Datasheet

Data Sheet ADAS1000-3/ADAS1000-4
Rev. A | Page 43 of 76
Common Mode
The ADAS1000-3/ADAS1000-4 have a dedicated CM_OUT
pin serving as an output and a CM_IN pin as an input. In
gang mode, the master device determines the common-mode
voltage based on the selected input electrodes. This common-
mode signal (on CM_OUT) can then be used by subsequent
slave devices (applied to CM_IN) as the common-mode
reference. All electrodes within the slave device are then
measured with respect to the CM_IN signal from the master
device. See the CMREFCTL register in Table 31 for more
details on the control via the serial interface. Figure 70 shows
the connections between a master and slave device using
multiple devices.
Right Leg Drive
The right leg drive comes from the master device. If the
internal RLD resistors of the slave device are to contribute
to the RLD loop, tie the RLD_SJ pins of master and slave
together.
Sequencing Devices into Gang Mode
When entering gang mode with multiple devices, both
devices can be configured for operation, but the conver-
sion enable bit (ECGCTL register, Bit 2, Table 27) of the
master device should be set after the conversion enable bit
of the slave device. When the master device conversion
signal is set, the master device generates one edge on its
SYNC_GANG pin. This applies to any slave SYNC_GANG
inputs, allowing the devices to synchronize ADC conversions.