AD4195-4: 24-bit, 62.5kSPS, multichannel, low-noise precision sigma-delta ADC

The AD4195-4 offers the highest degree of signal chain integration. The device contains an internal reference and accepts two external differential references, which can be internally buffered. Other key integrated features include:
 

• Programmable gain amplifier (PGA). Due to the programmable gain (0.5 to 128), the PGA allows direct interfacing to transducers with low output amplitudes such as resistive bridges, thermocouples, and resistance temperature detectors (RTDs).
• The PGA has a wide common-mode input range, which gives designers a greater margin for widely varying input common modes.
• Low drift, well matched precision current sources. Use the excitation current sources to excite 2-, 3-, and 4-wire RTDs or bridge type sensors. Excitation current output options include 10μA, 50μA, 100μA, 250μA, 500μA, 1mA, and 1.5mA. The currents can also be added if higher currents are required.
• Use the low-side power switch (PDSW) to power down bridge sensors between conversions.
• Voltage bias for thermocouples (the VBIAS source sets the common-mode voltage of a channel to (AVDD + AVSS)/2.
• The smart sequencer allows the conversion of each enabled preconfigured channel in a predetermined order, which allows a mix of transducer, system checks, and diagnostic measurements to be interleaved. The sequencer eliminates the need for repetitive serial interface communication with the device to change configuration. Configure the 16-channels in the sequence. Each of these channels selects from eight user-defined ADC setups that allow selection of gain, filter type, output data rate, buffering, and reference source.

 
The AD4195-4 also has extensive diagnostic functionality integrated as part of its comprehensive feature set. These diagnostics include a cyclic redundancy check (CRC), signal chain checks, and serial interface checks, which lead to a more robust solution.
 
The device also offers a multitude of filter options, which ensure that the user has the highest degree of flexibility. The part contains sinc filters, which allow faster settling. In addition, the AD4195-4 offers multiple options for simultaneous 50Hz and 60Hz rejection.
 
The device operates with a single analog power supply from 4.75V to 5.25V or a bipolar 2.5V power supply. The digital supply has a range of 1.7V to 5.25V. It is specified for a temperature range of −40°C to +105°C. The AD4195-4 is housed in a 32-lead LFCSP package.
 
 
Key Features and Benefits

•  Input referred noise: 10nV at 3.8SPS, Gain = 128
• Crosspoint multiplexed analog inputs
• 4 Differential/8 Pseudodifferential inputs
• Ultra-low noise integrated PGA, gains of 0.5 to 128
• Output data rate: 3.8SPS to 62.5kSPS
• Flexible digital filters

○      Low latency sinc filters

○      Simultaneous 50Hz/60Hz rejection

• Band-gap reference with 5ppm/°C drift typical
• Internal oscillator
• Analog power supply: 4.75V to 5.25V or ±2.5V
• Digital power supply: 1.7V to 5.25V
•  Matched programmable excitation current sources
• Low-side power switches
• On-chip bias voltage generator
• Internal temperature sensor
• Four general-purpose inputs/outputs
• Internal and system calibration
• Sensor burnout detection
• Diagnostic functions
• Per channel configuration
• Flexible automatic channel sequencer
• 3- or 4-wire serial interface (Schmitt trigger on SCLK)

○      SPI, QSPI, MICROWIRE, and DSP compatible

• TDM compatible interface for data streaming
• Performance temperature range: −40°C to +105°C
• Functional temperature range: −40°C to +125°C
• Available in 32-lead 4mm x 6mm LFCSP package

 
Applications

• Industrial process control: PLC/DCS modules
• Temperature measurement
• Pressure measurement
• Medical and scientific instrumentation
• Chromatography
• Environmental monitoring
• Electrical test and measurement
• Instrumentation
• Weigh scale