Preliminary Technical Data

EVAL-AD5933EB

Rev. PrC | Page 5 of 32

Link No.

Function

LK11

The on-board voltage reference ADR423 (U4) can be supplied with an external supply voltage at Terminal Block J6-1.

Alternatively, the input voltage can be supplied to the reference by the 5 V available through the USB connector (J1). By

inserting LK11, LK5, LK4, and LK10, the AD5933 is completely powered from the USB supply; however, it is recommended to

power the three supply pins of the part from an external precision voltage source for best results.

LK12

This link is used to connect the high performance 16 MHz crystal oscillator (Y2) to Pin 8 (MCLK) of the AD5933.

•

When Link 12 (LK12) is inserted and Link 3 (LK3) is removed, the on-board crystal oscillator is connected to the MCLK pin.

•

When Link 12 (LK12) is removed, Link 3 (LK3) should be inserted and an external clock should be applied to the CLK1 SMB

connector.

SMB JUMPER FUNCTIONS

Table 3. SMB Jumper Function Descriptions

SMB

Function

CLK 1

The user can apply an external clock signal to Pin 8 (MCLK) of the AD5933, use the supplied external 16 MHz crystal

oscillator (Y2), or use the internal 16.776 MHz oscillator to clock the AD5933 system.

When Link 3 is inserted and Link 12 is removed, the external clock signal applied at the CLK1 SMB connector is connected to

Pin 8 (MCLK). Alternatively, if Link 3 is removed and Link 12 is inserted, the on-board high performance 16 MHz surface-

mount crystal can be used to clock the system. If the internal 16.776 MHz oscillator is used, the clock signal applied at MCLK

is isolated by an internal multiplexer.

CLK 2

This link is for test purposes only.

VOUT

SMB connector. The signal present at this connector can either be the excitation voltage output from Pin 6 of the AD5933 or

an amplified version, depending on the status of LK1, LK2, and LK6, assuming the presence of a user-supplied external op amp

at U1 (see Figure 1).

VIN

between the VIN and VOUT SMB connectors, and provides a path back to the input pin (VIN, Pin 5). Link 7 must be inserted

for the path to be complete. The external feedback resistor (RFB) has one point connected to this signal path, as shown in

the board schematic (see the Evaluation Board Schematic section) and Figure 2.

LINK SETUP CONDITIONS

Table 4. Default Link Positions (Refer to Figure 2 )

Link

Position

Function

LK1,

LK2

Removed

External Amplifier U1 (optional) connected to VOUT is disconnected. AD5933 VOUT is directly connected to the SMB

connector VOUT.

LK3

Removed

Used in conjunction with Link 12 (LK12). Optional user-supplied clock signal at CLK1 is not connected to Pin 8 (MCLK).

LK4

Inserted

AVDD1 is supplied from the ADR423 reference output.

LK5

Inserted

AVDD2 is supplied from the ADR423 reference output.

LK6

Inserted

Connects the output pin of the AD5933, VOUT, to the VOUT SMB connector.

LK7

Inserted

Connects the input pin of the AD5933, VIN, to the VIN SMB connector.

LK8,

LK9

Inserted

Connects a 15 pF capacitor across the input and output pins of the AD5933. These links are for board manufacturing

the SMB connectors, VOUT and VIN.

LK10

Inserted

DVDD is supplied from the ADR423 reference output.

LK11

Inserted

Connects the 5.0 V supplied from the USB hub of the user PC to the supply input (VDD, Pin 2 of U4) of the on-board

ADR423 reference.

LK12

Inserted

Connects the output of the on-board 16 MHz oscillator to Pin 8 (MCLK) of the AD5933.