EVAL-AD7903SDZ Datasheet, PDF (8/32 Pages) Analog Devices – EVAL-AD7903SDZ User Guide UG-609

UG-609
EVALUATION BOARD HARDWARE
DEVICE DESCRIPTION
The AD7903 is a 16-bit, 1 MSPS, precision, power efficient, dual
differential PulSAR ADC that uses SAR-based architecture and
does not exhibit any pipeline delay or latency. The AD7903 is
specified for use with a single supply of 2.5 V (VDD1, VDD2).
The interface from the digital host to the AD7903 uses 1.8 V/
2.5 V/3.3 V/5.5 V logic. The AD7903 is compatible with the
SPI/QSPI/MICROWIRE/DSP serial interface to transfer data
conversions. Complete AD7903 specifications are provided in
the AD7903 data sheet and should be consulted in conjunction
with this user guide when using the evaluation board. Full
details on the EVAL-SDP-CB1Z are available on the Analog
Devices website, at www.analog.com.
Figure 26 to Figure 31 show the evaluation board schematics.
The board consists of an AD7903 ADC (U1) with a reference
(U6—ADR435), and several ADC drivers (U12, U14, U16, and
U17—ADA4841-1YRZ). The evaluation board is a flexible
design that enables you to adjust compensation components
and operate the evaluation board from an adjustable bench top
power supply.
POWER SUPPLIES
The evaluation board can be powered from a wall adapter or
from a bench top power supply. By default, the board is set up
to operate from a 9 V wall adapter using the on-board power
supplies described in Table 1.
Table 1. Power Supplies Provided on the Board
Power Supply (V) Function
Components Used
+5
SDP power
ADP2301
+7.5
Positive rail
ADP7104
−2.5
Negative rail
ADP2301
+2.5
ADC VDD rail
ADP7104
+3.3
VDRIVE (digital power) ADP7104
EVAL-AD7903SDZ User Guide
Each on-board power supply is decoupled where it enters the
board as well as where it connects to each device. A single ground
plane is used on this board to minimize the effect of high frequency
noise interference.
Alternatively, the board can be powered from a bench top power
supply by using the J2 and J3 screw terminals and changing the
SL1 to SL4 and LK3 to LK5 solder link settings to Position B (see
Table 2). When bench top power is used, use of the wall adapter
and the on-board power supplies are no longer required.
Table 2. Solder Links—Settings for Bench Top Power Supply¹
Link
Setting
Function
SL1
B
+VS
SL2
B
−VS
SL3
B
−VS
SL4
B
+VS
LK3
B
V_SDP
LK4
B
VREF
LK5
B
VDD for ADC
1 _{All other solder link settings are as described in Table 3.}
Rev. 0 | Page 8 of 32