Features and Benefits
- 16 Bits Resolution with No Missing 16-Bit Codes
- Throughput: 500 kSPS
- INL: ±0.4 LSB Typ, ±1.5 LSB Max
- S/(N+D): 95 dB @ 20 kHz
- Power Dissipation:
4 mW @ 100 kSPS
4 µW @ 100 SPS
- True Differential Analog input range: ±VREF 0 V to VREF with VREF up to VDD on Both Inputs
- No Pipeline Delay
- Single Supply 5V Operation with 1.8V to 5 V Logic Interface
- Multiple ADCs Daisy Chain, with BUSY Indicator
- Serial Interface SPI/QSPI/Wire/DSP compatible
- µSOIC Package (µSO8 Size) and 3 mm by 3 mm QFN (LFCSP) (SOT23 size)
- Pin-to-Pin Compatible with the AD7685, AD7686, AD7687
The AD7688 is a 16-bit, 500 kSPS, charge redistribution successive-approximation Analog-to-Digital Converter which operates from a single 5V power supply, VDD. It contains a very low power high-speed 16-bit sampling ADC with no missing codes, an internal conversion clock and a versatile serial interface port. The part also contains a low noise, wide bandwidth, very short aperture delay track/hold circuit. On the CNV rising edge, it samples the voltage difference between IN+ and IN- pins. The voltages on these pins usually swing in opposite phase between 0 V to REF. The reference voltage REF is applied externally and can be set up to the supply voltage.
Its power scales linearly with throughput.
The SPI compatible serial interface also features the ability, using the SDI input, to “Daisy chain” several ADCs on a single 3 wire bus and provides an optional Busy indicator. It is compatible with 1.8 V, 2.5 V, 3 V or 5 V logic using the separate supply VIO.
The AD7688 is housed in a 10-lead µSOIC or 10-lead QFN (Chip Scale package) with operation
- Battery Powered Equipment
- Medical instruments
- Mobile communications
- Personal digital assistants
- Data Acquisition
- Medical Instruments
- Process Control
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 (2)
The PMOD-compatible evaluation/prototyping board is a small form factor, low-cost analog-to-digital conversion option. When prototyping, this board is used in conjunction with your favorite MCU or FPGA development board which has the SPI PMOD peripheral connector. Direct electrical and physical connection will enable you to quickly develop software for your system.
This board can also be operated as an evaluation board using the System Demonstration Platform (EVAL-SDP-CB1Z) and an adaptor board (SDP-PMD-IB1Z). When operated with the System Demonstration Platform, a LabView software GUI is provided enabling the user to perform analysis of the ADC's performance.
The EVAL-AD7688SDZ is a fully featured evaluation kit for the AD7688. This board operates in standalone mode or in conjunction with the System Development Platform, EVAL-SDP-CB1Z . When operated with the System Development Platform software is provided enabling the user to perform detailed analysis of the ADC's performance. This software includes the technical note describing the operation and set up of the evaluation board in standalone operation or when operated with the System Development Platform . When operated in standalone mode the ADZS-BRKOUT-EX3 break out board is recommended for access to various control pins.
Documentation & Resources
The Data Conversion Handbook, 20051/2/2005
SAR ADC & Driver Quick-Match Guide9/13/2013
Software & Systems Requirements
Tools & Simulations
Precision ADC Driver Tool
The Precision ADC Driver Tool is a web application that simulates the performance of precision ADC and driver combinations. Potential issues with driver selection, kickback settling, and distortion are flagged, and design tradeoffs can be quickly evaluated. Simulations and calculations include system noise, distortion, and settling of the ADC input
AD7685 IBIS Models
AD7688 Companion Parts
Recommended Digital Isolators
- For SPI Interface, low power, 5.0 kVrms isolation: ADUM4401.
- For SPI Interface, smallest package, low voltage I/O (1.8 V to 5.5 V): ADUM3481.
- For SPI Interface, enhanced system-level ESD performance, 2.5 kVrms isolation: ADUM3401.
- For SPI Interface, lowest power, 2.5 kVrms isolation: ADUM1401.
Recommended Driver Amplifiers
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.