Datasheet

RLD
Amp
(AVDD+AVSS)/2
RLDREF_INT
RLDREF_INT
RLD_REF
RLD_OUT
RLD_INV
RLD
ADS119x
WCT_TO_RLD
FromWCTAmplifiers
RLD_REF
WCT
RLDINVRLD
OUT
RLD
REF
RLDIN
VA1-8
Device2
VA1-8
RLDINVRLD
OUT
RLD
REF
RLDIN
VA1-8
DeviceN
VA1-8
Power-Down Power-Down
RLDINVRLD
OUT
RLD
REF
RLDIN
VA1-8
Device1
VA1-8
ToInputMUX ToInputMUX ToInputMUX
ADS1194, ADS1196
ADS1198
SBAS471C –APRIL 2010– REVISED NOVEMBER 2011 www.ti.com
WCT as RLD
In certain applications, the right leg drive is derived as the average of RA, LA, and LL. This level is the same as
the WCT voltage. The WCT amplifier has limited drive strength and thus should be used only to drive very high
impedances directly. As shown in Figure 51, the ADS1194/6/8 provide an option to internally buffer the WCT
signal by setting the WCT_TO_RLD bit in the CONFIG4 register. The RLD_OUT and RLD_INV pins should be
shorted external to the device. Note that before the RLD_OUT signal is connected to the RLD electrode, an
external amplifier should be used to invert the phase of the signal for negative feedback.
Figure 51. Using the WCT as the Right Leg Drive
RLD Configuration with Multiple Devices
Figure 52 shows multiple devices connected to an RLD.
Figure 52. RLD Connection for Multiple Devices
60 Submit Documentation Feedback Copyright © 2010–2011, Texas Instruments Incorporated
Product Folder Link(s): ADS1194 ADS1196 ADS1198