Datasheet
CONVST
SDO
SCLK
SDI
CONVST
SDO
SCLK
SDI SDI
CLK
CNV
ADS8319#2
DigitalHost
IRQ
ADS8319#1
1 2
15
16
CONVST
ACQUISITION
CONVERSION
ACQUISITION
SCLK
SDO #2
t
7
t
2
t
3
t
clkh
t
clkl
t
clk
17
18
31
32
#1-D15 #1-D14 #1-D1
#1-D0
#2-D15
#2-D14
#2-D1
#2-D0
SDO #1, SDI #2
#1-D15 #1-D14 #1-D1
#1-D0
t
8
t
cnv
t
cyc
t
acq
t
6
ADS8319
SLAS600A –MAY 2008–REVISED SEPTEMBER 2013
www.ti.com
Refer to Figure 53 for the connection diagram. SDI for device 1 is tied to ground and SDO of device 1 goes to
SDI of device 2 and so on. SDO of the last device in the chain goes to the digital host. CONVST for all of the
devices in the chain are tied together. In this mode there is no CS signal. The device SDO is driven low when
SDI low selects daisy chain mode and the device samples the analog input and enters the conversion phase. It is
necessary that SCLK is low at the rising edge of CONVST so that the device does not generate a busy indicator
at the end of the conversion. In this mode CONVST continues to be high from the start of the conversion until all
of the data bits are read. Once started, conversion continues irrespective of the state of SCLK.
At the end of the conversion, every device in the chain initiates output of its conversion data starting with the
MSB bit. Further the next lower data bit is output on every falling edge of SCLK. While every device outputs its
data on the SDO pin, it also receives previous device data on the SDI pin (other than device #1) and stores it in
the shift register. The device latches incoming data on every falling edge of SCLK. SDO of the first device in the
chain goes low after the 16th falling edge of SCLK. All subsequent devices in the chain output the stored data
from the previous device in MSB first format immediately following their own data word.
It needs 16 × N clocks to read data for N devices in the chain.
Figure 54. Interface Timing Diagram, Daisy Chain Mode Without Busy Indicator
Daisy Chain Mode With Busy Indicator
Figure 55. Connection Diagram, Daisy Chain Mode With Busy Indicator (SDI = 0)
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