Cirrus Logic CDB5464U - Manual (Page 4)

CDB5464U
4 DS847DB1
1.3 Analog Section
The CDB5464U evaluation board provides screw-type terminals (J23, J27, & J28) to connect input signals
to the voltage and current channels. The screw terminals are labels as VIN1-, VIN1+, IIN1+, IIN1-, and
IIN2+, IIN2-. An 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 CS5464. The three volt-
age reference options include: VREFOUT from CS5464, the on-board +2.5V reference, and external
REF+ (screw terminal 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 5 ppm/°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 (VIN1±) and current (IIN1±, IIN2±) channels input include:
an external signal (screw terminals J23, J27, and J28), GND, or VREF. Table3 illustrates the options avail-
able. By installing jumpers on J17 to position VIN1-, J22 to position VIN1+, J24 to position IIN1+, J26 to
position IIN1-, J20 to position IIN2+, and J19 to position IIN2-, the input voltage signal is supplied from the
screw terminals J23, J27, and J28. With a jumper on J17, J22, J24, J26, J20, and J19 in the GND position,
Reference Description J25
VREFOUT
Selects On-chip
Reference (25 ppm/ ° 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
(5 ppm/ ° C)
REF+
Selects External
Reference Source
(J14)
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)