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MAXREFDES106# Health Sensor Platform 4.0
Respiration Mode
(Balanced
Source/Sink)
Enabling Respiration Mode allows for balanced square wave
source/sink current stimulation, and the Current DAC Drive
Mode is ignored.
Respiration
Mode
Configuration
(Balanced
Source/Sink)
Drive Current/ 4x
Current
Set the magnitude of square wave current. For safety reasons,
4x current should not be asserted unless the stimulus frequency
is greater than 10kHz.
Chop Clock
Divider/Mode/Low-
Pass Filter
Sets the settings for chopping BioZ measurement. Enabling
chopping and CMFB with LPF reduces 1/f and 50Hz/60Hz
noise. Refer to the MAX86178 data sheet ‘BioZ Transmit
Channel’ section for details.
Enable Drive Out of
Range (OOR)
Detection
The sine-wave current drive has a maximum DRVN output
compliance voltage of 0.2 to (V
DD
– 0.2) volts. If ‘Drive OOR’ is
selected, the DRVN OOR flag is asserted if the output voltage
exceeds a range of 0.27 to (V
DD
– 0.32) volts. The DRVN OOR
indicator is located on the ‘Plots’ tab when the ‘Respiration
(BioZ)’ plot is selected.
BioZ Receive Tab
This tab comprises an input MUX, a by-passable and programmable analog high-pass filter, an
instrumentation amplifier with programmable gain, demodulator, anti-alias filter, another programmable
gain amplifier, and an analog-to-digital converter (ADC). Refer to the MAX86178 data sheet for more
details. See the available options in Table 12 for more details.
Figure 61. BioZ Receive Tab
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