AFE4432 Series
Ultrasmall, ultra-low-power, high-SNR, integrated AFE for wearable optical biosensing with FIFO
Manufacturer: Texas Instruments
Catalog
Ultrasmall, ultra-low-power, high-SNR, integrated AFE for wearable optical biosensing with FIFO
Key Features
• Supports signal acquisition of up to 12 phase setsSupports up to 4 LEDs, 3 PDsFlexible allocation of LEDs, PDs in each phaseSimultaneous signal acquisition from different sensors at different data ratesAccurate, continuous PPG monitoring:Low current for continuous heart-rate monitoring on a wearable device with a typical value: 12 µA for the receiverPeak system SNR of 115 dB in 0.5-10 Hz band enables high-accuracy SpO2 measurementTransmitter:8-Bit Programmable LED current with range adjustable from 25 mA to 250 mAMode to fire two LEDs in parallel with independent per-phase current controlProgrammable LED on-time per-phaseSimultaneous support of 4 LEDs for SpO2, Multi-Wavelength HRMReceiver:Supports 3 Time-Multiplexed PD Inputs2 parallel receivers (2 sets of TIA/filter)Individual ambient offset subtraction DAC at each TIA Input with 8-bit per-phase control and range adjustable up to 255-µAIndividual LED offset subtraction DAC at each TIA input with 9-bit per-phase control and 64-µA rangeDigital ambient subtraction at ADC outputNoise filtering with programmable bandwidthTransimpedance gain: 3.7 kΩ to 1 MΩSupports external clock or internal oscillatorOption to acquire data synchronized with a system clockAutomatic cancellation of DC from Ambient, LEDFIFO with 160-sample depthSPI™ interface/ I2C interface1.9-mm × 1.8-mm DSBGA, 0.35-mm PitchSupplies: Rx:1.7 - 1.9 V, Tx: 3-5.5 VSupports signal acquisition of up to 12 phase setsSupports up to 4 LEDs, 3 PDsFlexible allocation of LEDs, PDs in each phaseSimultaneous signal acquisition from different sensors at different data ratesAccurate, continuous PPG monitoring:Low current for continuous heart-rate monitoring on a wearable device with a typical value: 12 µA for the receiverPeak system SNR of 115 dB in 0.5-10 Hz band enables high-accuracy SpO2 measurementTransmitter:8-Bit Programmable LED current with range adjustable from 25 mA to 250 mAMode to fire two LEDs in parallel with independent per-phase current controlProgrammable LED on-time per-phaseSimultaneous support of 4 LEDs for SpO2, Multi-Wavelength HRMReceiver:Supports 3 Time-Multiplexed PD Inputs2 parallel receivers (2 sets of TIA/filter)Individual ambient offset subtraction DAC at each TIA Input with 8-bit per-phase control and range adjustable up to 255-µAIndividual LED offset subtraction DAC at each TIA input with 9-bit per-phase control and 64-µA rangeDigital ambient subtraction at ADC outputNoise filtering with programmable bandwidthTransimpedance gain: 3.7 kΩ to 1 MΩSupports external clock or internal oscillatorOption to acquire data synchronized with a system clockAutomatic cancellation of DC from Ambient, LEDFIFO with 160-sample depthSPI™ interface/ I2C interface1.9-mm × 1.8-mm DSBGA, 0.35-mm PitchSupplies: Rx:1.7 - 1.9 V, Tx: 3-5.5 V
Description
AI
The AFE4432 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 4 switching light-emitting diodes (LEDs) and up to three photodiodes (PDs). The AFE has two LED drivers each with 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. Up to 12 signal phase sets can be defined, each phase set comprising a combination of LED and Ambient phases. Low noise offset DACs at the receiver inputs can be automatically controlled to cancel DC from Ambient and LED light. The current from the PDs in each phase is converted into voltage by TIAs, filtered, and then digitized using a common ADC. The ADC code can be stored in a 160-sample FIFO block. The FIFO can be read out using a SPI or I2C interface.
The AFE4432 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 4 switching light-emitting diodes (LEDs) and up to three photodiodes (PDs). The AFE has two LED drivers each with 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. Up to 12 signal phase sets can be defined, each phase set comprising a combination of LED and Ambient phases. Low noise offset DACs at the receiver inputs can be automatically controlled to cancel DC from Ambient and LED light. The current from the PDs in each phase is converted into voltage by TIAs, filtered, and then digitized using a common ADC. The ADC code can be stored in a 160-sample FIFO block. The FIFO can be read out using a SPI or I2C interface.
