Analog Devices EVAL-AD7715-5EB Instructions Manual page 2

EVAL-AD7715-5EB
Link Options
There are a number of link options on the evaluation board which should be set for the required operating setup before using the
board. The functions of these link options are described in detail below.
Link No. Function
LK1 This option selects the master clock option for the AD7715. The master clock source comes from the on-board
crystal or from an external clock source via SKT7. This is a double link and both links must be moved together for
correct operation.
With both links in position A, the external clock option is selected and an externally applied clock to SKT 7 is routed
the MCLK IN pin of the AD7715.
With both links in position B, the on-board crystal is selected and provides the master clock for the AD7715.
LK2 This link option is used to select the reference source for the AD7715's REF IN(-) input.
With this link in position A, the REF IN(-) pin of the AD7715 is connected directly to AGND.
With this link in position B, the REF IN(-) pin of the AD7715 is connected to SKT5. An external voltage connected
to SKT5 can now be used for REF IN(-).
LK3 This link option is used to select the reference source for the AD7715's REF IN(+) input.
With this link in position A, the REF IN (+) pin of the AD7715 is connected directly to the output of the on-board
reference, the AD780.
With this link in position B, the REF IN(+) pin of the AD7715 is connected to SKT6. An external voltage connected
to SKT 6 can now be used for REF IN(+).
LK4 This link option is set depending on the type of reference being used on the evaluation board. Although the board is
equipped with an AD780, a REF-192 +2.5V reference can replace it in the same socket. When a REF-192 reference
is used on the board, the link should be in either position A or position B. In position A, the REF-192's shutdown pin
is connected to DV
is connected to DGND, placing the REF-192 in power down mode.
When the AD780 reference is used, the link should be in position C as the AD780 does not have a shutdown pin.
LK5 This link is in series with the AIN (+) analog input.
With this link in place, the analog input on the SKT3 input is connected directly to the AIN(+) input on the part.
This link may be removed so that the input signal at SKT3 can be connected to the component grid for signal
conditioning before being applied to the AIN(+) input of the AD7715.
LK6 This link is in series with the AIN (-) analog input.
With this link in place, the analog input on the SKT4 input is connected directly to the AIN(-) input on the part.
This link may be removed so that the input signal at SKT4 can be connected to the component grid for signal
conditioning before being applied to the AIN(-) input of the AD7715.
, placing the REF-192 in normal mode of operation. In position B, the REF-192's shutdown pin
DD
–2– REV. A