GENERAL DESCRIPTION
The ADPD4200 operates as a complete multimodal sensor front
end, stimulating up to four light emitting diodes (LEDs) and measuring
the return signal on up to four separate current inputs. Twelve
time slots are available, enabling 12 separate measurements per
sampling period.
The data output and functional configuration utilize a serial port
interface (SPI) on the ADPD4200. The control circuitry includes
flexible LED signaling and synchronous detection. The device uses
a 1.8 V analog core and 1.8 V or 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 ADPD4200 to be a sensor hub for synchronous
measurements of photodiodes, biopotential electrodes, resistance,
capacitance, and temperature sensors.
The ADPD4200 is available in a 2.619 mm × 1.804 mm, 0.40 mm
pitch, 24-ball WLCSP.
Analog Devices is in the process of updating documentation to
provide terminology and language that is culturally appropriate. This
is a process with a wide scope and will be phased in as quickly as
possible. Thank you for your patience.

FEATURES
► Multimodal analog front end
► 4 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 singleended
sensor measurements
► 4 LED drivers, which can be driven simultaneously
► Flexible sampling rate from 0.004 Hz to 9 kHz using internal oscillators
► On-chip digital filtering
► SNR: 105 dB (100 kΩ TIA gain, 100 Hz ODR, 80 pulses, CPD =
70 pF, 0.5 Hz to 10 Hz bandwidth)
► AC ambient light rejection: 60 dB up to 1 kHz
► 400 mA total LED peak drive current
► Total system power dissipation: 30 μW (combined LED and AFE
power), continuous PPG measurement at 75 dB SNR, 25 Hz
ODR, 100 nA/mA CTR
► SPI communications supported
► 512-byte FIFO size

APPLICATIONS
► Wearable health and fitness monitors: heart rate monitors
(HRMs), heart rate variability (HRV), stress, blood pressure estimation,
SpO2, hydration, and body composition
► Industrial monitoring: CO, CO2, smoke, and aerosol detection
► Home patient monitoring