AD7124-4 Σ-Δ ADC IC Chip

AD7124-4(4-Channel, Low Noise, Low Power, 24- Bit,Sigma-Delta ADC with PGA and Reference)

Introduction

The AD7124-4 is a low power, low noise, completely integrated analog front end for high precision measurement applications.The device contains a low noise, 24-bit Σ-Δ analog-to- digital converter(ADC), and can be configured to have four differential inputs or seven single-ended or pseudo differential inputs. The on-chip low gain stage ensures that signals of small amplitude can be interfaced directly to the ADC.

One of the major advantages of the AD7124-4 is that it gives the user the flexibility to employ one of three integrated power modes. 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 that the user has the highest degree of flexibility.

The device operates with a single analog power supply from 2.7 V to 3.6 V or a dual 1.8 V power supply. The digital supply has a range of 1.65 V to 3.6 V. It is specified for a temperature range of -40°C to +125°C. The AD7124-4 is housed in a 32-lead LFCSP package and a 24-lead TSSOP package.

Feature

• 3 power modes
• RMS noise
  – Low power: 24 nV rms at 1.17 SPS, gain= 128 (255 μA typical)
  – Mid power: 20 nV rms at 2.34 SPS, gain = 128 (355 μA typical)
  – Full power: 23 nV rms at 9.4 SPS, gain = 128 (930 μA typical)
• Up to 22 noise free bits in all power modes (gain = 1)
• Output data rate
  – Full power: 9.38 SPS to 19,200 SPS
  – Mid power: 2.34 SPS to 4800 SPS
  – Low power: 1.17 SPS to 2400 SPS
• Rail-to-rail analog inputs for gains > 1
• Simultaneous 50 Hz/60 Hz rejection at 25 SPS (single cycle settling)
• Diagnostic functions (which aid safe integrity level (SIL) certification)
• Crosspoint multiplexed analog inputs
  – 4 differential/7 pseudo differential inputs
• Programmable gain (1 to 128)
• Band gap reference with 10 ppm/°C drift maximum (70 μA)
• Matched programmable excitation currents
• Internal clock oscillator
• On-chip bias voltage generator
• Low-side power switch
• General-purpose outputs
• Multiple filter options
• Internal temperature sensor
• Self and system calibration
• Sensor burnout detection
• Automatic channel sequencer
• Per channel configuration
• Power supply: 2.7 V to 3.6 V and ±1.8V
• Independent interface power supply
• Power-down current: 5 μA maximum
• Temperature range: -40°C to +125°C
• 32-lead LFCSP/24-lead TSSOP
• 3-wire or 4-wire serial interface
  – SPI, QSPI, MICROWIRE, and DSP compatible
  – Schmitt trigger on SCLK
• ESD: 4 kV

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