TI AFE4950YBGT

The AFE4950 device is an analog front-end (AFE) for synchronous acquisition of PPG and ECG signals. This device can also be used in optical biosensing applications such as heart rate monitoring (HRM) and peripheral capillary oxygen saturation (SpO2) measurement. The ECG signal chain supports two-electrode and three-electrode configurations and features an integrated right-leg drive (RLD) buffer. The ECG signal chain can also be used to continuously monitor the impedance between a pair of electrodes with lower power consumption.

• Simultaneous and synchronous acquisition of up to 24 PPG and single-lead ECG signals
• Flexible 8 LED, 4 PD assignment per phase
• Single-lead ECG acquisition at frequencies up to 2kHz
• RLD output for driving third electrode
• Input noise: 0.7μVrms
• Supports differential DC offset voltage up to ±0.65V and common-mode range of ±0.55V
• Programmable INA gain: 11, 21
• High-pass filter with fast saturation recovery
• Integrated 300Hz anti-aliasing low-pass filter
• AC/DC lead-off detection: 2.9nA to 92.5nA
• Low-power continuous lead-on detection
• Continuous low-power impedance monitoring between 2 electrodes
• 7MΩ range
• 300Ω noise over 620kΩ
• 8-bit programmable LED current, adjustable range 25mA to 250mA
• Parallel dual-LED illumination mode
• Supports 8 LEDs in common-anode configuration for SpO2, multi-wavelength HRM
• 2 parallel receivers (dual TIA/filter sets)
• Supports 4-channel TDM photodiode input to each receiver
• 8-bit ambient offset subtraction at each TIA input (256μA range)
• 8-bit LED offset subtraction DAC (64μA range)
• Automatic ambient cancellation and dynamic LED DC cancellation at TIA input
• Ambient rejection approaching 100dB at frequencies up to 10Hz
• Noise filtering with programmable bandwidth
• Transimpedance gain: 3.7kΩ to 1MΩ
• System SNR up to 109dB at 16μA PD current
• Low operating current for continuous wearable operation, typical values: LED 15μA, receiver 20μA
• External clock and internal oscillator modes
• Data acquisition synchronized to system master clock
• FIFO with 256 sample depth
• SPI, I²C interface: pin-selectable
• 2.6mm×2.5mm DSBGA package, 0.4mm pitch
• Power supply — Rx: 1.7V - 1.9V (LDO bypass); 1.9V - 3.6V (LDO enabled), Tx: 3V - 5.5V, IO: 1.7 - RX_SUP

• Optical heart rate monitoring (HRM) for wearables and hearables
• High-performance ECG signal acquisition
• Simultaneous PPG and ECG monitoring for blood pressure estimation
• Heart rate variability (HRV) analysis
• Pulse oximetry (SpO₂) measurement