EVAL-AD7484_15 Datasheet, PDF (3/20 Pages) Analog Devices – Evaluation Board for 3 MSPS, 14-Bit SAR ADC

EVAL-AD7484
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:
• AVDD
• AGND
• +12 V
• −12 V
• AGND
• DVDD
• DGND
• VDRIVE
• DGND
If the evaluation board is used in standalone mode, a +5 V
supply must be connected to both the AVDD and DVDD inputs.
The +12 V and −12 V supplies are required for the op amps.
The VDRIVE input can be connected to a supply from +2.7 V to
+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
ceramic capacitors, as are the VDD pins of the AD7484.
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 B, connects the bias up voltage to AVDD.
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 A, connects the STBY (standby) pin to DVDD, putting the part 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 A, connects the NAP pin to DVDD, putting the part 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 A, ties the CLIP pin to DVDD.
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 A, ties the MODE1 pin to DVDD.
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 A, ties the MODE2 pin to DVDD.
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.
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