Datasheet
DOUT MODES
TDM Mode
CH1
DOUT1
( )ADS1174
SCLK
DRDY
(SPI)
FSYNC
(Frame-Sync)
1 2
16 1715 32 3331
48
4947 64 6563 6766
CH1
DOUT1
( )ADS1178
113
CH2
CH2
CH3
CH3
CH4
CH4
DIN
CH5
127
CH8 DIN
128 129 130 131
CH1
DOUT1
( )ADS1174
CH2 CH3 DINCH4
SCLK
DRDY
(SPI)
FSYNC
(Frame-Sync)
1 2
16 1715 32 3331 48 4947 64
65
63 66
67
CH1
DOUT1
( )ADS1178
CH2 CH3 CH5CH4
113
CH8 DIN
127 128
129
130 131
ADS1174
ADS1178
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........................................................................................................................................ SBAS373B – OCTOBER 2007 – REVISED SEPTEMBER 2008
output from another ADS1174, ADS1178, or other
compatible device. Note that when all channels of the
For both SPI and Frame-Sync interface protocols,
ADS1174/78 are powered down, the interface is
either the data are shifted out through individual
powered down, rendering the DIN input powered
channel DOUT pins in a parallel data format (Discrete
down as well. When one or more channels of the
mode), or the data for all channels are shifted out in
device are powered down, the data format of the
series through common pin DOUT1 (TDM mode).
TDM mode can be fixed or dynamic.
TDM Mode, Fixed-Position Data
In time division multiplexed (TDM) data output mode,
In this TDM data output mode, the data position of
the data for all channels are shifted out, in series, on
the channels remains fixed, regardless of whether
a single pin (DOUT1). As shown in Figure 17 , the
channels are disabled. If a channel is powered down,
data from channel 1 are shifted out first, followed by
data are forced to zero, but occupy the same position
channel 2 data, etc. After the data from the last
within the data stream. Figure 18 shows the data
channel are shifted out (channel 4 for the ADS1174
stream with channel 1 and channel 3 powered down.
or channel 8 for the ADS1178), the data from the DIN
input follow. DIN is used to daisy-chain the data
Figure 17. TDM Mode (All Channels Enabled)
Figure 18. TDM Mode, Fixed-Position Data (Channels 1 and 3 Shown Powered Down)
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