EVAL-AD7476 Datasheet, PDF (2/12 Pages) Analog Devices – Evaluation Board for 1MSPS, 12-/ 10-Bit ADCs

EVAL-AD7476/77CB
LINK AND SWITCH OPTIONS
There are 12 link options which must be set for the required operating setup before using the evaluation board. The
functions of these options are outlined below.
Link No.
LK1
LK2
LK3
LK4
LK5
LK6
LK7
LK8-9
LK10
LK11
LK12
Function.
This link option is used to select a 50W termination on the analog input buffer circuit.
When this link is “inserted” the 50W termination is applied.
When this link is “removed” the 50W termination is removed.
This link option controls the program pin of the AD780 voltage reference.
When this link is “inserted” the AD780 output voltage is set to +3.0 V.
When this link is “removed” the AD780 output voltage is set to +2.5 V.
This link is used to select a 50W termination on the input of the bias-up circuit.
When this link is “inserted” the 50W termination is applied.
When this link is “removed” the 50W termination is removed.
This link option is used to connect the output of either the REF195 or the AD780 to the V_DD
AD7476/77 ( if link 12 is in position C).
When this link is in position A the AD780 supplies the V_DD voltage for the AD7476/77.
When this link is in position B the REF195 supplies the V_DD voltage for the AD7476/77.
pin of the
This link option sets the DC bias voltage that is applied to the optional bias-up/filter circuit.
When this link is in position “A”, the bias voltage is set to the same level as the voltage that is applied
to the AD7476/77 V_DD pin. In this configuration a bipolar analog input applied to the Vin SMB socket is
biased up by the bias circuit and is presented at the Vbiased SMB as a uni-polar signal biased around
V_DD/2.
When this link option is placed in position “B”, the bias voltage is set to A_GND. In this configuration the bias-
up circuit is not used.
This link option is used to select the source of the +12 V supply.
In position A, the +12 V is supplied from the EVAL-CONTROL BOARD through the 96 way connector.
In position B, the +12 V is supplied from an external source through the power connector, J6.
This link option is used to select the source of the -12 V supply.
In position A, the -12 V is supplied from the EVAL-CONTROL BOARD through the 96 way connector.
In position B, the -12 V is supplied from an external source through the power connector, J6.
These links control the transfer of data from the AD7476/77 during a conversion for various frequencies of
SCLK.
Link 8 and 9 should be in position "A" for slower SCLK frequencies, giving valid data on the rising edge.
Link 8 and 9 should be in position "B" for fast SCLK frequencies, giving valid data on the following edge.
This link selects the source of the Vcc +5 V supply for the 74LS04.
When this link is in position "A", Vcc power is supplied from the same power source supplying the AD7476/
77 V_DD pin.
When this link is in position "B", V_CC power must be must be supplied from an external source via the power
connector, J5.
This link option is used to connect the input of the VIN analog buffer to the AIN input socket or to A_GND.
When this link is in position “A” the AIN socket is tied to the input of the VIN buffer. In this configuration,
an analog signal applied to the Ain input socket is buffered and presented at the AD7476/77 VIN input.
When this link is in position “B” the VIN buffer input is tied to A_GND.
This link selects the source of the V_DD supplied to the AD7476/77.
When this link is in position “A” the V_DD must be supplied from an external source via J5.
When this link is in position “B” the V_DD is supplied from the EVAL-CONTROL BOARD.
When this link is in position “C” the V_DD is supplied from either the AD780 or the REF195 references.
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