ADS8528_14 Datasheet, PDF (34/52 Pages) Texas Instruments – 12-, 14-, 16-Bit, Eight-Channel, Simultaneous Sampling ANALOG-TO-DIGITAL CONVERTERS

ADS8528
ADS8548
ADS8568
SBAS543A – AUGUST 2011 – REVISED OCTOBER 2011
www.ti.com
Daisy-Chain Mode
The serial interface of the ADS8528/48/68 supports a daisy-chain feature that allows cascading of multiple
devices to minimize the board space requirements and simplify routing of the data and control lines. In this case,
pins DB3/DCIN_A, DB2/DCIN_B, DB1/DCIN_C, and DB0/DCIN_D are used as serial data inputs for channels A,
B, C, and D, respectively. Figure 40 shows an example of a daisy-chain connection of three devices sharing a
common CONVST line to allow simultaneous sampling of 24 analog channels along with the corresponding
timing diagram.
To activate the daisy-chain mode, the DCEN pin must be pulled high. However, the DCEN of the first device in
the chain must remain low.
In applications in which not all channel pairs are used, it is recommended to declare the part with disabled
channel pair(s) to be the first in the daisy-chain.
CONVST
FS
SCLK
ADS85x8
#1
CONVST_A/B/C/D
FS
SCLK
SDO_A
SDO_B
SDO_C
SDO_D
DCEN
DGND
ADS85x8
#2
DVDD
CONVST_A/B/C/D
FS
SCLK
DCIN_A ^SDO_A
DCIN_B SDO_B
DCIN_C SDO_C
DCIN_D _{SDO_D}
DCEN
ADS85x8
#3
DVDD
CONVST_A/B/C/D
FS
SCLK
DCIN_A ^SDO_A
DCIN_B SDO_B
DCIN_C SDO_C
DCIN_D _{SDO_D}
DCEN
To
Processing
Unit
CONVST
BUSY
(C27 = C26 = 0)
FS
SDO_x #3
Don’t Care
16-Bit Data CHx0
ADS85x8 #3
16-Bit Data CHx1
ADS85x8 #3
16-Bit Data CHx0
ADS85x8 #2
16-Bit Data CHx1
ADS85x8 #2
16-Bit Data CHx0
ADS85x8 #1
16-Bit Data CHx1
ADS85x8 #1
Figure 40. Example of Daisy-Chaining Three Devices
34
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Product Folder Link(s): ADS8528 ADS8548 ADS8568