Specifications

8 Maxim Industrial Solutions
Programmable logic controllers (PLCs)
Analog input function
should be rejected before the gain
stages. This is best accomplished
using Maxim’s PGAs or differential
amplifiers with a high common-
mode rejection ratio (CMRR). Maxim
has a variety of laser-trimmed,
matching resistor-dividers for precise
gain and attenuation; there are also
trimmable calibration potentiometers
for programmability, and ADCs with
differential inputs and PGAs inte-
grated in a single IC.
Lowpass or bandpass filtering
before the ADC sampling network is
necessary for anti-aliasing require-
ments and for rejecting noise sources
at other frequencies. PLC designers
have a choice between active filters
implemented with op amps or
switched-capacitor filters with a
very sharp (up to 8-pole) rolloff and
a programmable cut-off frequency.
Maxim provides a selection of 5th-
and 8th-order, switched-capacitor
and continuous-time filters ideal for
anti-aliasing.