Multi-channel micro-volt absolute accuracy readout ASIC for thermocouples and oxygen sensors

Multi-channel micro-volt absolute accuracy readout ASIC for thermocouples and oxygen sensors

The ASIC is a fully integrated, high performance (16 bit) sensor Analog Front End (AFE) for high absolute accuracy measurements targeted for remote sensor applications in harsh environments. It is ideally suited for thermocouple and electrochemical gas sensor measurements. An accurate internal temperature sensor is present to enable temperature dependent digital post processing of offset and gain errors.

FEATURES

  • Single-chip, absolute accuracy measurement solution
  • Long distance autonomous communication in remote and harsh environments up to 100m
  • No external reference voltage required: Absolute on-chip reference voltage accuracy: 0.19%
  • Selectable input range: -18.5mV to +18.5mV (type I),  -750mV to 400mV (type II)
  • Absolute accuracy: 15uV (type I) to 2.5mV (type II)
  • Resolution: 0.78uV (type I) to 37.1uV (type II)
  • 16-bit Sigma-Delta ADC
  • Sample rate: 100Hz/channel
  • Differential inputs: 4 channels
  • Internal temperature sensor resolution: 0.09°C
  • Communication: 2-wire (I-mode over supply lines) or 3-wire (supply and data line)
  • User-programmable 64-bit OTP (ID number)
  • Accurate burn-out function (open wire detection):
    • Programmable 50nA to 5uA
    • Error-free detection via GP pin
  • Sensor cross-talk insensitivity by time-multiplexed separate sensor bias
  • Sensor negative voltage bias by on-chip reference
  • SPI interface
  • Operating range: -20 to +80°C
  • 2kV HBM ESD
  • Low cost QFN24 (5x5mm)
  • 0.35um CMOS

CHIP LAYOUT