median mode offers a FIR filter with up to 128 kSPS, kHz of bandwidth and mW of power consumption. Low power mode offers a FIR filter with up to 32 kSPS, kHz of bandwidth and mW of power consumption. The AD7768-1 offers extensive digital filtering capabilities that meet a wide range of system requirements. The filter options allow configuration for frequency domain measurements with tight gain error over frequency, linear phase response requirements (brick wall filter), a low latency path (sinc5 or sinc3) for use in control loop applications, and measuring dc inputs with the ability to configure the sinc3 filter to reject the line frequency of either 50 Hz or 60 Hz. All filters offer programmable decimation. A MHz sinc5 filter path exists for users seeking an even higher ODR than is achievable using the low ripple FIR filter.

10 This path is quantization noise limited. Therefore, it is best suited for customers requiring minimum latency for control loops or implementing custom digital filtering on an external field programmable gate array (FPGA) or digital Signal processor (DSP). The filter options include the following: A low ripple FIR filter with a dB pass-band ripple to kHz. A low latency sinc5 filter with up to a MHz data rate to maximize control loop responsiveness. A low latency sinc3 filter that is fully programmable, with 50 Hz/60 Hz rejection capabilities. When using the AD7768-1, embedded analog functionality within the AD7768-1 greatly reduces the design burden over the entire application range. The precharge buffer on each analog input decreases the analog input current compared to competing products, simplifying the task of an external amplifier to drive the analog input.