GENERAL DESCRIPTION
The ADPD7000 is a highly integrated analog front end (AFE)
designed for measuring various vital signals.
The optical channel is designed as an optical transceiver, stimulating
up to eight light emitting diodes (LEDs) and measuring the
return signal on up to four separate current inputs. The signal chain
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.
The electrocardiography (ECG) signal acquisition is designed to
support low noise, diagnostic level measurement in the presence
of a variety of interferers. The ECG signal chain has a number
of complementary features supporting ECG measurement, such as
driven reference for common-mode rejection and lead off detection
to identify a fallen electrode.
The body impedance analysis (BIA) signal chain is designed for
body impedance measurement with a configurable excitation path
and measurement path. A 12-bit digital-to-analog converter (DAC)
is used in the excitation path to generate the sinusoid wave and
high precision measurement, with configurable filters used to measure
the body response of the stimulus.
The electrodermal activity (EDA) signal chain is designed for electrodermal
activity. By multiplexing BIA and ECG peripheral circuits,
the ADPD7000 supports high precision AC and DC measurement
with 1 nS resolution.
The data output and functional configuration use a serial port interface
(SPI) on the ADPD7000. The control circuitry includes flexible
LED signaling and synchronous detection, digital filters, digital wave
generators, and configurable filters.

FEATURES
► Multimodal analog front end
► Optical channel
► 4 input channels with multiple operation modes for various
sensor measurements
► 4-channel processing with simultaneous sampling
► 12 programmable time slots for synchronized sensor measurements
► Flexible input multiplexing to support single-ended sensor
measurements
► 8 LED drivers, 2 of which can be driven simultaneously
► Flexible sampling rate from 0.004 Hz to 9 kHz using internal
oscillators
► AC ambient light rejection: 78 dB up to 100 Hz
► 400 mA total LED peak drive current
► Individual ambient cancellation DAC at TIA input with 9-bit
control up to 300 μA
► Individual LED DC cancellation DAC at TIA input with 7-bit
control up to 190 μA
► ECG channel
► <1 μV RMS RTI noise at diagnosis bandwidth
► High input impedance 20 GΩ
► Accepts up to ±1.2 V of DC differential input range
► CMRR: 115 dB
► Flexible 4 electrode configurations to support various applications
► Both AC lead off detection and DC lead off detection
► Support always on, low power, lead on detection
► BIA channel
► Low power, high accuracy excitation path
► Configurable excitation frequency up to 250 kHz
► Sine wave excitation with a 12-bit DAC
► High accuracy with large imbalance contact impedance ≤20
kΩ
► Configurable receive filters with low noise design
► Complex impedance measurement engine
► Integrated current-limit resistors
► EDA channel
► Support both voltage excitation and current excitation
► 10 kΩ to100 MΩ measurement range with 1 nS resolution
► DFT and decimation for high accuracy measurement result
► SPI communications supported
► 704-byte FIFO

APPLICATIONS
► Wearable health and fitness monitors: heart rate, heart rate
variability, saturation level of pulse oxygen, body impedance
analysis, hydration analysis, and cuff-less noninvasive blood
pressure
► Clinical patient monitors: small bed-side patient, home portable
patient, and small remote patient
► Industrial monitoring: particle, aerosol, and gas detection
► Conductivity detection