EVAL-AD7856CB

–2–

REV. 0

LINK AND SWITCH OPTIONS

There are 25 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.

Function.

LK1 - LK8 These links are used to connect input to the op-amps to the relevant AIN socket or to Agnd.

When a link is in position "A" the associated AIN socket is connected to the input buffer.

When a link is in position "B" the input to the analog buffer is connected to Agnd.

LK12

This link option selects the source of the CLKIN input. This link should be removed if the AD7856's inter-

nal clock is selected (see LK8).

When this link is "IN" the CLKIN input is provided by the EVAL-CONTROL BOARD.

When this link is "OUT" the external CLKIN input must be provided via the external socket, J4.

LK13

This link option selects the source of the

CONVST input.

When this link is "IN" the

CONVST input is provided by the EVAL-CONTROL BOARD.

When this link is "OUT" the

CONVST input must be provided via the external socket, J5.

LK15

This link option connects the BUSY output to the EVAL-CONTROL BOARD where it is used as an inter-

rupt request. This link is always "IN" when using the EVAL-CONTROL BOARD.

LK16

This link option is used to put the AD7856 in SLEEP mode or in NORMAL mode.

When a link is in position "A" the AD7856 is put into NORMAL mode.

When a link is in position "B" the AD7856 is put into SLEEP mode.

LK17

This link selects the source of the AVdd/DVdd +5V supply.

When this link is in position "A" the +5V must be supplied from an external source via power connector J2.

When this link is in position "A" the +5V is supplied from the EVAL-CONTROL BOARD.

LK18

This link option adds a 50

Ω termination to Dgnd on the CLKIN line.

This link should "OUT" when using the CLKIN from the EVAL-CONTROL BOARD.

If a 50

Ω termination is required when using an external CLKIN siganl this link should be "IN".

LK19

This link option adds a 50

Ω termination to Dgnd on the CONVST line.

This link should "OUT" when using the

CONVST from the EVAL-CONTROL BOARD.

If a 50

Ω termination is required when using an external CONVST siganl this link should be "IN".

LK20

This link option is used to select the source of the +12V supply

In position A, the +12V is supplied from the EVAL-CONTROL BOARD through the 96 way connector.

In position B, the +12V is supplied from an external source through the power connector, J3.

LK21

This link option is used to select the source of the -12V supply.

In position A, the -12V is supplied from the EVAL-CONTROL BOARD through the 96 way connector.

In position B, the -12V is supplied from an external source through the power connector, J3.

LK23

This link option is used to connect the CREF1 pin to +5V.

If AVdd is used as the reference voltage at the REFIN/OUT pin or an external reference approaching AVdd

is used this link must be "IN" to connect the CREF pin to AVdd.

This link must be "OUT" if using the AD7856 internal reference voltage.

LK24

This link option adds a 50

Ω termination to Agnd on the Vin line.

If a 50

Ω termination is required at the Analog input socket, J7, this link should be "IN".

LK25

This link is used to select the reference voltage for the AD7856.

In position "A", the AD7856 internal 4.096V reference is used.

In position "B",

an external reference voltage may be applied via the VREF socket, J6.

In position "C", AVDD is used as the reference voltage.