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Texas Instruments AFE49I30 Ultra-Small Integrated Analog Front End

Texas Instruments AFE49I30 Ultra-Small Integrated Analog Front End (AFE) is an AFE for optical bio-sensing/PPG and ECG measurement applications. The Texas Instruments AFE49I30 supports up to six switching light-emitting diodes (LEDs) and up to four photodiodes. Up to 24 signal phases can be defined and the PPG or ECG signals can be acquired from each phase in a synchronized manner.

Features

  • Supports signal acquisition of up to 24 phases
  • Flexible allocation of 6 LED, 4 PD in each PPG phase
  • Synchronized PPG/ECG signal acquisition with each phase configurable as PPG or ECG and at different data rates
  • Synchronized PPG/ECG supports up to 1kHz data rate
  • ECG-only mode supports up to 4kHz data rate
  • PPG signal chain
    • System SNR up to 108dB at 16µA PD current
    • Low current for continuous operation on a wearable device with a typical value (15µA for an LED, 20µA for the receiver)
  • PPG Transmitter
    • Supports common anode LED configuration
    • 8-bit programmable LED current with range adjustable from 25mA to 250mA
    • Mode to fire two LEDs in parallel with independent per-phase current control
    • Programmable LED on-time per-phase
    • Simultaneous support of 6 LEDs for SpO2, HRM, or multi-wavelength HRM
  • PPG Receiver
    • Supports four time-multiplexed photodiode inputs
    • Two parallel receivers to sample two PD channels simultaneously
    • Individual ambient offset subtraction DAC at each TIA Input with 8-bit per-phase control and range adjustable up to 255µA
    • Individual LED offset subtraction DAC at each TIA input with 5-bit per-phase control and 15.5µA range
    • Close to 100dB ambient rejection up to 10Hz
    • Noise filtering with programmable bandwidth
    • 3.7kΩ to 1MΩ transimpedance gain
  • ECG Signal Chain
    • 1-lead ECG with RLD output for bias
    • INA gain programmable from 1.6 – 13
    • < 1µVrms input noise (in a 1-150Hz bandwidth) at 4kHz sample rate
    • Integrated 450Hz Low Pass Filter
    • AC, DC lead-off detect with 3.125-100nA current and programmable interrupt
  • Supports external clock and internal oscillator modes
  • Option to acquire data synchronized with a system master clock
  • Automatic cancellation of DC from ambient, LED
  • FIFO with 128-sample depth
  • I2C interface
  • 2.6mm × 2.1mm DSBGA, 0.4mm pitch
  • Supplies
    • Rx
      • 1.7V-1.9V (LDO bypass)
      • 1.9V-3.6V (LDO enabled)
    • Tx
      • 3V-5.5V, IO: 1.7-3.6V
  • Supports operation with two supplies - 1.8V, 5V

Applications

  • ECG on a wearable device
  • Optical heart-rate monitoring (HRM) and Heart-rate variability (HRV) for wearables, hearables
  • Synchronized PPG, ECG for PTT-based blood pressure
  • Pulse oximetry (SpO2) measurements
  • Maximum oxygen consumption (VO2 max)

Simplified Schematic

Schematic - Texas Instruments AFE49I30 Ultra-Small Integrated Analog Front End
Opublikowano: 2020-07-10 | Zaktualizowano: 2024-06-28