AD8556-EVALZ/AD8556CP-EBZ User Guide
UG-896
Rev. A | Page 3 of 9
HARDWARE DESCRIPTION
evaluation boards are
designed for maximum configuration flexibility. An ac signal
can be applied to +V
IN
ac, and the output can be monitored
from V
OUT
ac. DC signals can be differentially applied between
+V
IN
dc and −V
IN
dc, and the results can be monitored using a
voltmeter at V
OUT
. Users can view the filter output signal at the
FILT/DIGOUT pin. The board also allows swapping of the
polarity of the inputs using the V
NEG
P1 and V
POS
P1 switches.
Four resistors (R1A, R1B, R2A, and R2B) simulate a 100 Ω
bridge configuration. The bridge can be unbalanced using the
provided trim potentiometers (P1 and P2). The top and bottom
of the bridge are connected to VDD and VSS, respectively.
Pulse shaping is performed on this board before applying the
data to the
data input pin. The pulse widths
are set for 5 μs, representing the low level (0 V), and 80 μs,
representing the high level (>2.4 V). This adjustment is made
using Resistor RT0 and Resistor RT1. The trim potentiometers
are glued to their fixed positions.
Supply current can be monitored by using a resistor in place of
R7. Clamp voltage can be applied externally to a level or can be
set easily to V
DD
by placing a jumper from VCLAMP to VDD.
The SOIC/LFCSP socket is soldered for easy programming and
removal of the device. Pin 1 is the pin located in the upper left-
hand corner of the socket close to R7. Make sure that the device
is placed in the socket properly. See Figure 11 for the evaluation
board schematic.
SYSTEM REQUIREMENTS
The evaluation kit has the following system requirements:
Analog Devices, Inc., SDP-B or SDP-S system demonstration
platform (SDP) controller board (available for purchase
separately at
PC with available USB 2.0 port
Microsoft® Windows® operating system with administrator
access
COMMUNICATING WITH THE EVALUATION BOARD
The evaluation board connects to the Analog Devices SDP-B or
SDP-S board, which connects to the USB port of a PC.
Ensure that the evaluation software provided on the CD is
installed before connecting the SDP board and the evaluation
board.
HARDWARE REQUIREMENTS
The following equipment is required:
Power supplies
Voltage source
Voltmeter
BNCs and power cables
SDP board with USB mini-B cable
ADJUSTING FOR 0 V DIFFERENTIAL INPUT
Prior to initial hardware setup and output verification, complete
the following to adjust for differential input offset:
1.
Connect the positive input (high) of a voltmeter to −V
IN
dc.
2.
Connect the negative input (low) of the voltmeter to GND
of the power supply.
3.
Monitor the output (V
OUT
dc) voltmeter.
4.
Adjust trim Potentiometer P1 to be close to 0 V (−0.1 mV).
5.
Connect the positive input (high) of a voltmeter to +V
IN
dc.
6.
Connect the negative input (low) of the voltmeter to GND
of the power supply.
7.
Monitor the output (V
OUT
dc) voltmeter.
8.
Adjust trim Potentiometer P2 to be close to 0 V (0.1 mV).
