3 V/5 V, 450 A 16-Bit, Sigma-Delta ADC Data Sheet AD7715 FEATURES FUNCTIONAL BLOCK DIAGRAM AV DV REF IN() REF IN(+) DD DD Charge-balancing ADC 16-bits no missing codes CHARGE BALANCING ADC 0.0015% nonlinearity - DIGITAL Programmable gain front end AIN(+) MODULATOR FILTER BUFFER PGA Gains of 1, 2, 32 and 128 AIN() Differential input capability A = 1 TO 128 CLOCK MCLK IN GENERATION MCLK OUT Three-wire serial interface SERIAL RESET SPI-, QSPI-, MICROWIRE-, and DSP-compatible INTERFACE SCLK Ability to buffer the analog input REGISTER BANK CS 3 V (AD7715-3) or 5 V (AD7715-5) operation DIN DOUT Low supply current: 450 A maximum 3 V supplies AD7715 DRDY Low-pass filter with programmable output update AGND DGND 16-lead SOIC/PDIP/TSSOP Figure 1. GENERAL DESCRIPTION The AD7715 is a complete analog front end for low frequency CMOS construction ensures very low power dissipation, and measurement applications. The part can accept low level input power-down mode reduces the standby power consumption to signals directly from a transducer and outputs a serial digital 50 W typical. The part is available in a 16-lead, 0.3 inch-wide, word. It employs a - conversion technique to realize up to plastic dual-in-line package (PDIP) as well as a 16-lead 0.3 inch 16 bits of no missing codes performance. The input signal is wide small outline (SOIC W) package and a 16-lead TSSOP applied to a proprietary programmable gain front end based package. around an analog modulator. The modulator output is processed PRODUCT HIGHLIGHTS by an on-chip digital filter. The first notch of this digital filter can be programmed via the on-chip control register allowing 1. The AD7715 consumes less than 450 A in total supply adjustment of the filter cutoff and output update rate. current at 3 V supplies and 1 MHz master clock, making it ideal for use in low-power systems. Standby current is less The AD7715 features a differential analog input as well as a than 10 A. differential reference input. It operates from a single supply (3 V 2. The programmable gain input allows the AD7715 to accept or 5 V). It can handle unipolar input signal ranges of 0 mV to input signals directly from a strain gage or transducer 20 mV, 0 mV to 80 mV, 0 V to 1.25 V and 0 V to 2.5 V. It can removing a considerable amount of signal conditioning. also handle bipolar input signal ranges of 20 mV, 80 mV, 3. The AD7715 is ideal for microcontroller or DSP processor 1.25 V and 2.5 V. These bipolar ranges are referenced to the applications with a three-wire serial interface reducing the negative input of the differential analog input. The AD7715 number of interconnect lines and reducing the number thus performs all signal conditioning and conversion for a of optocouplers required in isolated systems. The part single channel system. contains on-chip registers which allow software control The AD7715 is ideal for use in smart, microcontroller, or DSP- over output update rate, input gain, signal polarity, and based systems. It features a serial interface that can be configured calibration modes. for three-wire operation. Gain settings, signal polarity, and 4. The part features excellent static performance specifications update rate selection can be configured in software using the with 16-bits no missing codes, 0.0015% accuracy, and low input serial port. The part contains self-calibration and system rms noise (<550 nV). Endpoint errors and the effects of calibration options to eliminate gain and offset errors on the temperature drift are eliminated by on-chip calibration part itself or in the system. options, which remove zero-scale and full-scale errors. Rev. E 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 2015 Analog Devices, Inc. All rights reserved. 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. Technical Support www.analog.com 08519-001AD7715 Data Sheet TABLE OF CONTENTS Features .............................................................................................. 1 Digital Filtering........................................................................... 21 Functional Block Diagram .............................................................. 1 Analog Filtering .......................................................................... 23 General Description ......................................................................... 1 C a l ibr at ion ................................................................................... 23 Product Highlights ........................................................................... 1 Using the AD7715 .......................................................................... 26 Revision History ............................................................................... 2 Clocking and Oscillator Circuit ............................................... 26 Specif icat ions ..................................................................................... 3 System Synchronization ............................................................ 26 AD7715-5 ...................................................................................... 3 Reset Input .................................................................................. 27 AD7715-3 ...................................................................................... 5 Standby Mode ............................................................................. 27 Timing Characteristics ................................................................ 8 Accuracy ...................................................................................... 27 Absolute Maximum Ratings ............................................................ 9 Drift Considerations .................................................................. 27 ESD Caution .................................................................................. 9 Power Supplies ............................................................................ 28 Pin Configuration And Function Descriptions .......................... 10 Digital Interface .......................................................................... 29 Terminology .................................................................................... 11 Configuring the AD7715 ............................................................... 31 On-Chip Registers .......................................................................... 12 Microcontroller/Microprocessor Interfacing ............................. 32 Communications Register (RS1, RS0 = 0, 0) .......................... 13 AD7715 to 68HC11 Interface ................................................... 32 AD7715 to 8XC51 Interface ...................................................... 33 Setup Register (RS1, RS0 = 0, 1) Power On/Reset Status: 28 Hex .......................................................................................... 14 AD7715 to ADSP-2184N/ADSP-2185N/ADSP-2186N/ Test Register (RS1, RS0 = 1, 0) .................................................. 15 ADSP-2187N/ADSP-2188N/ADSP-2189N Interface............ 33 Data Register (RS1, RS0 = 1, 1) ................................................ 15 Code For Setting Up The AD7715 ............................................... 34 Output Noise ................................................................................... 16 C Code for Interfacing AD7715 to 68HC11 ........................... 34 AD7715-5 .................................................................................... 16 Applications Information .............................................................. 36 AD7715-3 .................................................................................... 17 Pressure Measurement ............................................................... 36 Calibration Sequences .................................................................... 18 Temperature Measurement ....................................................... 37 Circuit Description ......................................................................... 19 Smart Transmitters ..................................................................... 38 Analog Input ............................................................................... 19 Outline Dimensions ....................................................................... 39 Reference Input ........................................................................... 21 Ordering Guide .......................................................................... 40 REVISION HISTORY 6/15Rev. D to Rev. E Changes to Table 10 ........................................................................ 13 Changed ADSP-2103/ADSP-2105 to ADSP-2184N/ADSP-2185N/ ADSP-2186N/ADSP-2187N/ADSP-2188N/ADSP-2189N ....... 33 Updated Outline Dimensions ....................................................... 39 Changes to Ordering Guide .......................................................... 40 12/09Rev. C to Rev. D Updated Format .................................................................. Universal Changes to Table 5 ............................................................................ 9 Updated Outline Dimensions ....................................................... 39 2/00Rev. B to Rev. C Rev. E Page 2 of 40