Datasheet

MUX1[2:0] = 000
RLD_SENSP[0] = 1
RLD_SENSN[0] = 1
MUX2[2:0] = 000
MUX3[2:0] = 000
MUX8[2:0] = 111
PGA1
RLD_SENSP[1] = 1
RLD_SENSN[1] = 1
PGA2
RLD_SENSP[2] = 1
RLD_SENSN[2] = 1
PGA3
RLD_AMP
RLD_SENSP[7] = 0
RLD_SENSN[7] = 0
PGA8
RLDOUT RLDINVRLDREFRLDIN
Filter or
Feedthrough
ADS1298
¼ ¼
MUX
EMI
Filter
EMI
Filter
EMI
Filter
EMI
Filter
IN1P
¼
IN1N
IN2P
IN3P
IN8P
IN2N
IN3N
IN8N
1MW
(1)
1.5nF
(1)
RLDREF_INT
(AVDD + AVSS)/2
RLDREF_INT
ADS1294, ADS1294R
ADS1296, ADS1296R
ADS1298, ADS1298R
www.ti.com SBAS459I –JANUARY 2010–REVISED JANUARY 2012
ECG-SPECIFIC FUNCTIONS
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 the 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 51. 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 110 for P-side or 111 for N-side. Figure 51 shows the RLD
signal generated from channels 1, 2, and 3 and routed to the N-side of channel 8. 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.
(1) Typical values for example only.
Figure 51. Example of RLDOUT Signal Configured to be Routed to IN8N
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