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AFE4420

ACTIVE

Ultra-small integrated AFE with FIFO for multisensor wearable optical heart-rate monitoring

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Data sheet

AFE4420

ACTIVE
Data sheet Order now

Product details

Applications Optical-HRM Number of input channels 4 Resolution (bps) 22 Number of LEDs 4 Interface type I2C Operating temperature range (°C) -40 to 85 Rating Catalog
Applications Optical-HRM Number of input channels 4 Resolution (bps) 22 Number of LEDs 4 Interface type I2C Operating temperature range (°C) -40 to 85 Rating Catalog
DSBGA (YZ) 30 4.8 mm² 2.4 x 2
  • Supports signal acquisition of up to 16 phases
  • Flexible allocation of LEDs and PDs in each phase
  • Accurate, continuous heart-rate monitoring:
    • Up to 100-dB dynamic range
    • Low current for continuous operation on a wearable device with a typical value
      • 15 µA for an LED, 20 µA for the receiver
  • Transmitter:
    • Supports common anode LED configuration
    • 8-Bit programmable LED current with range adjustable from 50 mA to 200 mA
    • Mode to fire two LEDs in parallel
    • Programmable LED on-time
    • Simultaneous support of 4 LEDs for optimized SpO2, HRM, or multi-wavelength HRM
    • Programmable control signals to extend operation to 8 LEDs using external SPDT switches
  • Receiver:
    • Supports 4 time-multiplexed photodiode inputs
    • Individual DC offset subtraction DAC at TIA input for each LED, ambient with 7-bit control and range up to ±254 µA
    • Transimpedance gain: 10 kΩ to 2 MΩ
    • Digital ambient subtraction at ADC output to suppress ambient tones
    • Noise filtering with programmable bandwidth
  • Supports external clock and internal oscillator modes
  • Automatic ambient cancellation mode (AACM) to increase receiver dynamic range
  • Two programmable GPIO pins with flexible interrupt generation
  • FIFO with 128-sample depth
  • I2C, SPI interfaces: selectable by pin
  • Operating temperature range: –40°C to +85°C
  • 2.6-mm × 2.1-mm DSBGA, 0.4-mm pitch
  • Supplies:
    • Rx:
      • 1.7 V to 1.9 V (LDO bypass)
      • 1.9 V to 3.6 V (LDO enabled)
    • Tx: 3 V to 5.5 V
    • IO: 1.7 V to RX_SUP
  • Supports signal acquisition of up to 16 phases
  • Flexible allocation of LEDs and PDs in each phase
  • Accurate, continuous heart-rate monitoring:
    • Up to 100-dB dynamic range
    • Low current for continuous operation on a wearable device with a typical value
      • 15 µA for an LED, 20 µA for the receiver
  • Transmitter:
    • Supports common anode LED configuration
    • 8-Bit programmable LED current with range adjustable from 50 mA to 200 mA
    • Mode to fire two LEDs in parallel
    • Programmable LED on-time
    • Simultaneous support of 4 LEDs for optimized SpO2, HRM, or multi-wavelength HRM
    • Programmable control signals to extend operation to 8 LEDs using external SPDT switches
  • Receiver:
    • Supports 4 time-multiplexed photodiode inputs
    • Individual DC offset subtraction DAC at TIA input for each LED, ambient with 7-bit control and range up to ±254 µA
    • Transimpedance gain: 10 kΩ to 2 MΩ
    • Digital ambient subtraction at ADC output to suppress ambient tones
    • Noise filtering with programmable bandwidth
  • Supports external clock and internal oscillator modes
  • Automatic ambient cancellation mode (AACM) to increase receiver dynamic range
  • Two programmable GPIO pins with flexible interrupt generation
  • FIFO with 128-sample depth
  • I2C, SPI interfaces: selectable by pin
  • Operating temperature range: –40°C to +85°C
  • 2.6-mm × 2.1-mm DSBGA, 0.4-mm pitch
  • Supplies:
    • Rx:
      • 1.7 V to 1.9 V (LDO bypass)
      • 1.9 V to 3.6 V (LDO enabled)
    • Tx: 3 V to 5.5 V
    • IO: 1.7 V to RX_SUP

The AFE4420 is an analog front-end for optical bio-sensing applications, such as heart-rate monitoring (HRM) and saturation of peripheral capillary oxygen (SpO2). The device supports up to four switching light-emitting diodes (LEDs) and up to four photodiodes. Up to 16 signal phases can be defined and the signal can be acquired from each phase in a synchronized manner and stored in a 128-sample First in, First out (FIFO) block. The FIFO can be read out using either an I2C or a SPI interface. The AFE also has a fully integrated LED driver with an 8-bit current control. The device has a high dynamic range transmit-and-receive circuitry that helps with the sensing of very small signal levels.

The AFE4420 is an analog front-end for optical bio-sensing applications, such as heart-rate monitoring (HRM) and saturation of peripheral capillary oxygen (SpO2). The device supports up to four switching light-emitting diodes (LEDs) and up to four photodiodes. Up to 16 signal phases can be defined and the signal can be acquired from each phase in a synchronized manner and stored in a 128-sample First in, First out (FIFO) block. The FIFO can be read out using either an I2C or a SPI interface. The AFE also has a fully integrated LED driver with an 8-bit current control. The device has a high dynamic range transmit-and-receive circuitry that helps with the sensing of very small signal levels.

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* Data sheet AFE4420 Ultra-Small, Integrated AFE With FIFO for Multi-sensor Wearable, Optical Heart-rate Monitoring and Bio-sensing datasheet (Rev. A) PDF | HTML 30 Jul 2019

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