Analog Devices Inc.

Category: Data Converters

The AD7779 is an 8-channel, simultaneous sampling ADC.There are eight full Σ-Δ ADCs on chip. The AD7779 providesan ultralow input current to allow direct sensor connection. Eachinput channel has a programmable gain stage allowing gains of1, 2, 4, and 8 to map lower amplitude sensor outputs into thefull-scale ADC input range, maximizing the dynamic range ofthe signal chain. The AD7779 accepts VREF from 1 V up to 3.6 V.The analog inputs accept unipolar (0 V to VREF/GAIN) or truebipolar (±VREF/GAIN/2 V) analog input signals with 3.3 V or±1.65 V analog supply voltages. The analog inputs can beconfigured to accept true differential, pseudo differential, or singleendedsignals to match different sensor output configurations.Each channel contains an ADC modulator and a sinc3, lowlatency digital filter. An SRC is provided to allow fine resolutioncontrol over the AD7779 ODR. This control can be used inapplications where the ODR resolution is required to maintaincoherency with 0.01 Hz changes in the line frequency. The SRCis programmable through the serial port interface (SPI). TheAD7779 implements two different interfaces: a data outputinterface and SPI control interface. The ADC data outputinterface is dedicated to transmitting the ADC conversionresults from the AD7779 to the processor. The SPI interfaceis used to write to and read from the AD7779 configurationregisters and for the control and reading of data from the SARADC. The SPI interface can also be configured to output theΣ-Δ conversion data.The AD7779 includes a 12-bit SAR ADC. This ADC can be usedfor AD7779 diagnostics without having to decommission one ofthe Σ-Δ ADC channels dedicated to system measurement functions.With the use of an external multiplexer, which can becontrolled through the three general-purpose inputs/outputs pins(GPIOs), and signal conditioning, the SAR ADC can be used tovalidate the Σ-Δ ADC measurements in applications wherefunctional safety is required. In addition, the AD7779 SAR ADCincludes an internal multiplexer to sense internal nodes.The AD7779 contains a 2.5 V reference and reference buffer.The reference has a typical temperature coefficient of 10 ppm/°C.The AD7779 offers two modes of operation: high resolutionmode and low power mode. High resolution mode provides ahigher dynamic range while consuming 10.75 mW per channel;low power mode consumes just 3.37 mW per channel at areduced dynamic range specification.The specified operating temperature range is −40°C to +105°C,although the device is operational up to +125°C.APPLICATIONS Circuit breakers General-purpose data acquisition Electroencephalography (EEG) Industrial process control

$14.38 - $25.89