ADX920Q/ADX921Q/ADX922Q/ADX923Q
Low-Power, 2-Channel, 24-Bit
Analog Front-End for Biopotential Measurements
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1. FEATURES
• Three low-noise (ADX923Q) PGAs and two
high-resolution ADCs (ADX922Q and
ADX923Q)
• Input-referred noise: 8.8μV
PP
(150Hz BW, G = 6)
• Input bias current: 100pA (max)
• Data rate: 125SPS to 16kSPS
• CMRR: 117dB; THD: 109dB
• Programmable gain: 1, 2, 3, 4, 6, 8, or 12
• Supplies: unipolar or bipolar
Analog: 2.7V to 5.5V
Digital: 1.65V to 3.6V
• Built-in right leg drive amplifier, lead-off
detection, test signals
• Integrated respiration impedance
measurement (ADX922Q and ADX923Q)
• Electrode Rotation mode (ERM) to implement
time-division multiplexing LEAD-I, LEAD-II, and
LEAD-III measurements (ADX923Q)
• Integrated analog PACE measurement
(ADX921Q, ADX922Q, ADX923Q)
• Flexible power mode
High Resolution mode
High Speed mode (ADX921Q, ADX922Q,
ADX923Q)
• Built-in oscillator and reference
• Supply monitor, internal temp sensor, OSC
fault detection, overrange detection
• Flexible power-down, standby mode
• SPI™-compatible serial interface, timeout reset
• Cyclic redundancy check (CRC) on
communications, checksum
• Support ADC data FIFO for reducing polling
time of the external device to save power
• Functional safety features to support
automotive application
• Supports systems meeting IEC 60601-2-47
• Operating temperature range: –40°C to 125°C
• AEC-Q100
2. APPLICATIONS
• Medical instrumentation (ECG) including:
Patient monitoring: Holter, event, stress,
and vital signs including ECG, AED, and
telemedicine
Personal care and fitness monitors (heart
rate, respiration, and ECG)
• High-precision, simultaneous, multichannel
data acquisition
3. DESCRIPTION
The ADX92xQ devices are multichannel,
simultaneous sampling, 24-bit, delta-sigma (ΔΣ)
analog-to-digital converters (ADCs) with a built-in
programmable gain amplifier (PGA), internal
reference, and an onboard oscillator.
The ADX92xQ devices incorporate all features
commonly required in portable, low-power
medical electrocardiogram (ECG), sports, and
fitness applications.
With high levels of integration and exceptional
performance, the ADX92xQ devices enable the
creation of scalable medical instrumentation
systems at significantly reduced size, power, and
overall cost.
The ADX92xQ devices have a flexible input
multiplexer per channel that can be
independently connected to the internally-
generated signals for test, temperature, and lead-
off detection. Additionally, any configuration of
input channels can be selected for derivation of
the right leg drive (RLD) output signal. The
ADX92xQ devices operate at data rates up to
8kSPS. Lead-off detection can be implemented
internal to the device, using the device internal
excitation current sink or source. The ADX922Q and
ADX923Q versions include a fully integrated
respiration impedance measurement function.
Operating temperature is specified from –40°C to
125°C.