EVAL-AD7484

Rev. 0 | Page 3 of 20

EVALUATION BOARD HARDWARE

POWER SUPPLIES

When using this evaluation board with the EVAL-CONTROL

BRD2, all supplies are provided from the EVAL-CONTROL

BRD2 through the 96-way connector. When using the board as

a standalone unit, external supplies must be provided.

This evaluation board has nine power supply inputs:

•

•

AGND

•

+12 V

•

−12 V

•

AGND

•

•

DGND

•

•

DGND

If the evaluation board is used in standalone mode, a +5 V

The +12 V and −12 V supplies are required for the op amps.

+5 V, allowing the evaluation board to be connected to both

+3 V and +5 V systems. The supplies are decoupled to the

ground plane with 10 μF tantalum and 0.1 μF multilayer cera-

mic capacitors at the point where they enter the board. Noise on

the supplies is further reduced with the use of EMC filters and

ferrite beads. The supply pins of all the op amps and the

reference are also decoupled with 10 μF tantalum and 0.1 μF

This evaluation board consists of four layers. One of these layers

is used as a dedicated ground plane, which allows for good

decoupling and shielding.

LINK OPTIONS

There are 25 link options that must be set according to

operating setup requirements before the evaluation board can

be used. These link options and their functions are listed in

Table 1. There is no Link 25.

Table 1. Link Options and Functions

Link No.

Function

LK1

Selects the source of CONVST input.

In Position A, sources CONVST from the external connector, J9.

In Position B, connects CONVST to the 96-way connector.

LK2

Selects the source for the bias up voltage.

In Position A, connects the bias up voltage to the reference voltage (divided down by R6 and R8).

In Position C, connects the bias up voltage to the external connector, J10.

LK3

Shorts out the 1 kΩ series input resistor on the analog input.

LK4

In conjunction with LK5, selects the op amp to use in the analog input bias up circuitry. Both links must be set to the same

position.

In Position A, selects the AD829.

In Position B, selects the AD8022.

LK5

See LK4.

LK6

Puts the AD7484 in standby mode.

In Position B, connects the STBY (standby) pin to GND for normal operation.

LK7

Puts the AD7484 in nap mode.

In Position B, connects the NAP pin to GND for normal operation.

LK8

Selects whether the clip input is tied high or low. See the AD7484 data sheet for additional details.

In Position B, ties the CLIP pin to GND.

LK9

Selects whether the MODE1 input is tied high or low. See the AD7484 data sheet for additional details.

In Position B, ties the MODE1 pin to GND.

LK10

Selects whether the MODE2 input is tied high or low. See the AD7484 data sheet for additional details.

In Position B, ties the MODE2 pin to GND.

LK11

Configures the AD7484 for use with an internal or external reference. With this link in position, the part is configured for use with

an external +2.5 V reference.