CDB5471 Datasheet, PDF (8/26 Pages) Cirrus Logic – Evaluation Board and Software

CDB5471
Name
Function Description
Default Setting Default Jumpers
HDR15
HDR16
HDR17
HDR18
Controls the
source
for the
CS5471
XIN clock
input.
Set to on-board 4.000
MHz crystal (U1).
This header should always be shorted.
Short this header
Determines whether the main analog supply will be
powered from the A- post, or from the regulated 3V
voltage (generated from the +5V_IN) post input.
Choose whether the digital circuitry will be powered
by main analog supply, or powered by separate dig-
ital supply (through VD+ post).
Set to A-
Set to main analog
supply
Table 2. Default Header Settings (Continued)
O O EXT XIN
O O DGND
O O 4.0096 MHz
OSC
OO
O O +5V_IN
O O A+
VD+ O O
V+ O O
2.3.1 Analog Inputs
Refer to Figure 2. The settings on the 14 analog in-
put headers (2 headers per channel) which are des-
ignated as HDR10 through HDR13, determine
which of the input lines will carry a signal, and
which input lines may be grounded. They can be
configured to accept either a single-ended or differ-
ential signal. Using the voltage channel as an ex-
ample (see Figure 2), note that HDR10 sets the
input to the positive side of the first voltage channel
input (VIN1+ pin). HDR13 sets the input to the
negative side of the first voltage channel input
(VIN1- pin). In a single-ended input configuration,
HDR13 would be set to the “AGND” setting, and
HDR10 would be set to “VIN1+” and would con-
duct the single-ended signal. In a differential input
configuration, HDR13 would be set to “VIN1-”
and HDR10 would be set to “VIN1+” and this pair
of inputs would form the differential input pair into
the VIN1+ and VIN1- pins of the CS5471.
WARNING: DANGER! One of the possible ap-
plications for the CS5471 includes data acquisition
for a power metering system. However, the user
should not attempt to directly connect any leads
from a high-voltage power line to the evaluation
board inputs, even if the current/voltage levels are
gain reduced by resistive dividers and/or shunts.
Because the ground terminal of the parallel cable
(from the PC) is near or at earth ground potential,
the ground node on the evaluation board will also
be forced to earth ground potential. Serious dam-
age and even personal injury can occur if a “hot”
voltage main is connected to any point on the eval-
uation board, including the analog input connec-
tors. Such power line signals must be isolated by
current/voltage transformers and reduced in mag-
nitude before they can be safely applied to the eval-
uation board.
Several patch-circuit areas are provided near the
voltage/current input headers, in case the user
wants to connect special sensor circuitry to the an-
alog inputs (such as transformers, shunt resistors,
etc., for sensory the voltage/current on a single-
phase power line). For the input channel, a Shunt
Resistor or Current Transformer can be mounted in
these areas and connections can be made to current-
channel input pair. Likewise, the three channels, a
Voltage Divider or Voltage Transformer can be
connected to the CS5471’s voltage input pair. Note
from Figure 2 that a simple R-C network filters
each sensor’s output to reduce any interference
picked up by the input leads. The 3 dB corner of the
filter is approximately 50 kHz differential and
common mode.
Note that the CDB5471 Evaluation Board is also
used as the evaluation board for the CS5451 A/D
converter, which is a 6-channel version of the
CS5471. The user can use this board to the evalu-
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DS480DB1