Specifications

www.digikey.com/maxim-industrial 11
Programmable logic controllers (PLCs)
Analog input function
Benefits
• No extra components needed for a wide
range of sensor-input voltages
– 0.2V/V to 157V/V SPI-programmable
gains
• Enhanced SNR performance reduces
effects of unwanted signal noise
– Differential-input and differential-output
configuration improves the signal-
conditioning resolution and accuracy
• Improved signal-path robustness
– Inputs can withstand ±16V transients
MAX9939
The MAX9939 is a precision, differential-input PGA ideal for condi-
tioning wide-dynamic-range signals like those found in automotive
current sense, medical instrumentation, and industrial data-
acquisition applications. The MAX9939 features SPI-programmable
differential gains from 0.2V/V to 157V/V, input V
OS
compensation, and an
output amplifier that can be configured either as a high-order active
filter or to provide a differential output.
Reduce component count with precision differential PGA that supports positive and
negative sensor signals
The MAX9939 uses matched resistors to provide a wide range of gains.
ADC
µC
V
CC
/2
V
CC
/2
+
+
–
–
SPI
M
RELAY
Input common-mode voltage
extends 1V below ground
even at high gain—ideal for
power-ground voltage spikes
Internal matched
resistors for high
CMRR and low-gain
tempco
Input switches for
on-command V
OS
calibration by
rmware
Internal V
REF
= V
CC
/2
allows bidirectional
current sense
Integrated output op amp
for active lter applications
or differential outputs
5MHz SPI bus to set
gain from 0.2 to 156!
MAX9939