MAX44252 Maxim, MAX44252 Datasheet - Page 11

• Manufacturer Part Number: MAX44252
• Description: The MAX44251/MAX44252 are 20V, ultra-precision, low-noise, low-drift amplifiers that offer near-zero DC offset and drift through the use of patented autocorrelating zeroing techniques
• Manufacturer: Maxim

When using the ICs as an ADC buffer in strain gauge
application, the temperature drift should be taken into
consideration to determine maximum input signal. A
typical strain gauge has sensitivity specification of just
2mV/V at rated out load. This means that when the strain
gauge load cell is powered with 10V, the full-scale output
voltage is 20mV. In this application, both offset voltage
and drift are critical parameters that directly affect the
accuracy of measurement. Even though offset voltage
could be calibrated out, its drift over temperature is still
a problem.
The ICs, with a typical offset drift of 5nV/°C, guarantee
that the drift over a 10°C range is only 50nV. Setting this
equal to 0.5 LSB in a 18-bit system yields a full-scale
range of 13mV. With a single 10V supply, an acceptable
closed-loop gain of 770V/V provides sufficient gain while
maintaining headroom.
The ICs’ autozero feature produces ultra-low offset
voltage and drift, making them ideal for precision cur-
rent-sensing applications. Figure 2 shows the ICs in
a low-side current-sense configuration. This circuit pro-
duces an accurate output voltage, V
x R
Figure 2. Low-Side Current Sensing
SENSE
x R
Precision Low-Side Current Sensing
I
LOAD
R
SENSE
2
/R
V
SUPPLY
1
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.
20V, Ultra-Precision, Low-Noise Op Amps
R
1
Error Budget Example
R
2
MAX44251
MAX44252
OUT
equal to I
OUT
LOAD
+Denotes a lead(Pb)-free/RoHS-compliant package.
PROCESS: BiCMOS
MAX44251AKA+
MAX44251AUA+
MAX44252ASD+
MAX44251/MAX44252
PART
TOP VIEW
OUTA
OUTA
OUTB
INA+
INA+
INB+
INA-
INA-
INB-
V
V
DD
SS
-40NC to +125NC
-40NC to +125NC
-40NC to +125NC
TEMP RANGE
1
2
4
1
2
4
5
6
7
3
3
Ordering Information
Functional Diagrams
+
+
MAX44252
Chip Information
MAX44251
PIN-
PACKAGE
8 SOT23
8 FMAX
14 SOIC
14
13
12
11
10
6
9
8
8
7
5
V
OUTB
INB-
INB+
OUTD
IND-
IND+
V
INC+
INC-
OUTC
DD
SS
MARK
AERC
TOP
—
—