19-6000; Rev 0; 10/11
MAX44251/MAX44252
20V, Ultra-Precision, Low-Noise Op Amps
General 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. This method constantly measures
and compensates the input offset, eliminating drift over
time and temperature and the effect of 1/f noise. These
dual and quad devices feature rail-to-rail outputs, oper-
ate from a single 2.7V to 20V supply, and consume only
1.15mA per channel, while providing 5.9nV/√Hz input-
referred voltage noise. The ICs are unity-gain stable with
a gain-bandwidth product of 10MHz.
With excellent specifications such as offset voltage of
6µV (max), drift of 19nV/°C (max), and 123nV
P-P
noise in
0.1Hz to 10Hz, the ICs are ideally suited for applications
requiring ultra-low noise and DC precision such as inter-
facing with pressure sensors, strain gauges, precision
weight scales, and medical instrumentation.
Benefits and Features
S
2.7V to 20V Power-Supply Range
S
Integrated EMI Filter
S
6µV Input Offset Voltage (max) at Room
Temperature
S
TCV
OS
of 19nV/°C (max)
S
Low 5.9nV/√Hz Input-Referred Voltage Noise
S
123nV
P-P
in 0.1Hz to 10Hz
S
Fast 400ns Settling Time
S
10MHz Gain-Bandwidth Product
S
Rail-to-Rail Output
S
High Accuracy Enables Precision Signal Chain
Acquisition
Applications
Strain Gauges
Pressure Transducers
Medical Instrumentation
Precision Instrumentation
Load Cell and Bridge Transducer Amplification
The ICs are available in 8-pin SOT23, 8-pin µMAX
M
,
and 14-pin SOIC packages and are rated over the
-40°C to +125°C temperature range.
Ordering Information
appears at end of data sheet.
Functional Diagrams
appear at end of data sheet.
For related parts and recommended products to use with this part,
refer to
www.maxim-ic.com/MAX44251.related.
Typical Operating Circuit
3.3V
20V
MAX44251
BUFFER
20V
R
50R
G
50R
G
20V
R
BUFFER
1.5V
R
V
IN-
20V
V
DD
BUFFER
V
IN+
V
REF
R
R
1
3V
V
OUT
MAX6126
V
DD
R
G
MAX11211
OUTPUT
V
SS
MICRO-
PROCESSOR
MAX44251
C
1
MAX44251
µMAX is a registered trademark of Maxim Integrated Products, Inc.
½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½
Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
MAX44251/MAX44252
20V, Ultra-Precision, Low-Noise Op Amps
ABSOLUTE MAXIMUM RATINGS
Supply Voltage (V
DD
to V
SS
).................................-0.3V to +22V
All Other Pins..................................(V
SS
- 0.3V) to (V
DD
+ 0.3V)
Short-Circuit Duration to Either Supply Rail ............................ 1s
Continuous Input Current (any pin)................................. ±20mA
Differential Input Voltage ...................................................... ±6V
Maximum Power Dissipation (T
A
= +70°C)
SOT23 (derate 9.1 mW/°C above +70°C) ...................727mW
µMAX (derate 4.5 mW/°C above +70°C) ....................362mW
SOIC (derate 8.3 mW/°C above +70°C) ..................666.7mW
Operating Temperature Range ........................ -40°C to +125NC
Junction Temperature .....................................................+150NC
Storage Temperature Range............................ -65°C to +150NC
Lead Temperature (soldering, 10s) .............................. +300NC
Soldering Temperature (reflow) .................................... +260NC
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional opera-
tion of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect device reliability.
PACKAGE THERMAL CHARACTERISTICS (Note 1)
SOT23
Junction-to-Ambient Thermal Resistance (Θ
JA
) ....... 196°C/W
Junction-to-Case Thermal Resistance (Θ
JC
) ...............70°C/W
µMAX
Junction-to-Ambient Thermal Resistance (Θ
JA
) ........221°C/W
Junction-to-Case Thermal Resistance (Θ
JC
) ...............42°C/W
SOIC
Junction-to-Ambient Thermal Resistance (Θ
JA
) ........120°C/W
Junction-to-Case Thermal Resistance (Θ
JC
) ...............37°C/W
Note 1:
Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-
layer board. For detailed information on package thermal considerations, refer to
www.maxim-ic.com/thermal-tutorial.
ELECTRICAL CHARACTERISTICS
(V
DD
= 10V,
V
SS
= 0V, V
IN+
= V
IN-
= V
DD
/2, R
L
= 10kI to V
DD
/2, T
A
= -40°C to +125°C, unless otherwise noted. Typical values are
at +25°C.) (Note 2)
PARAMETER
POWER SUPPLY
Supply Voltage Range
Power-Supply Rejection Ratio
(Note 3)
Quiescent Current per Amplifier
Power-Up Time
DC SPECIFICATIONS
Input Common-Mode Range
Common-Mode Rejection Ratio
(Note 3)
V
CM
CMRR
Guaranteed by CMRR test
T
A
= +25NC, V
CM
= -0.05V to (V
DD
-
1.5V)
-40NC < T
A
< +125NC
V
SS
-
0.05
133
130
140
V
DD
-
1.5
V
V
DD
PSRR
I
DD
t
ON
Guaranteed by PSRR
V
DD
= 2.7V to 20V, V
CM
= 0V
R
L
=
J
T
A
= +25NC
-40NC < T
A
< +125NC
25
2.7
140
145
1.15
1.55
1.75
20
V
dB
mA
Fs
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
dB
½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½
Maxim Integrated Products
2
MAX44251/MAX44252
20V, Ultra-Precision, Low-Noise Op Amps
ELECTRICAL CHARACTERISTICS (continued)
(V
DD
= 10V,
V
SS
= 0V, V
IN+
= V
IN-
= V
DD
/2, R
L
= 10kI to V
DD
/2, T
A
= -40°C to +125°C, unless otherwise noted. Typical values are
at +25°C.) (Note 2)
PARAMETER
Input Offset Voltage (Note 3)
Input Offset Voltage Drift
(Note 3)
Input Bias Current (Note 3)
Input Offset Current (Note 3)
SYMBOL
V
OS
TC V
OS
I
B
I
OS
A
VOL
250mV
P
V
OUT
P
V
DD
- 250mV,
R
L
= 10kI to
V
DD
/2
To V
DD
or V
SS
V
OL
V
OH
V
OUT
- V
SS
V
DD
- V
OUT
T
A
= +25NC
-40NC < T
A
< +125NC
Noncontinuous
R
L
= 10kI to V
DD
/2
R
L
= 2kI to V
DD
/2
R
L
= 10kI to V
DD
/2
R
L
= 2kI to V
DD
/2
145
136
96
12
45
18
71
5.9
123
0.6
2
10
C
L
= 20pF
A
V
= 1V/V, V
OUT
= 2V
P-P
No sustained oscillation, A
V
= 1V/V
V
OUT
= 2V
P-P
,
A
V
= +1V/V,
R
L
= 10kI to
V
DD
/2
f = 1kHz
f = 20kHz
60
8
500
-124
dB
-119
400
ns
25
85
37
135
mA
mV
mV
T
A
= +25NC
-40NC < T
A
< +125NC
400
154
dB
T
A
= +25NC
-40NC < T
A
< +125NC
5
200
CONDITIONS
MIN
TYP
3
MAX
6
7
19
1300
2400
UNITS
FV
nV/NC
pA
pA
Open-Loop Gain (Note 3)
Output Short-Circuit Current
Output Voltage Low
Output Voltage High
AC SPECIFICATIONS
Input Voltage-Noise Density
Input Voltage Noise
Input Current-Noise Density
Input Capacitance
Gain-Bandwidth Product
Phase Margin
Slew Rate
Capacitive Loading
i
N
C
IN
GBW
PM
SR
C
L
THD
e
N
f = 1kHz
0.1Hz < f < 10Hz
f = 1kHz
nV/√Hz
nV
P-P
pA/√Hz
pF
MHz
Degrees
V/Fs
pF
Total Harmonic Distortion
Settling Time
To 0.01%, V
OUT
= 2V step, A
V
= -1V/V
½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½
Maxim Integrated Products
3
MAX44251/MAX44252
20V, Ultra-Precision, Low-Noise Op Amps
ELECTRICAL CHARACTERISTICS
(V
DD
= 3.3V,
V
SS
= 0V, V
IN+
= V
IN-
= V
DD
/2, R
L
= 10kI to V
DD
/2, T
A
= -40°C to +125°C, unless otherwise noted. Typical values
are at +25°C.) (Note 2)
PARAMETER
POWER SUPPLY
Quiescent Current per Amplifier
Power-Up Time
DC SPECIFICATIONS
Input Common-Mode Range
Common-Mode Rejection Ratio
(Note 3)
Input Offset Voltage (Note 3)
Input Offset Voltage Drift
(Note 3)
Input Bias Current (Note 3)
Input Offset Current (Note 3)
V
CM
CMRR
Guaranteed by CMRR test
T
A
= +25NC, V
CM
= -0.05V to (V
DD
-
1.5V)
-40NC < T
A
< +125NC
V
OS
TC V
OS
I
B
I
OS
A
VOL
250mV
P
V
OUT
P
V
DD
- 250mV,
R
L
= 10kI to
V
DD
/2
To V
DD
or V
SS
V
OL
V
OH
V
OUT
- V
SS
V
DD
- V
OUT
T
A
= +25NC
-40NC < T
A
< +125NC
Noncontinuous
R
L
= 10kI to V
DD
/2
R
L
= 2kI to V
DD
/2
R
L
= 10kI to V
DD
/2
R
L
= 2kI to V
DD
/2
136
133
58
5
17
9
29
6.2
123
0.3
2
10
22
42
22
52
mA
mV
mV
T
A
= +25NC
-40NC < T
A
< +125NC
400
151
dB
T
A
= +25NC
-40NC < T
A
< +125NC
8
200
V
SS
-
0.05
120
117
3
5.5
6.5
18
1100
1200
FV
nV/NC
pA
pA
129
V
DD
-
1.5
V
I
DD
t
ON
R
L
=
J
T
A
= +25NC
-40NC < T
A
< +125NC
25
1.1
1.5
1.65
mA
Fs
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
dB
Open-Loop Gain (Note 3)
Output Short-Circuit Current
Output Voltage Low
Output Voltage High
AC SPECIFICATIONS
Input Voltage-Noise Density
Input Voltage Noise
Input Current-Noise Density
Input Capacitance
Gain-Bandwidth Product
i
N
C
IN
GBW
e
N
f = 1kHz
0.1Hz < f < 10Hz
f = 1kHz
nV/√Hz
nV
P-P
pA/√Hz
pF
MHz
½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½
Maxim Integrated Products
4
MAX44251/MAX44252
20V, Ultra-Precision, Low-Noise Op Amps
ELECTRICAL CHARACTERISTICS (continued)
(V
DD
= 3.3V,
V
SS
= 0V, V
IN+
= V
IN-
= V
DD
/2, R
L
= 10kI to V
DD
/2, T
A
= -40°C to +125°C, unless otherwise noted. Typical values are
at +25°C.) (Note 2)
PARAMETER
Phase Margin
Slew Rate
Capacitive Loading
SYMBOL
PM
SR
C
L
C
L
= 20pF
A
V
= 1V/V, V
OUT
= 1V
P-P
, 10% to 90%
No sustained oscillation, A
V
= 1V/V
V
OUT
= 1V
P-P
,
A
V
= +1V/V,
V
CM
= V
DD
/4,
R
L
= 10kI to
V
DD
/2
f = 1kHz
CONDITIONS
MIN
TYP
60
5
500
-124
dB
f = 20kHz
-100
200
ns
MAX
UNITS
Degrees
V/Fs
pF
Total Harmonic Distortion
THD
Settling Time
To 0.01%, V
OUT
= 1V step, A
V
= -1V/V
Note 2:
All devices are 100% production tested at T
A
= +25°C. Temperature limits are guaranteed by design.
Note 3:
Guaranteed by design.
Typical Operating Characteristics
(V
DD
= 10V, V
SS
= 0V, outputs have R
L
= 10kI to V
DD
/2. T
A
= +25NC, unless otherwise specified.)
OFFSET VOLTAGE HISTOGRAM
MAX44251 toc01
INPUT OFFSET VOLTAGE DRIFT HISTOGRAM
14
12
FREQUENCY (%)
10
8
6
4
2
MAX44251 toc02
SUPPLY CURRENT vs. SUPPLY VOLTAGE
T
A
= +125°C
T
A
= +85°C
1.2
SUPPLY CURRENT (mA)
MAX44251 toc03
25
20
FREQUENCY (%)
15
10
5
0
0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
OFFSET VOLTAGE (µV)
16
1.4
1.0
0.8
0.6
0.4
0.2
0
T
A
= +25°C
T
A
= 0°C
T
A
= -40°C
SUPPLY CURRENT
PER AMPLIFIER
0
5
10
15
20
25
0
-0.001
0
0.002
0.004
0.006
OFFSET VOLTAGE DRIFT (µV/°C)
0.001
0.003
0.005
SUPPLY VOLTAGE (V)
½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½
Maxim Integrated Products
5
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