ADS8413 Datasheet, PDF (15/38 Pages) Burr-Brown (TI) – 16-BIT, 2-MSPS, LVDS SERIAL INTERFACE, SAR ANALOG-TO-DIGITAL CONVERTER

ADS8413
www.ti.com
SLAS490 – OCTOBER 2005
MULTIPLE DEVICES IN DAISY CHAIN OR CASCADE
Multiple devices can be connected in either a daisy chain or cascade configuration. The following sections
describes detailed timing diagrams and electrical connections. The ADS8413 provides all of the hand-shake
signals required for both of these modes. CONVST or CSTART is the only external signal needed for operation.
DAISY CHAIN
Figure 10 shows the first two devices in daisy chain. The signals shown by double lines are LVDS and the others
are CMOS. Daisy chain mode is selected by setting MODE_C/D = 0. The first device in the chain is identified by
selecting LAT_Y/N = 0.
See Table 1
External Clock
(Optional)
See Table 1
Device 1
SDI
SD0
CLK_I
SYNC_I
CLK_0
SYNC_0
Device 2
SDI
SD0
CLK_I
SYNC_I
CLK_0
SYNC_0
To Next Device
or Receiver
Last_Device
BUS_BUSY
RD
BUS_BUSY
+V
CLK_I/E
MODE_C/D LAT_Y/N
CS
RD
BUS_BUSY
+V
CLK_I/E
LAT_Y/N
MODE_C/D
CS
From Controller
Figure 10. Connecting Multiple Devices in Daisy Chain
For all of the other devices in the chain LAT_Y/N = 1. See Table 1 for more details on device configurations.
SDO, CLK_O, and SYNC_O of device n are to be connected to SDI, CLK_I, and SYNC_I of the n+1 device.
SDO, CLK_O, and SYNC_O of the last device in the chain go to the receiver. BUS_BUSY of device n is
connected to RD of device n+1 and so on. Finally, BUS_BUSY of the last device in the chain is connected to RD
of device 1. This ensures the necessary handshake to seamlessly propagate the data of all devices through the
chain (it is also allowed to tie RD = 0 for device 1).
TIMING DIAGRAMS FOR DAISY CHAIN OPERATION
The conversion speed for n devices in the chain must be selected such that:
1/conversion speed > read startup delay + n*(data frame duration) + t_d16
Read startup delay = 10 ns + (t_d19 - t_d4) + t_d12 + 2/f_CLK
Data frame duration = 16/f_CLK
Note that it is not necessary for all devices in the chain to sample the data simultaneously. But all of the devices
must operate with the same exact conversion speed.
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