AD7780 Datasheet | Analog Devices

.. 24-Bit, Pin-Programmable, Ultralow Power Sigma-Delta ADC AD7780 FUNCTIONAL BLOCK DIAGRAM GND AVDD GAIN REFIN(+) REFIN(- ) AIN(+) G=1 OR 128 AIN(- ) BPDSW INTERNAL CLOCK 24-BIT Σ-Δ ADC SCLK DVDD 07945-001 Features Pin-programmable filter response Update rate: 10 Hz or 16.7 Hz Pin-programmable in-amp gain Pin-programmable power-down and reset Status function Internal clock oscillator Internal bridge power-down switch Current 115 μA typical (gain = 1) 330 μA typical (gain = 128) Simultaneous 50 Hz/60 Hz rejection Power supply: 2.7 V to 5.25 V - 40°C to +105°C temperature range Independent interface power supply Packages 14-lead, narrow body SOIC 16-lead TSSOP 2-wire serial interface (read-only device) SPI patible Schmitt trigger on SCLK DOUT/RDY FILTER PDRST Figure 1. Table 1. Parameter Output Data Rate RMS Noise P-P Resolution Settling Time Gain = 128 10 Hz 16.7 Hz 44 n V 65 n V 17.6 17.1 300 ms 120 ms Gain = 1 10 Hz 16.7 Hz 2.4 μV 2.7 μV 18.8 18.7 300 ms 120 ms APPLICATIONS Weigh scales Pressure measurement Industrial process control Portable instrumentation GENERAL DESCRIPTION The AD7780 is a plete low power front-end solution for bridge sensor products, including weigh scales, strain gages, and pressure sensors. It contains a precision, low power, 24-bit sigmadelta (Σ-Δ) ADC; an on-chip, low noise programmable gain amplifier (PGA); and an on-chip oscillator. Consuming only 330 μA, the AD7780 is particularly suitable for portable or battery-operated products where very low power is required. The AD7780 also has a power-down mode that allows the user to switch off the power to the bridge sensor and power down the AD7780 when not converting, thus increasing the battery life of the product. For ease of use, all the Features of the AD7780 are controlled by dedicated pins. Each time a data read occurs, eight status bits are appended to the 24-bit conversion. These status bits contain a pattern sequence that can be used to confirm the...