Analog Devices Inc.
The AD7124-8 is a low power, low noise, completely integratedanalog front end for high precision measurement applications.The device contains a low noise, 24-bit ?-? analog-to-digitalconverter (ADC), and can be configured to have 8 differentialinputs or 15 single-ended or pseudo differential inputs. The onchiplow gain stage ensures that signals of small amplitude canbe interfaced directly to the ADC.One of the major advantages of the AD7124-8 is that it gives theuser the flexibility to employ one of three integrated powermodes. The current consumption, range of output data rates,and rms noise can be tailored with the power mode selected.The device also offers a multitude of filter options, ensuring thatthe user has the highest degree of flexibility.The AD7124-8 can achieve simultaneous 50 Hz and 60 Hzrejection when operating at an output data rate of 25 SPS (singlecycle settling), with rejection in excess of 80 dB achieved at loweroutput data rates.The AD7124-8 establishes the highest degree of signal chainintegration. The device contains a precision, low noise, lowdrift internal band gap reference and accepts an externaldifferential reference, which can be internally buffered. Otherkey integrated features include programmable low drift excitationcurrent sources, burnout currents, and a bias voltage generator,which sets the common-mode voltage of a channel to AVDD/2.The low-side power switch enables the user to power downbridge sensors between conversions, ensuring the absoluteminimal power consumption of the system. The device alsoallows the user the option of operating with either an internalclock or an external clock.The integrated channel sequencer allows several channels to beenabled simultaneously, and the AD7124-8 sequentially convertson each enabled channel, simplifying communication with thedevice. As many as 16 channels can be enabled at any time, achannel being defined as an analog input or a diagnostic suchas a power supply check or a reference check. This uniquefeature allows diagnostics to be interleaved with conversions.The AD7124-8 also supports per channel configuration. Thedevice allows eight configurations or setups. Each configurationconsists of gain, filter type, output data rate, buffering, andreference source. The user can assign any of these setups on achannel by channel basis.The AD7124-8 also has extensive diagnostic functionalityintegrated as part of its comprehensive feature set. Thesediagnostics include a cyclic redundancy check (CRC), signalchain checks, and serial interface checks, which lead to a morerobust solution. These diagnostics reduce the need for externalcomponents to implement diagnostics, resulting in reducedboard space needs, reduced design cycle times, and cost savings.The failure modes effects and diagnostic analysis (FMEDA) of atypical application has shown a safe failure fraction (SFF) greaterthan 90% according to IEC 61508.The device operates with a single analog power supply from 2.7 Vto 3.6 V or a dual 1.8 V power supply. The digital supply has arange of 1.65 V to 3.6 V. It is specified for a temperature rangeof ?40?C to +125?C. The AD7124-8 is housed in a 32-leadLFCSP package.Note that, throughout this data sheet, multifunction pins, suchas DOUT/RDY, are referred to either by the entire pin name orby a single function of the pin, for example, RDY, when onlythat function is relevant.Applications Temperature measurement Pressure measurement Industrial process control Instrumentation Smart transmitters