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MAXREFDES106# Health Sensor Platform 4.0
Available Options
Table 10. ECG RLD Configuration Options
Enables/Disables Right Leg Drive.
RLD (Driven Body
Bias) Feedback
Selects the RLD operating mode.
DC Buffer Mode = The feedback network is shorted and the RLD
amplifier acts as a DC buffer to bias the body to a voltage
selected by the ‘Body Bias DAC’ option.
Closed-Loop Right Leg Drive Mode = The RLD amplifier applies
the inverting gain to the AC common mode input signal, forming a
feedback loop through the body to bring the ECGP and ECGN
inputs to the voltage selected by the ‘Body Bias DAC’ option.
Common-Mode
Voltage Source
Select
Selects the common-mode inputs to the RLD circuit from either
the filtered CAPP/CAPN pins or directly from the ECGP/ECGN
pins. In general, the ECGP/ECGN pins are better at attenuating
higher frequency common-mode signals such as power-line
interference.
Selects which ECG inputs are averaged and used as an input to
the RLD amplifier. For proper operation, both IN+ and IN- should
be selected.
Configures the body bias voltage to use as input to the RLD
circuit. This is V
MID_ECG
plus or minus a configurable offset. This
offset is used to compensate for electrode offset voltages.
Sets the bandwidth of the inverting common-mode voltage
amplifier. Higher bandwidth consumes more power, and the
lowest bandwidth setting is adequate for power line frequencies.
Sets the gain factor of the inverting common-mode voltage
amplifier. Higher gain settings provide the best common-mode
noise rejection for electrodes with high-contact impedance,
including dry electrodes.
Out of Range
Detect Enabled
Toggles whether the RLD out-of-range detector is enabled. This
detects when the total impedance between the RLD electrode and
input ECG electrodes is too high to maintain the feedback loop,
usually because electrodes are off or have poor contact with the
user.
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