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