AD7798 3-Channel, Low Noise, Low Power, 16-Bit, Sigma Delta ADC with On-Chip In-Amp

The AD7798/AD7799 are low power, low noise, complete analog front ends for high precision measurement applications. The AD7798/AD7799 contains a low noise, 16-/24-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 27 nV for the AD7799 and 40 nV for the AD7798 when the update rate equals 4.17 Hz.

On-chip features include a low-side power switch, reference detect, programmable digital output pins, burnout currents, and an internal clock oscillator. 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. The AD7798 consumes a current of 300 μA typical, whereas the AD7799 consumes 380 μA typical. Both devices are housed in a 16-lead TSSOP package.

Applications

Weigh scales
Pressure measurement
Strain gauge transducers
Gas analysis
Industrial process control
Instrumentation
Portable instrumentation
Blood analysis
Smart transmitters
Liquid/gas chromotography 6-digit DVM

Features and Benefits

RMSnoise:
27 nV at 4.17 Hz (AD7799)
65 nV at 16.7 Hz (AD7799)
40 nV at 4.17 Hz (AD7798)
85 nV at 16.7 Hz (AD7798)
Current: 380 μA typical
Power-down: 1 μA maximum
Update rate: 4.17 Hz to 470 Hz 3 differential inputs
Low noise, programmable gain, instrumentation amp

Internal clock oscillator
Simultaneous 50 Hz/60 Hz rejection
Reference detect
Low-side power switch
Programmable digital outputs
Burnout currents
Power supply: 2.7 V to 5.25 V

Analog to Digital Converters

A/D Converters

Design Tools

AD7785/AD7790/AD7791/AD7792/AD7793/AD7794/AD7795/AD7796/AD7797/AD7798/AD7799 Digital Filter Model .XLS

Reference Designs

Data Sheets

Document	note
AD7798/AD7799: 3-Channel, Low Noise, Low Power, 16-/24-Bit, Sigma Delta ADC with On-Chip In-Amp Data Sheet (Rev. B)	PDF 890 kB

Application Notes

Document	note
AN-202: An IC Amplifier User’s Guide to Decoupling, Grounding, and Making Things Go Right for a Change (Rev. B)	PDF 76.97 K
AN-389: Using Sigma-Delta Converters-Part 2	PDF 590 kB
AN-388: Using Sigma-Delta Converters-Part 1	PDF 590 kB
AN-347: Shielding and Guarding	PDF 688 kB
AN-968: Current Sources: Options and Circuits (Rev. 0)	PDF 131 kB
AN-311: How to Reliably Protect CMOS Circuits Against Power Supply Overvoltaging	PDF 217 kB
AN-607: Selecting a Low Bandwidth (<15 kSPS) Sigma-Delta ADC (Rev. E)	PDF 222 kB
AN-615: Peak-to-Peak Resolution Versus Effective Resolution (Rev. 0)	PDF 70 kB
AN-101: Cross Plot Generator Allows Quick A/D Converter Evaluation	PDF 280 kB
AN-397: Electrically Induced Damage to Standard Linear Integrated Circuits:	PDF 149 kB
AN-283: Sigma-Delta ADCs and DACs	PDF 1699 kB