AFE49I30 Ultra-Small, Integrated AFE With FIFO for Multi-Sensor Wearable, Optical Heart-Rate Monitoring and Bio-sensing

1 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 1 kHz data rate
• ECG-only mode supports up to 4 kHz data rate
• PPG signal chain:
  • System SNR up to 108-dB at 16 μA PD current
  • Low current for continuous operation on a wearable device with a typical value: 15 μA for an LED, 20 μA for the receiver
• PPG Transmitter:
  • Supports common anode LED configuration
  • 8-Bit programmable LED current with range adjustable from 25 mA to 250 mA
  • 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 4 time-multiplexed photodiode inputs
  • 2 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 255-μA
  • Individual LED offset subtraction DAC at each TIA input with 5-bit per-phase control and
    15.5-µA range
  • Close to 100 dB ambient rejection up to 10 Hz
  • Noise filtering with programmable bandwidth
  • Transimpedance Gain: 3.7 kΩ to 1 MΩ
• ECG Signal Chain
  • 1-lead ECG with RLD output for bias
  • INA gain programmable from 1.6 – 13
  • <1 µVrms input noise (in a 1-150 Hz bandwidth) at 4-kHz sample rate
  • Integrated 450 Hz Low Pass Filter
  • AC, DC lead-off detect with 3.125-100 nA 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
• 2.6-mm × 2.1-mm DSBGA, 0.4-mm pitch
• Supplies: Rx: 1.7 V-1.9 V (LDO bypass); 1.9 V-3.6 V (LDO enabled), Tx: 3 V-5.5 V, IO: 1.7-3.6 V
• Supports operation with 2 supplies - 1.8 V, 5 V

2 Applications

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