Analog Devices ADSP-21992 EZ-KIT LITE System Manual page 49

Two AD8044 quad operational amplifiers (
analog interface and are configured as summing unity-gain stages.
used to interface the
to buffer the
VIN4
Precision 10 Kohm resistors for input and feedback ensure accurate gain
matching of all channels. In addition, 47 pF feedback capacitors provide
simple low-pass filtering with a very high cut-off frequency (339 kHz) on
all analog inputs.
The analog inputs are applied to the ADSP-21992 in a single-ended fash-
ion, so that the inverting inputs to the sample-and-hold amplifiers of the
ADSP-21992 (
reference voltage. A representation of the analog interface circuit for one
of the ADC channels is shown in
at the end of this document, each analog input stage also contains a small
RC filter at the operational amplifier output.
V1
VREF
Figure 3-2. One Analog Interface Circuit
ADSP-21992 EZ-KIT Lite Evaluation System Manual
, ,
VIN0 VIN1 VIN2
, , , and
VIN5 VIN6
and ) are connected to a buffered version of the
ASHAN BSHAN
C
R
+AVDD
R
-
AD8044
R
+
R
-AVDD
EZ-KIT Lite Hardware Reference
and
A5 A6
, and analog inputs.
VIN3
inputs.
VIN7
Figure 3-2. As shown in the schematics
VIN1
) are used for the
is
A5
is used
A6
3-5