AFE4405AYZR

Analog Front End (AFE) Overview

The AFE4405 is an ultra-small, integrated analog front-end designed for wearable optical heart-rate monitoring and bio-sensing applications. It supports three switching LEDs and up to two photodiodes, featuring a transimpedance amplifier with gains from 10 kΩ to 2 MΩ and a 24-bit ADC representation. The device includes a 240-sample FIFO with programmable partitioning across phases. Key electrical parameters include a pulse frequency range of 5 SPS to 1000 SPS, dynamic ranges of 100 dB for both transmitter and receiver, and operating supply voltages of 2 V to 3.6 V for Rx, 3 V to 5.25 V for Tx, and 1.8 V to 3.6 V for IO.

Analog Front End (AFE) Feature Summary

• Integrated LED driver supporting common anode configuration with 8-bit programmable current control up to 50 mA (extendable to 100 mA).
• Receiver features individual DC offset subtraction DACs at the TIA input for each LED and ambient light channel.
• Includes a 240-sample depth FIFO with programmable partitioning to accommodate different sensing phases.
• Flexible clock options allowing either external clocking (4-MHz to 60-MHz) or an internal 4-MHz oscillator.

Analog Front End (AFE) Applications

• Optical Heart-Rate Monitoring (HRM) for wearables and hearables
• Heart-Rate Variability (HRV) analysis
• Pulse Oximetry (SpO2) measurements
• Maximum Oxygen Consumption (VO2 Max) tracking
• Calorie expenditure monitoring

Analog Front End (AFE) Procurement Notes

Verify the specific ordering suffix against the Package Option Addendum to confirm package type, pin count, and temperature range. Confirm RoHS compliance and lead finish details such as SNAGCU. Ensure the selected part status matches production requirements, noting that preproduction parts may have limited warranties.

Analog Front End (AFE) Selection Notes

Select based on required LED count and photodiode inputs; this device supports three LEDs and two photodiodes. Consider the power supply constraints, specifically the separate Tx (3 V to 5.25 V) and Rx (2 V to 3.6 V) rails. Evaluate the need for FIFO buffering versus real-time processing, given the 240-sample depth capability.

Analog Front End (AFE) Part Context

The AFE4405 belongs to Texas Instruments' family of integrated analog front-ends for optical bio-sensing. It is specifically optimized for wearable form factors due to its ultra-small DSBGA package dimensions of 2.6 mm × 2.1 mm. It serves as a complete solution for converting photodiode currents into digital data for health monitoring algorithms.

Analog Front End (AFE) Replacement Considerations

Public confirmed substitute part numbers are not provided in the source material. Consult the TI product folder for alternative devices within the same family if availability is an issue.

Analog Front End (AFE) FAQ

What is the maximum LED current supported by the AFE4405?

The device supports an 8-bit programmable LED current up to 50 mA, which can be extended to 100 mA.

How many photodiode inputs does the AFE4405 support?

The AFE4405 supports up to two time-multiplexed photodiode inputs.

What interfaces are available for reading data from the FIFO?

Data can be read out using either an I2C or SPI interface, which is selectable by a pin.