Datasheet

EVAL-AD5420
Rev. 0 | Page 3 of 12
EVALUATION BOARD HARDWARE
POWER SUPPLIES
The following external supplies must be provided:
• 5 V between the 5 V and 0 V inputs for the digital supply
of the AD5420 and digital circuitry. Alternatively, place
Link 6 in Position A to power the digital circuitry from the
USB port (default).
• 10.8 V to 40 V between the AV
DD
and GND inputs for the
analog supply of the AD5420.
• 10.8 V to 16.5 V between the V+ and AGND inputs for the
analog supply of the AD7321 (on-board ADC) and
ADR435 (on-board voltage reference). If the analog supply
connected to the AV
DD
input is less than 16.5 V, the AD7321
and ADR435 can be powered from this by placing Link 9
in Position A, and the V+ input can be left unconnected.
The analog and digital planes are connected at one location, close
to the AD5420. It is recommended not to connect AGND and
DGND elsewhere in the system to avoid ground loop problems.
Each supply is decoupled to the relevant ground plane with 10 μF
and 0.1 μF capacitors. Each device supply pin is again decoupled
with a 10 μF and 0.1 μF capacitor pair to the relevant ground plane.
Excessive Power Supply
Note that, if a power supply in excess of 16.5 V is to be
connected to the AV
DD
input, LK9 must be in Position B to
prevent potential damage to the 5 V voltage reference and to the
ADC (see U2 and U6, respectively, in Figure 5).
LINK OPTIONS
The position of Link 7 configures the board for either PC
control via the USB port (default setup) or for control by an
external source via J8. The link options on the evaluation board
should be set for the required operating setup before using the
board. The functions of the link options are described in Table 4.
Default Link Option Setup
The default setup is for control by the PC via the USB port. The
default link options are listed in Table 1.
Table 1. Link and Switch Options for PC Control
Link No. Option
LK1 Not applicable
LK2 A
LK3 Inserted
LK4 Not applicable
LK5 B
LK6 A
LK7 A
LK8 A
LK9 A
LK10 Inserted
LK11 Not applicable
LK12 Not applicable
LK13 Inserted
LK14 Not applicable
LK15 C
LK16 Not applicable
LK17 Inserted
LK18 Inserted
Connector J8
1
Pin Descriptions
Table 2. Connector J8 Pin Configuration
2 4 6 8 10
1 3 5 7 9
1
LK7 must be in Position B to enable the use of J8.
Table 3. Connector J8 Pin Descriptions
Pin No. Description
1 SDO
2 Not applicable
3 Digital ground
4 Clear
5 Digital ground
6 Fault
7 SDIN
8 Digital ground
9 SCLK
10 Latch