Specifications

Sensors
Current, light, and proximity sensing
www.digikey.com/maxim-industrial 81
Benefits
• Differential input/output configuration
minimizes harsh operating environ-
mental noise
– Processes signals above and below
ground using an input level-shifting
amplifier stage; is ideal for thermo-
couple applications
– Integrates an amplifier for a differential-
output configuration
• Integrated functionality reduces system
complexity, maximizes flexibility and
system robustness
– Optimized for high-signal bandwidth
– Programmable gain with the SPI controls:
0.2V/V, 1V/V, 10V/V, 20V/V, 30V/V, 40V/V,
60V/V, 80V/V, 119V/V, and 157V/V
– Embedded input protection to ±16V
– Integrated amplifier for
RC-programmable active filter
– Input offset-voltage compensation for
on-demand calibration
MAX9939
The MAX9939 is a differential-input, programmable-gain amplifier
(PGA). It features SPI™-programmable differential gains from 0.2V/V
to 157V/V; input offset-voltage compensation for on-demand cali-
bration; and an output amplifier that can be configured either as a
high-order active filter or to provide a differential output. Using an
input level-shifting amplifier stage, the MAX9939 processes signals
both above and below ground.
Improve system accuracy over temperature and minimize the effects of harsh
environmental noise
R
I
A
V
CC
V
CC
/2
20kΩ
20kΩ
V
CC
V
CC
/2
20kΩ
20kΩ
LVL
V
CC
V
CC
/2
20kΩ
20kΩ
10kΩ
10kΩ
10kΩ
INA+
INA-
B
R
F
0.1μF
1μF
V
CC
SCLK
SPI REGISTERS
DIN CS
GAIN
INPUT-
OFFSET-
VOLTAGE
TRIM
SHUTDOWN
10kΩ
10kΩ
ADC
OUTA
INB
OUTB
ASIC
CS
DOUT
SCLK
MAX9939
Functional diagram of the robust MAX9939 PGA.