- 2 -

Rev. A

EVAL-AD9835EB

LINK AND SWITCH OPTIONS

There are four link options which must be set for the required operating setup before using the evaluation board.

The

functions of these link options are outlined below.

Link No.

Function

LK1

When SELSRC = 0, the PSEL1 input can be controlled by the user via a SMB connector or alternatively,

by switch SW1-2.

With LK1 in position "A", PSEL1 can be controlled from an external logic source through the SMB

connector, PSEL1.

With LK1 in position"B" PSEL1 is connected to SW1, allowing the user to control the PSEL1signal

using the double throw switch, SW1-2.

LK2

When SELSRC = 0, the PSEL0 input can be controlled by the user via a SMB connector or

alternatively, by switch SW1-1.

With LK2 in position "A", PSEL0 can be controlled from an external logic source through the SMB

connector, PSEL0.

With LK2 in position"B" PSEL0 is connected to SW1, allowing the user to control the PSELOsignal

using the double throw switch, SW1-1.

LK3

When SELSRC = 0, the FSELECT input can be controlled by the user via a SMB connector or alternatively,

by switch SW1-3.

With LK3 in position "A", FSELECT can be controlled from an external logic source through the SMB

connector, FSEL1.

With LK3 in position"B" FSELECT is connected to SW1, allowing the user to control the FSELECT signal

using the double throw switch, SW1-3.

LK4

The reference to the AD9835 can be provided by the on-board reference, which is available at REFOUT,

or an external reference of nominal value 1.21 V can be used. When LK4 is closed, the on-board reference

is used. When this link is opened, REFIN is disconnected from REFOUT and the reference must be provided

by the user via the SMB connector, REFIN1.

SET-UP CONDITIONS

Care should be taken before applying power and signals to the evaluation board to ensure that all link positions are as per the

required operating mode.

Table 1 shows the position in which all the links are set when the evaluation board is packaged.

Table 1:

Initial Link and Switch Positions

Link No.

Position

Function

LK1

B

LK1 is arranged so that PSEL1 is tied to SW1-2.

LK2

B

LK2 is arranged so that PSEL0 is tied to SW1-1.

LK3

B

LK3 is arranged so that FSELECT is tied to SW1-3.

LK4

I N

REFOUT is tied to REFIN.

SW1