ADI AD7124-8BCPZ

The AD7124-8 is a low power, low noise, complete analog front end for high precision measurement applications. The device integrates a low noise 24-bit Σ-Δ ADC, configurable to provide 8 differential inputs or 15 single-ended or pseudo-differential inputs. The on-chip low noise gain stage means that signals can be applied directly to the ADC.

One of the key benefits of the AD7124-8 is the flexibility it offers users through three integrated power modes. Power consumption, output data rate range, and RMS noise can be tailored through the selected power mode. The device also provides multiple filter options to ensure maximum flexibility for the user.

The AD7124-8 achieves simultaneous 50 Hz and 60 Hz rejection at an output data rate of 25 SPS (single cycle settling), and greater than 80 dB rejection at lower output data rates.

The AD7124-8 offers the highest level of signal chain integration. The device integrates a precision low noise, low drift internal bandgap reference, and also accepts a buffered external differential reference. Other key integrated features include programmable low drift excitation current sources, burnout currents, and a bias voltage generator that can set the common-mode voltage of any channel to AVDD/2. A low-side power switch allows users to power down bridge sensors between conversions, ensuring absolute minimum system power consumption. The device also allows users to operate with an internal or external clock.

An on-chip channel sequencer allows multiple channels to be enabled simultaneously, with the AD7124-8 sequentially performing conversions on each enabled channel, simplifying communication with the device. Up to 16 channels can be enabled at any time, with analog input or diagnostic functions such as supply check or reference check. This unique feature allows diagnostics and conversions to be interleaved. The AD7124-8 also supports independent configuration per channel. The device supports 8 configurations or setups. Each configuration includes gain, filter type, output data rate, buffering, and reference source. Users can assign any setup to any channel.

The AD7124-8 also integrates extensive diagnostic functions as part of a comprehensive feature set. These diagnostics include cyclic redundancy check (CRC), signal chain check, and serial interface check, providing a more robust solution. These diagnostic functions reduce the external components required to implement diagnostics, thereby reducing board space requirements, design time, and cost. Failure Mode, Effects, and Diagnostic Analysis (FMEDA) for typical applications per IEC 61508 indicates a Safe Failure Fraction (SFF) greater than 90%.

The device operates from a 2.7 V to 3.6 V single analog supply or 1.8 V dual supplies. The digital supply range is 1.65 V to 3.6 V. The device is rated over a temperature range of −40°C to +105°C. The AD7124-8 is available in a 32-lead LFCSP package.

• RMS Noise:
  • Low Power: 24 nV rms (1.17 SPS), Gain = 128 (typical 255 μA)
  • Mid Power: 20 nV rms (2.34 SPS), Gain = 128 (typical 355 μA)
  • Full Power: 23 nV rms (9.4 SPS), Gain = 128 (typical 930 μA)
• Noise-free resolution up to 22 bits (Gain = 1) in all power modes
• Multiple filter options
• Internal temperature sensor
• Self-calibration and system calibration
• Sensor open-circuit detection
• Automatic channel sequencer
• Independent per-channel configuration
• Supply voltage: 2.7 V to 3.6 V and ±1.8 V
• Separate interface supply
• Shutdown mode current: 5 μA (maximum)
• Temperature range: -40°C to +105°C
• 32-lead LFCSP
• 3-wire or 4-wire serial interface compatible with SPI, QSPI, MICROWIRE, and DSP
• Schmitt trigger on SCLK pin

• Temperature measurement
• Pressure measurement
• Industrial process control
• Instrumentation
• Smart transmitters