Features and Benefits
- Up to 20 bits effective resolution
- RMS noise
- 40 nV @ 4.17 Hz
- 85 nV @ 16.7 Hz
- Current: 400 µA typ
- Power-down: 1 µA max
- Low noise programmable gain instrumentation amp
- Band gap reference with 4 ppm/°C drift typ
- Update rate: 4.17 Hz to 470 Hz
- 3 differential inputs
- Simultaneous 50 Hz/60 Hz rejection
The AD7785 is a low power, low noise, complete analog front ends for high precision measurement applications. It contains a low noise 20-bit Σ-Δ ADC with three differential analog inputs. The on-chip, low noise instrumentation amplifier means that signals of small amplitude can be interfaced directly to the ADC. With a gain setting of 64, the rms noise is 40 nV when the update rate equals 4.17 Hz.
The device contains a precision low noise, low drift internal band gap reference and can also accept an external differential reference. Other on-chip features include programmable excitation current sources, burnout currents, and a bias voltage generator, the bias voltage generator being used to set the common-mode voltage of a channel to AVDD/2.
The device can be operated with either the internal clock or an external clock. The output data rate from the part is software-programmable and can be varied from 4.17 Hz to 470 Hz.
The part operates with a power supply from 2.7 V to 5.25 V. It consumes a current of 400 µA typical and is housed in 16-lead TSSOP packages.
- Thermocouple measurements
- RTD measurements
- Thermistor measurements
- Gas analysis
- Industrial process control
- Portable instrumentation
- Blood analysis
- Smart transmitters
- Liquid/gas chromatography
- 6-digit DVM
Markets and Technologies
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-AD7785EBZ is a fully featured evaluation Board for the AD7785. The evaluation board can be connected to a PC via a standard USB interface. Software is provided enabling the user to perform detailed analysis of the ADC's performance.
Please note: This Evaluation software does not run on Windows 8 or Windows 10 (USB driver is non-compliant with OS >Windows 7).
Application Notes (12)
Tools & Simulations
An interactive illustration showing the behavior of an idealized sigma-delta A/D converter.
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.
Up to two boards can be purchased through Analog.com. To order more than two, please purchase through one of our listed distributors.
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.