AD7798 Datasheet | Analog Devices

FEATURES RMS noise: 27 n V at 4.17 Hz (AD7799) 65 n V at 16.7 Hz (AD7799) 40 n V at 4.17 Hz (AD7798) 85 n V at 16.7 Hz (AD7798) Current: 380 µA typical Power-down: 1 µA maximum Low noise, programmable gain, instrumentation amp Update rate: 4.17 Hz to 470 Hz 3 differential inputs 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 - 40°C to +105°C temperature range Independent interface power supply 16-lead TSSOP package INTERFACE 3-wire serial SPI®, QSPI™, MICROWIRE™, and DSP patible Schmitt trigger on SCLK 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 FUNCTIONAL BLOCK DIAGRAM GND AVDD REFIN(+) REFIN(- ) AD7798/AD7799 REFERENCE DETECT AIN1(+) AIN1(- ) AIN2(+) AIN2(- ) AIN3(+)/P1 AIN3(- )/P2 AVDD IN-AMP Σ-Δ ADC GND GND INTERNAL CLOCK Figure 1. SERIAL INTERFACE AND CONTROL LOGIC AD7798: 16-BIT AD7799: 24-BIT DOUT/RDY DIN SCLK CS DVDD GENERAL DESCRIPTION The AD7798/AD7799 are low power, low noise, plete analog front ends for high precision measurement applications. The AD7798/AD7799 contains a low noise, 16-/24-bit ∑-∆ 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 n V for the AD7799 and 40 n V 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...