Multimodal Sensor Front End

The ADPD4000/ADPD4001 operate as a complete multimodal sensor front end, stimulating up to eight LEDs and measuring the return signal on up to eight separate current inputs. Twelve time slots are available, enabling 12 separate measurements per sampling period.

The data output and functional configuration utilize an I2C interface on the ADPD4001 or a serial port interface (SPI) on the ADPD4000. The control circuitry includes flexible LED signaling and synchronous detection. The devices use a 1.8 V analog core and 1.8 V/3.3 V compatible digital input/output (I/O).

The analog front end (AFE) rejects signal offsets and corruption from asynchronous modulated interference, typically from ambient light, eliminating the need for optical filters or externally controlled dc cancellation circuitry. Multiple operating modes are provided, enabling the ADPD4000/ADPD4001 to be a sensor hub for synchronous measurements of photodiodes, biopotential electrodes, resistance, capacitance, and temperature sensors.

The ADPD4000/ADPD4001 are available in a 3.11 mm × 2.14 mm, 0.4 mm pitch, 33-ball WLCSP and 35-ball WLCSP.

For more information about the ADPD4000/ADPD4001, contact Analog Devices, Inc., at opticalsensors@analog.com.

Applications

* Wearable health and fitness monitors: heart rate monitors (HRMs), heart rate variability (HRV), stress, blood pressure estimation, SpO2, hydration, body composition

* Industrial monitoring: CO, CO2, smoke, and aerosol detection

* Home patient monitoring

* Multimodal analog front end

* 8 input channels with multiple operation modes to accommodate the following measurements: PPG, ECG, EDA, impedance, and temperature

* Dual channel processing with simultaneous sampling

* 12 programmable time slots for synchronized sensor measurements

* Flexible input multiplexing to support differential and single-ended sensor measurements

* 8 LED drivers, 4 of which can be driven simultaneously