TI AFE4404YZPR

The AFE4404 is an analog front-end (AFE) for optical bio-sensing applications, such as heart-rate monitoring (HRM) and saturation of peripheral capillary oxygen (SpO2). The device supports three switching light-emitting diodes (LEDs) and a single photodiode. The current from the photodiode is converted into voltage by the transimpedance amplifier (TIA) and digitized using an analog-to-digital converter (ADC). The ADC code can be read out using an I²C interface. The AFE also has a fully integrated LED driver with a 6-bit current control. The device has a high dynamic range transmit and receive circuitry that helps with the sensing of very small signal levels.

• Transmitter:
  • Supports Common Anode LED Configuration
  • Dynamic Range: 100 dB
  • 6-Bit Programmable LED Current to 50 mA (Extendable to 100 mA)
  • Programmable LED On-Time
  • Simultaneous Support of 3 LEDs for Optimized SpO2, HRM, or Multi-Wavelength HRM
• Receiver:
  • 24-Bit Representation of the Current Input from a Photodiode in Twos Complement Format
  • Individual DC Offset Subtraction DAC at TIA Input for Each LED and Ambient Phase
  • Digital Ambient Subtraction at ADC Output
  • Programmable Transimpedance Gain: 10 kΩ to 2 MΩ
  • Dynamic Range: 100 dB
  • Average Current Less Than 200 μA for PPG Signal Acquisition
• Pulse Frequency: 10 SPS to 1000 SPS

• Optical Heart-Rate Monitoring (HRM)
• Heart-Rate Variability (HRV)
• Pulse Oximetry (SpO2 Measurement)
• VO2 Max
• Calorie Expenditure