Features and Benefits
- 8-/10-Channel, High Resolution Σ-Δ ADCs
- 16-Bit Resolution
- Single Conversion Cycle Setting
- Programmable Gain Front End
- Simultaneous 50 Hz and 60 Hz Rejection
- VREF Select™ Allows Absolute and Ratiometric Measurement Capability
- Operation Can Be Optimized for Analog Performance (CHOP = 0) or
Channel Throughput (CHOP= 1)
The AD7708 / AD7718 are complete analog front-ends for low frequency measurement applications. The AD7718 contains a 24-bit sigma delta ADC with PGA and can be configured as 4/5 fully-differential input channels or 8/10 pseudo-differential input channels. Two pins on the device are configurable as analog inputs or reference inputs. The AD7708 is a 16-bit version of the AD7718. Inputs signal ranges from 20mV to 2.56V can be directly converted using these ADCs. Signals can be converted directly from a transducer without the need for signal conditioning.
The device operates from a 32 kHz crystal with an on-board PLL generating the required internal operating frequency. The output data rate from the part is software programmable. The peak-to-peak resolution from the part varies with the programmed gain and output data rat
The part operates from a single 3 V or 5 V supply. When operating from 3 V supplies, the power dissipation for the part is 3.84 mW typ. Both parts are pin-for-pin compatible allowing an upgradable path from 16 to 24 bits without the need for hardware modifications. The AD7708 / AD7718 are housed in 28-lead SOIC and TSSOP packages
- Industrial Process Control
- Pressure Transducers
- Portable Instrumentation
- Smart Transmitters
Product Lifecycle Production
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.
Evaluation Kits (1)
The EVAL-AD7708EBZ is a fully featured evaluation Board for the AD7708. The evaluation board can be connected to a PC via the parallel port. Software is provided enabling the user to perform detailed analysis of the ADC's performance.
Documentation & Resources
AN-610: The PGA on Sigma-Delta ADCs (Rev. A)2/14/2015
AN-609: Chopping on Sigma-Delta ADCs (Rev. 0)2/14/2015
AN-608: Input Buffers on Sigma-Delta ADCs (Rev. 0)2/14/2015
AN-202: An IC Amplifier User’s Guide to Decoupling, Grounding, and Making Things Go Right for a Change (Rev. B)2/14/2015
AN-389: Using Sigma-Delta Converters-Part 22/14/2015
AN-388: Using Sigma-Delta Converters-Part 12/14/2015
AN-311: How to Reliably Protect CMOS Circuits Against Power Supply Overvoltaging3/8/2008
AN-607: Selecting a Low Bandwidth (<15 kSPS) Sigma-Delta ADC (Rev. E)10/12/2006
AN-615: Peak-to-Peak Resolution Versus Effective Resolution (Rev. 0)12/21/2004
AN-611: 50 Hz/60Hz Rejection on Sigma-Delta ADCs (Rev. 0)8/15/2003
AN-665: Channel Switching Using Σ-Δ ADCs (Rev. 0)8/15/2003
AN-397: Electrically Induced Damage to Standard Linear Integrated Circuits:11/18/2002
AN-283: Sigma-Delta ADCs and DACs9/24/2002
Designing Power Supplies for High Speed ADC2/1/2012
Delta-Sigma Rocks RF, As ADC Designers Jump On Jitter1/12/2006
Part 2: Circuit Suggestions Using Features and Functionality of New Sigma-Delta ADCs6/1/2002
Part 1: Circuit Suggestions Using Features and Functionality of New Sigma-Delta ADCs10/1/2001
Software & Systems Requirements
AD7708 Companion Parts
Recommended Digital Isolators
- For cost sensitive designs: ADUM7440, ADUM7441, ADUM7442.
- For process control applications: ADUM1400, ADUM1200.
- For isolated USB designs in healthcare and industrial control: ADUM4160.
- For digital isolators with integrated isolated power: ADUM5401, ADUM5402, ADUM5403.
Recommended Voltage References
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.
Sample & Buy
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Pricing displayed is based on 1-piece. The USA list pricing shown is for budgetary use only, shown in United States dollars (FOB USA per unit), and is subject to change. International prices may vary due to local duties, taxes, fees and exchange rates.