ADS1291_14 Datasheet, PDF (50/75 Pages) Texas Instruments – Power, 2-Channel, 24-Bit Analog Front-End for Biopotential Measurements

ADS1291
ADS1292
ADS1292R
SBAS502B – DECEMBER 2011 – REVISED SEPTEMBER 2012
ECG-SPECIFIC FUNCTIONS
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INPUT MULTIPLEXER (REROUTING THE RIGHT LEG DRIVE SIGNAL)
The input multiplexer has ECG-specific functions for the right leg drive signal. The RLD signal is available at the
RLDOUT pin once the appropriate channels are selected for RLD derivation, feedback elements are installed
external to the chip, and the loop is closed. This signal can be fed after filtering or fed directly into the RLDIN pin,
as shown in Figure 47. This RLDIN signal can be multiplexed into any one of the input electrodes by setting the
MUX bits of the appropriate channel set registers to '0110' for P-side or '0111' for N-side. Figure 47 shows the
RLD signal generated from channel 1 and routed to the N-side of channel 2. This feature can be used to
dynamically change the electrode that is used as the reference signal to drive the patient body. Note that the
corresponding channel cannot be used and can be powered down.
IN1P
IN1N
EMI
Filter
MUX1[3:0] = 0000
PGA1
RLD1P = 1
RLD1N = 1
IN2P
IN2N
EMI
Filter
MUX1[3:0] = 0111
MUX
ADS1292R
PGA2
RLD2P = 0
RLD2N = 0
RLDREF_INT = 1
(AVDD + AVSS)
2
RLDREF_INT = 0
RLD_AMP
RLDIN/RLDREF
Filter or
Feedthrough
RLDOUT
1 M ⁽¹⁾
RLDINV
1.5 nF⁽¹⁾
(1) Typical values for example only.
Figure 47. Example RLDOUT Signal Configured to be Routed to IN2N
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