Datasheet

EVAL-AD7400/AD7401
Rev. 0 | Page 3 of 12
EVALUATION BOARD HARDWARE
POWER SUPPLIES
When using this evaluation board with the EVAL-CED1Z, the
V
DD1
and V
DD2
supplies (that is, the isolated and nonisolated
supplies) must be supplied by an external source via the J1
and J4 connectors respectively. The isolated supply, V
DD1
, can
be supplied with a voltage from 4.5 V to 5.25 V while V
DD2
must
be supplied with a 3.3 V supply when used in conjunction with
the EVAL-CED1Z. This is because the EVAL-CED1Z operates
with a 3.3 V logic level. When using the board as a standalone
unit, external supplies must be provided for V
DD1
, V
DD2
, and the
op amp supplies. This evaluation board has the following power
supply inputs: V
DD1
(+5 V), V
DD2
(+3V to +5 V), (−5 V), GND
1
.
and GND
2
. The (−5 V) supply is only required if the external
AD797 op amps are used to buffer the analog inputs to the
AD7400 and AD7401.
The supplies are decoupled to the relevant ground plane with
10 μF tantalum and 0.1 μF multilayer ceramic capacitors at the
point where they enter the board.
The AD7400 and AD7401 evaluation board has split ground
planes, that is, both the isolated and nonisolated side of the
device have completely separate ground plans to preserve the
isolation. The board is split beneath the AD7401 and AD7400
package so that signals on one side of the AD7400 and AD7401
are completely isolated from signals on the other side.
LINK OPTIONS
There are seven link options and two solder links that must be
set correctly to select the appropriate operating setup before
using the evaluation board. The functions of the options are
outlined in Table 1.
Table 1. Link Option Functions
Link No. Function
J7
This link selects the destination for the MCLKOUT output on the AD7400 and the source of the MCLKIN input on
the AD7401.
In Position A, the MCLKOUT signal on the AD7400 goes to the SPORT connector on the EVAL-CED1Z board. The
MCLKIN signal on the AD7401 is supplied via the SPORT connector by the EVAL-CED1Z board.
In Position B, the MCLKOUT signal on the AD7400 goes to the J5 SMB socket. The MCLKIN input on the AD7401
must be supplied by an external source via the J5 SMB socket.
J8 This link option selects the destination of the MDAT output signal from the AD7400 or AD7401.
In Position A, the MDAT signal goes to the SPORT connector on the EVAL-CED1Z board.
In Position B, the MDAT signal goes to the J6 SMB socket.
J9 This link option selects the source of the V
DD2
supply, the nonisolated supply, for the AD7400 or AD7401.
In Position A, V
DD2
must be supplied from an external source via the J4-1 connector.
In Position B, the V
DD2
input on the AD7400 or AD7401 is connected to the 5 V supply from the EVAL-CED1Z.
In Position C, the V
DD2
input on the AD7400 or AD7401 is connected to the 2.5 V supply from the EVAL-CED1Z.
J10 This link option selects the source of the V
IN
+ analog input to the AD7400 or AD7401.
In Position A, the V
IN
+ analog input to the AD7400 or AD7401 is buffered by the AD797 (U2). This link option should
be used in conjunction with J11, which should be placed in Position A.
In Position B, the V
IN
+ analog input to the AD7400 or AD7401 is not buffered by the AD797 (U2). This link option
should be used in conjunction with J11, which should be placed in Position B.
In Position C, the V
IN
+ analog input to the AD7400 or AD7401 is tied directly to GND
1
.
J11 This link selects if the analog input to the J2 SMB, is buffered by the AD797 (U2).
In Position A, the analog input signal supplied to the J2 SMB is fed directly to the AD797 for buffering. This link
option should be used in conjunction with J10, which should be placed in Position A.
In Position B, the analog input signal supplied to the J2 SMB is fed directly to the V
IN
+ input of the AD7400 or
AD7401; therefore, it is not buffered. This link option should be used in conjunction with J10, which should be
placed in Position B.
J13 This link selects if the analog input to the J3 SMB, is buffered by the AD797 (U3).
In Position A, the analog input signal supplied to the J3 SMB is fed directly to the AD797 (U3) for buffering. This link
option should be used in conjunction with J14, which should be placed in Position A.
In Position B, the analog input signal supplied to the J3 SMB is fed directly to the V
IN
+ input of the AD7400 and
AD7401; therefore, it is not buffered. This link option should be used in conjunction with J14, which should be
placed in Position B.