Cirrus Logic CDB5461AU - Manual (Page 5)

CDB5461AU
DS661DB1 5
1.2.1 Analog Section
The CDB5461AU evaluation board provides screw-type terminals (J23, J27) to connect input signals to the voltage
and current channels. The screw terminals are labels as VIN+, VIN1, IIN+, and IIN-. A simple R-C network at each
channel input provides a simple anti-alias filter.
The evaluation board provides three voltage reference options for VREFIN to the CS5461A. The three voltage ref-
erence options include: VREFOUT from CS5461A, the on-board +2.5V reference, and external REF+ (screw termi-
nal J14). Table 1 and Table 2 illustrate the options available for VREFIN. With a jumper on J25 in the position labeled
VREFOUT, the reference is supplied by the on-chip voltage reference. With a jumper on J25 in the position labeled
VREF, the reference is supplied by an off-chip voltage reference.
Table 2 illustrates the options available for VREF. With a jumper on J12 in position LT1019, the LT1019 provides a
+2.5V reference (the LT1019 was chosen for its low drift - typically 5ppm/°C). By setting the jumper on J12 to position
REF+, an external voltage reference is supplied via screw terminal J14's REF+ input.
The three input signal options for the voltage (VIN±) and current (IIN±) channel input include: an external signal
(screw terminals J23 and J27), GND or VREF. Table 3 illustrates the options available. By installing jumpers on J17
to position VIN+, J22 to position VIN-, J24 to position IIN+ and J26 to position IIN-, the input voltage signal is supplied
from the screw terminals J23 and J27. With a jumper on J17, J22, J24 and J26 in the GND position, the inputs are
connected to analog ground (AGND). With a jumper on J17, J22, J24 and J26 in position
VREF
, the inputs are con-
nected to the reference voltage selected on J12.
Reference Description J25
VREFOUT
Selects on-Chip
Reference (25ppm/ ° C)
VREF
Selects External or
LT1019 Reference(J12)
Table 1. Internal Voltage Reference Selection for VREF
Reference Description J12
LT1019
Selects on-Board
LT1019 Reference
(5ppm/ ° C)
REF+
Selects External
Reference Source
(J6)
Table 2. External Voltage Reference Selection for VREF
O
O VREF
VREFIN
VREFOUT
(Default)
O
O VREF
VREFIN
VREFOUT
O VREF
O O VREF
LT1019
REF+
O VREF
O O VREF
LT1019
REF+
(Default)