MAX1400 Maxim, MAX1400 Datasheet - Page 31

• Manufacturer Part Number: MAX1400
• Description: %V / 18-Bit / Low-Power / Multichannel / Oversampling Sigma-Delta ADC
• Manufacturer: Maxim

Connect the differential inputs of the MAX1400 to the
bridge network of the strain gauge. In Figure 16, the
analog positive supply voltage powers the bridge net-
work and the MAX1400 along with its reference voltage.
The on-chip PGA allows the MAX1400 to handle an
analog input voltage range as low as 20mV full scale.
The differential inputs of the part allow this analog input
range to have an absolute value anywhere between
AGND and V+.
Figure 16. Strain-Gauge Application with MAX1400
DUMMY
ACTIVE
GAUGE
GAUGE
R
REF
ANALOG SUPPLY
R
R
REFIN+
REFIN-
AIN1
AIN2
CALIBRATION
______________________________________________________________________________________
ADDITIONAL
CHANNELS
ANALOG
AND
+5V, 18-Bit, Low-Power, Multichannel,
Strain Gauge Operation
SWITCHING
NETWORK
Oversampling (Sigma-Delta) ADC
MUXOUT+
MUXOUT-
AGND
V+
ADCIN+
ADCIN-
BUFFER
BUFFER
MAX1400
AGND
Figure 17 shows a connection from a thermocouple to
the MAX1400. In this application, the MAX1400 is oper-
ated in its buffered mode to allow large decoupling
capacitors on the front end. These decoupling capaci-
tors eliminate any noise pickup form the thermocouple
leads. When the MAX1400 is operated in buffered
mode, it has a reduced common-mode range. In order
to place the differential voltage from the thermocouple
on a suitable common-mode voltage, the AIN2 input of
the MAX1400 is biased at the reference voltage, +2.5V.
V+
PGA
DGND
DAC
V
DD
MODULATOR
Temperature Measurement
DIVIDER
INTERFACE
CONTROL
DIGITAL
FILTER
AND
CLOCK
GEN
CLKIN
CLKOUT
SCLK
DIN
DOUT
INT
CS
RESET
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