Integrated Analog Front End (AFE) for Heart-Rate Monitors and Low-Cost Pulse Oximeters

Integrated Analog Front End (AFE) for Heart-Rate Monitors and Low-Cost Pulse Oximeters - AFE4400

Recommended alternative parts

  • AFE4490  - The device has the SAME FUNCTIONALITY and PINOUT as the compared device but is NOT an exact equivalent.   AFE4490 is similar to the AFE4400 but has a higher performance spec


The AFE4400 is a fully-integrated analog front-end (AFE) ideally suited for pulse oximeter applications. The device consists of a low-noise receiver channel with an integrated analog-to-digital converter (ADC), an LED transmit section, and diagnostics for sensor and LED fault detection. The device is a very configurable timing controller. This flexibility enables the user to have complete control of the device timing characteristics. To ease clocking requirements and provide a low-jitter clock to the AFE4400, an oscillator is also integrated that functions from an external crystal. The device communicates to an external microcontroller or host processor using an SPI™ interface.

The device is a complete AFE solution packaged in a single, compact VQFN-40 package (6 mm × 6 mm) and is specified over the operating temperature range of 0°C to 70°C.


  • Fully-Integrated Analog Front-End for Pulse Oximeter Applications:
    • Flexible Pulse Sequencing and
      Timing Control
  • Transmit:
    • Integrated LED Driver
      (H-Bridge, Push, or Pull)
    • Dynamic Range: 95 dB
    • LED Current:
      • Programmable to 50 mA with 8-Bit Current Resolution
    • Low Power:
      • 100 µA + Average LED Current
    • Programmable LED On-Time
    • Independent LED2 and LED1 Current Reference
  • Receive Channel with High Dynamic Range:
    • 13 Noise-Free Bits
    • Low Power: < 670 µA at 3.3-V Supply
    • Integrated Digital Ambient Estimation and Subtraction
    • Flexible Receive Sample Time
    • Flexible Transimpedance Amplifier with Programmable LED Settings
  • Integrated Fault Diagnostics:
    • Photodiode and LED Open and
      Short Detection
    • Cable On and Off Detection
  • Supplies:
    • Rx = 2.0 V to 3.6 V
    • Tx = 3.0 V to 5.25 V
  • Package: Compact VQFN-40 (6 mm × 6 mm)
  • Specified Temperature Range: 0°C to 70°C

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Parametrics Compare all products in Photodiode Sensing

# Input Channels
Resolution (Bits)
Number of LEDs
Package Group
Operating Temperature Range (C)
Package Size: mm2:W x L (PKG)
AFE4400 AFE4490
1    1   
22    22   
SPI    Serial SPI   
2    2   
Catalog    Catalog   
0 to 70    -40 to 85   
40VQFN: 36 mm2: 6 x 6(VQFN)    40VQFN: 36 mm2: 6 x 6(VQFN)   
Optical biosensing    Optical biosensing