EVAL-AD7891-1CB Datasheet, PDF (2/12 Pages) Analog Devices – Evaluation Board for Single Supply, 12-Bit 454 kSPS ADC

EVAL-AD7891-1CB
Link Options
There are thirty one link options on the evaluation board which must be set for the required operating setup before use. The func-
tions of these options are outlined below.
Link No.
LK1 - LK8
LK9 - LK16
LK17 - LK24
LK25
LK26
LK27
LK28
LK29
LK30
LK31
Function
LK1 to LK8 select the voltages applied to the inputs of the quad op-amp buffers. LK1 selects the voltage for
channel 1, LK2 selects the voltage for channel 2 etc.
In position A, the input is connected to the SMB connector.
In position B, the input is connected to AGND. If no voltage is present at the SMB connector then the link
should be in position B.
LK9 to LK16 are used to select the voltages applied to the V_INXA inputs of the AD7891-1. LK9 selects the voltage
that is applied to V_IN1A, LK10 selects the voltage applied to V_IN2A etc.
In position A the buffered input voltage from AINx is connected to V_INXA.
In position B, V_INXA is connected to AGND.
LK17 to LK24 are used to select the voltage applied to the V_INXB inputs of the AD7891-1. LK17 selects the
voltage that is applied to V_IN1B, LK18 selects the voltage that is applied to V_IN2B etc.
In position A, the buffered reference voltage is applied to V_INXB.
In position B, the buffered input voltage from AINx is connected to V_INXB.
In position C, V_INXB is connected to AGND.
This link option selects the reference source for the AD7891 REF OUT/REF IN pin.
With this link in position A, the reference connects to the SMB socket, SKT9.
In position B, the AD780 +2.5V reference is selected as the reference for the AD7891-1.
With this link out, the REF OUT/REF IN pin remains open-circuited, thus the reference source is the AD7891-1's
internal reference.
This link selects the V_DD source.
In position A, the V_DD supply is taken from the external V_DD connector.
In position B, the V_DD supply is taken from the 96 way connector.
This link selects the +12V source.
In position A, the +12V supply is taken from the external +12 V connector.
In position B, the +12V supply is taken from the 96 way connector.
This link selects the -12 V source.
In position A, the -12 V supply is taken from the external -12 V connector.
In position B, the -12 V supply is taken from the 96 way connector.
This link option selects the voltage applied to the STANDBY pin of the AD7891-1. The voltage applied to the
STANDBY pin can also be controlled from pin 9 of the 9-way D-type socket. If pin 9 of the 9-way D-type socket
is used to control the voltage applied to the STANDBY pin then LK29 should be left unconnected.
In position A, the STANDBY pin is connected to V_DD.
In position B, the STANDBY pin is connected to DGND.
This link option selects the source for the CONVST input of the AD7891-1.
In position A, the CONVST pin is connected to the FL0 pin on the 96-way connector. When using the evaluation
board with the EVAL-CONTROL BOARD, there are two program options, one where the CONVST signal is
generated from the EVAL-CONTROL BOARD; the second where the CONVST signal is externally supplied.
When the internal CONVST program is used, this link must be in position A.
In position B, the signal applied to the SMB connector, SKT10 provides the CONVST signal for the AD7891-1.
This link option selects the voltage applied to the MODE pin of the AD7891-1 and hence selects the interface
mode used for the part.
In position A, the MODE pin is connected to DGND, which selects the serial interface mode.
In position B, the MODE pin is connected to V_DD, which selects the parallel interface mode.
–2–
REV. A