AVAILABLE
EVALUATION KIT AVAILABLE
Functional Diagrams
Pin Configurations appear at end of data sheet.
Functional Diagrams continued at end of data sheet.
UCSP is a trademark of Maxim Integrated Products, Inc.
For pricing, delivery, and ordering information, please contact Maxim Direct
at 1-888-629-4642, or visit Maxim’s website at www.maximintegrated.com.
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 123nVP-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.
The ICs are available in 8-pin SOT23, 8-pin µMAXM,
and 14-pin SOIC packages and are rated over the
-40°C to +125°C temperature range.
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 TCVOS of 19nV/°C (max)
S Low 5.9nV/√Hz Input-Referred Voltage Noise
S 123nVP-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
Typical Operating Circuit
19-6000; Rev 1; 12/11
Ordering Information appears at end of data sheet.
For related parts and recommended products to use with this part,
refer to www.maxim-ic.com/MAX44251.related.
µMAX is a registered trademark of Maxim Integrated Products, Inc.
Functional Diagrams appear at end of data sheet.
20V
20V
20V
3.3V
3V
VDD
MICRO-
PROCESSOR
VOUT
50RG
50RG
RG
VREF
VDD
VSS
VIN-
VIN+
C1
BUFFER
BUFFER
MAX44251
MAX44251
MAX11211
MAX6126
MAX44251
R
R
20V
1.5V
BUFFER
R
R
R1
OUTPUT
MAX44251/MAX44252
20V, Ultra-Precision, Low-Noise Op Amps
Supply Voltage (VDD to VSS).................................-0.3V to +22V
All Other Pins ..................................(VSS - 0.3V) to (VDD + 0.3V)
Short-Circuit Duration to Either Supply Rail ............................ 1s
Continuous Input Current (any pin) ................................. ±20mA
Differential Input Voltage ...................................................... ±6V
Maximum Power Dissipation (TA = +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
SOT23
Junction-to-Ambient Thermal Resistance (ΘJA) ....... 196°C/W
Junction-to-Case Thermal Resistance (ΘJC) ...............70°C/W
µMAX
Junction-to-Ambient Thermal Resistance (ΘJA) ........221°C/W
Junction-to-Case Thermal Resistance (ΘJC) ...............42°C/W
SOIC
Junction-to-Ambient Thermal Resistance (ΘJA) ........120°C/W
Junction-to-Case Thermal Resistance (ΘJC) ...............37°C/W
ABSOLUTE MAXIMUM RATINGS
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.
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)
ELECTRICAL CHARACTERISTICS
(VDD = 10V, VSS = 0V, VIN+ = VIN- = VDD/2, RL = 10kI to VDD/2, TA = -40°C to +125°C, unless otherwise noted. Typical values are
at TA = +25°C.) (Note 2)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
POWER SUPPLY
Supply Voltage Range VDD Guaranteed by PSRR 2.7 20 V
Power-Supply Rejection Ratio
(Note 3) PSRR VDD = 2.7V to 20V, VCM = 0V 140 145 dB
Quiescent Current per Amplifier IDD RL = JTA = +25NC1.15 1.55 mA
-40NC < TA < +125NC1.75
Power-Up Time tON 25 Fs
DC SPECIFICATIONS
Input Common-Mode Range VCM Guaranteed by CMRR test VSS -
0.05
VDD -
1.5 V
Common-Mode Rejection Ratio
(Note 3) CMRR
TA = +25NC, VCM = -0.05V to (VDD -
1.5V) 133 140 dB
-40NC < TA < +125NC 130
MAX44251/MAX44252
Maxim Integrated
2
20V, Ultra-Precision, Low-Noise Op Amps
ELECTRICAL CHARACTERISTICS (continued)
(VDD = 10V, VSS = 0V, VIN+ = VIN- = VDD/2, RL = 10kI to VDD/2, TA = -40°C to +125°C, unless otherwise noted. Typical values are
at TA = +25°C.) (Note 2)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Input Offset Voltage (Note 3) VOS
TA = +25NC3 6 FV
-40NC < TA < +125NC7
Input Offset Voltage Drift
(Note 3) TC VOS 5 19 nV/NC
Input Bias Current (Note 3) IB
TA = +25NC200 1300 pA
-40NC < TA < +125NC2400
Input Offset Current (Note 3) IOS 400 pA
Open-Loop Gain (Note 3) A VOL
250mV P VOUT
P VDD - 250mV,
RL = 10kI to
VDD/2
TA = +25NC145 154
dB
-40NC < TA < +125NC136
Output Short-Circuit Current To VDD or VSS Noncontinuous 96 mA
Output Voltage Low VOL VOUT - VSS
RL = 10kI to VDD/2 12 25 mV
RL = 2kI to VDD/2 45 85
Output Voltage High VOH VDD - VOUT
RL = 10kI to VDD/2 18 37 mV
RL = 2kI to VDD/2 71 135
AC SPECIFICATIONS
Input Voltage-Noise Density eNf = 1kHz 5.9 nV/√Hz
Input Voltage Noise 0.1Hz < f < 10Hz 123 nVP-P
Input Current-Noise Density iNf = 1kHz 0.6 pA/√Hz
Input Capacitance CIN 2 pF
Gain-Bandwidth Product GBW 10 MHz
Phase Margin PM CL = 20pF 60 Degrees
Slew Rate SR AV = 1V/V, VOUT = 2VP-P 8V/Fs
Capacitive Loading CLNo sustained oscillation, AV = 1V/V 500 pF
Total Harmonic Distortion THD
VOUT = 2VP-P,
AV = +1V/V,
RL = 10kI to
VDD/2
f = 1kHz -124
dB
f = 20kHz -119
Settling Time To 0.01%, VOUT = 2V step, AV = -1V/V 400 ns
MAX44251/MAX44252
Maxim Integrated
3
20V, Ultra-Precision, Low-Noise Op Amps
ELECTRICAL CHARACTERISTICS
(VDD = 3.3V, VSS = 0V, VIN+ = VIN- = VDD/2, RL = 10kI to VDD/2, TA = -40°C to +125°C, unless otherwise noted. Typical values
are at TA = +25°C.) (Note 2)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
POWER SUPPLY
Quiescent Current per Amplifier IDD RL = JTA = +25NC1.1 1.5 mA
-40NC < TA < +125NC1.65
Power-Up Time tON 25 Fs
DC SPECIFICATIONS
Input Common-Mode Range VCM Guaranteed by CMRR test VSS -
0.05
VDD -
1.5 V
Common-Mode Rejection Ratio
(Note 3) CMRR
TA = +25NC, VCM = -0.05V to (VDD -
1.5V) 120 129 dB
-40NC < TA < +125NC 117
Input Offset Voltage (Note 3) VOS
TA = +25NC3 5.5 FV
-40NC < TA < +125NC6.5
Input Offset Voltage Drift
(Note 3) TC VOS 8 18 nV/NC
Input Bias Current (Note 3) IB
TA = +25NC200 1100 pA
-40NC < TA < +125NC1200
Input Offset Current (Note 3) IOS 400 pA
Open-Loop Gain (Note 3) AVOL
250mV P VOUT
P VDD - 250mV,
RL = 10kI to
VDD/2
TA = +25NC136 151
dB
-40NC < TA < +125NC133
Output Short-Circuit Current To VDD or VSS Noncontinuous 58 mA
Output Voltage Low VOL VOUT - VSS
RL = 10kI to VDD/2 5 22 mV
RL = 2kI to VDD/2 17 42
Output Voltage High VOH VDD - VOUT
RL = 10kI to VDD/2 9 22 mV
RL = 2kI to VDD/2 29 52
AC SPECIFICATIONS
Input Voltage-Noise Density eNf = 1kHz 6.2 nV/√Hz
Input Voltage Noise 0.1Hz < f < 10Hz 123 nVP-P
Input Current-Noise Density iNf = 1kHz 0.3 pA/√Hz
Input Capacitance CIN 2 pF
Gain-Bandwidth Product GBW 10 MHz
MAX44251/MAX44252
Maxim Integrated
4
20V, Ultra-Precision, Low-Noise Op Amps
ELECTRICAL CHARACTERISTICS (continued)
(VDD = 3.3V, VSS = 0V, VIN+ = VIN- = VDD/2, RL = 10kI to VDD/2, TA = -40°C to +125°C, unless otherwise noted. Typical values are
at TA = +25°C.) (Note 2)
Typical Operating Characteristics
(VDD = 10V, VSS = 0V, outputs have RL = 10kI to VDD/2. TA = +25NC, unless otherwise specified.)
Note 2: All devices are 100% production tested at TA = +25°C. Temperature limits are guaranteed by design.
Note 3: Guaranteed by design.
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Phase Margin PM CL = 20pF 60 Degrees
Slew Rate SR AV = 1V/V, VOUT = 1VP-P, 10% to 90% 5 V/Fs
Capacitive Loading CLNo sustained oscillation, AV = 1V/V 500 pF
Total Harmonic Distortion THD
VOUT = 1VP-P,
AV = +1V/V,
VCM = VDD/4,
RL = 10kI to
VDD/2
f = 1kHz -124
dB
f = 20kHz -100
Settling Time To 0.01%, VOUT = 1V step, AV = -1V/V 200 ns
OFFSET VOLTAGE HISTOGRAM
MAX44251 toc01
OFFSET VOLTAGE (µV)
PERCENT OCCURRENCE (%)
4.54.03.02.0 3.51.5 2.51.00.5
10
5
15
20
25
30
35
40
45
50
55
60
65
70
75
0
0 5.55.0
INPUT OFFSET VOLTAGE DRIFT HISTOGRAM
MAX44251 toc02
OFFSET VOLTAGE DRIFT (µV/°C)
PERCENT OCCURRENCE (%)
0.0050.0040.002 0.0030 0.001-0.001
5
10
15
20
25
30
35
40
45
0
0.006
SUPPLY CURRENT vs. SUPPLY VOLTAGE
MAX44251 toc03
SUPPLY VOLTAGE (V)
SUPPLY CURRENT (mA)
2015105
0.2
0.4
0.6
0.8
1.0
1.2
1.4
0
02
5
TA = +85°C
TA = +25°C TA = 0°C
TA = -40°C
SUPPLY CURRENT
PER AMPLIFIER
TA = +125°C
MAX44251/MAX44252
Maxim Integrated
5
20V, Ultra-Precision, Low-Noise Op Amps
Typical Operating Characteristics (continued)
(VDD = 10V, VSS = 0V, outputs have RL = 10kI to VDD/2. TA = +25NC, unless otherwise specified.)
SUPPLY CURRENT vs. TEMPERATURE
MAX44251 toc04
TEMPERATURE (°C)
SUPPLY CURRENT (mA)
12510050 750 25-25
1.08
1.10
1.12
1.14
1.16
1.18
1.20
1.22
1.24
1.26
1.28
1.06
-50 150
SUPPLY CURRENT
PER AMPLIFIER
INPUT OFFSET VOLTAGE
vs. INPUT COMMON MODE
MAX44251 toc05
INPUT COMMON VOLTAGE (V)
VOS (µV)
8642
1
2
3
4
5
6
0
01
0
INPUT OFFSET VOLTAGE
vs. TEMPERATURE
MAX44251 toc06
VOS (µV)
1
2
3
4
5
6
0
TEMPERATURE (°C)
10050 75025-25-50 125
INPUT BIAS CURRENT
vs. COMMON-MODE VOLTAGE
MAX44251 toc07
INPUT COMMON-MODE VOLTAGE (V)
INPUT BIAS CURRENT (pA)
2 310-1-2-3-4
-1000
-500
0
500
1000
1500
2000
-1500
-5 4
IBIAS-
IBIAS+
TA = +125°C
TA = -40°C
TA = +25°C
INPUT BIAS CURRENT
vs. TEMPERATURE
MAX44251 toc08
IBIAS (pA)
-1000
-750
-500
-250
0
250
500
750
1000
-1250
TEMPERATURE (°C)
12510050 75025-25-50 150
NEGATIVE IBIAS
POSITIVE IBIAS
COMMON-MODE REJECTION RATIO
vs. FREQUENCY
MAX44251 toc09
FREQUENCY (Hz)
CMRR (dB)
1M100k1k 10k10 1001
0
20
40
60
80
100
120
140
160
-20
0.1 100M10M
MAX44251/MAX44252
Maxim Integrated
6
20V, Ultra-Precision, Low-Noise Op Amps
Typical Operating Characteristics (continued)
(VDD = 10V, VSS = 0V, outputs have RL = 10kI to VDD/2. TA = +25NC, unless otherwise specified.)
OUTPUT VOLTAGE HIGH
vs. OUTPUT SOURCE CURRENT (VDD - VOH)
MAX44251 toc10
OUTPUT SOURCE CURRENT (mA)
OUTPUT VOLTAGE HIGH (mV)
8642
100
200
300
400
500
600
0
01
0
OUTPUT VOLTAGE LOW
vs. OUTPUT SINK CURRENT
MAX44251 toc11
OUTPUT SINK CURRENT (mA)
OUTPUT VOLTAGE LOW (mV)
8642
50
100
150
200
250
300
0
01
0
OUTPUT VOLTAGE SWING HIGH
vs. TEMPERATURE
MAX44251 toc12
TEMPERATURE (°C)
12510050 75025-25-50 150
VOH (mV)
5
10
15
20
25
30
35
0
RL = 10kI to VDD/2
2
4
6
8
10
12
14
16
18
0
OUTPUT VOLTAGE SWING LOW
vs. TEMPERATURE
MAX44251 toc13
TEMPERATURE (°C)
12510050 75025-25-50 150
VOL (mV)
RL = 10kI to VDD/2
OPEN-LOOP GAIN vs. FREQUENCY
MAX44251 toc14
FREQUENCY (Hz)
OPEN-LOOP GAIN (dB)
1M100k1k 10k10 10010.1 10M 100M
160
180
140
120
100
80
60
40
20
0
-20
-40
-60
INPUT VOLTAGE NOISE vs. FREQUENCY
MAX44251 toc15
FREQUENCY (Hz)
INPUT VOLTAGE NOISE (nV/√Hz)
10k1k100
5
10
15
20
25
30
0
10 100k
INPUT VOLTAGE 0.1Hz TO 10Hz NOISE
MAX44251 toc16
1s/div
0.2µV/div
INPUT CURRENT NOISE vs. FREQUENCY
MAX44251 toc17
FREQUENCY (Hz)
INPUT CURRENT NOISE (pA/√Hz)
1k10010
1
2
3
4
5
6
0
1 10k
SMALL-SIGNAL RESPONSE
MAX44251 toc18
FREQUENCY (Hz)
MAGNITUDE (dB)
10M1M10k 100k100 1k10
-16
-14
-12
-10
-8
-6
-4
-2
0
2
-18
1 100M
VIN = 100mVP-P
MAX44251/MAX44252
Maxim Integrated
7
20V, Ultra-Precision, Low-Noise Op Amps
Typical Operating Characteristics (continued)
(VDD = 10V, VSS = 0V, outputs have RL = 10kI to VDD/2. TA = +25NC, unless otherwise specified.)
MAGNITUDE (dB)
-45
-40
-35
-30
-25
-20
-15
-10
-5
0
5
-50
LARGE-SIGNAL RESPONSE
MAX44251 toc19
FREQUENCY (Hz)
1M100k1k 10k10 10010.1 100M10M
VIN = 2VP-P
POWER-UP TIME
MAX44251 toc22
TIME (10µs/div)
25µs
VDD = VSS = 0V
VDD = 5V
VSS = 5V
VOLTAGE (1V/div)
0V
0V
SUPPLY
VOLTAGE
(5V/div)
VOFFSET
(10mV/div)
1k100 10k
STABILITY vs. CAPACITIVE AND
RESISTIVE LOAD IN PARALLEL WITH CL
MAX44251 toc25
CAPACITIVE LOAD (pF)
RESISTIVE LOAD (kI)
10
20
30
40
50
60
70
80
90
100
0
STABLE UNSTABLE
SMALL-SIGNAL STEP RESPONSE
vs. TIME
MAX44251 toc20
TIME (2µs/div)
AV = 1V/V
VIN = 100mVP-P
INPUT
OUTPUT
VOLTAGE (100mV/div)
TOTAL HARMONIC DISTORTION
vs. FREQUENCY
MAX44251 toc23
FREQUENCY (Hz)
MAGNITUDE (dB)
10k1k
-135
-130
-125
-120
-115
-110
-105
-100
-140
100 100k
STABILITY vs. CAPACITIVE AND
RISO IN SERIES WITH CLOAD
MAX44251 toc26
CAPACITIVE LOAD (pF)
RISO (I)
10k1k
1
2
3
4
5
6
7
8
0
100 100k
STABLE
UNSTABLE
LARGE-SIGNAL STEP RESPONSE
vs. TIME
MAX44251 toc21
TIME (2µs/div)
AV = 1V/V
VIN = 2VP-P
INPUT
OUTPUT
VOLTAGE (1V/div)
TOTAL HARMONIC DISTORTION
vs. INPUT VOLTAGE
MAX44251 toc24
INPUT VOLTAGE (V)
MAGNITUDE (dB)
1.751.501.251.000.750.50
-120
-100
-80
-60
-40
-20
0
-140
0.25 2.00
VCC = 3.3V
MAX44251/MAX44252
Maxim Integrated
8
20V, Ultra-Precision, Low-Noise Op Amps
Pin Description
Pin Configurations
PIN NAME FUNCTION
SOT23 µMAX SOIC
1 1 1 OUTA Channel A Output
2 2 2 INA- Channel A Negative Input
3 3 3 INA+ Channel A Positive Input
4 4 11 VSS Negative Supply Voltage
5 5 5 INB+ Channel B Positive Input
6 6 6 INB- Channel B Negative Input
7 7 7 OUTB Channel B Output
8 8 4 VDD Positive Supply Voltage
— — 8 OUTC Channel C Output
— — 9 INC- Channel C Negative Input
— — 10 INC+ Channel C Positive Input
— — 12 IND+ Channel D Positive Input
— — 13 IND- Channel D Negative Input
— — 14 OUTD Channel B Output
TOP VIEW
IND+
VSS
VDD
1
2
14
13
OUTD
IND-INA-
INA+
OUTA
3
4
12
11
INC-
OUTCOUTB
51
0INC+INB+
INB- 6
7
9
8
+
14 SOIC
MAX44252
1
2
3
4
8
7
6
5
VDD
OUTB
INB-
INB+VSS
INA+
INA-
OUTA
8 µMAX
+
MAX44251
8 SOT23
MAX44251
VSS
1
2INA-
INA+
OUTA
3
4
INB-
INB+
8
7
VDD
OUTB
6
5
+
MAX44251/MAX44252
Maxim Integrated
9
20V, Ultra-Precision, Low-Noise Op Amps
Detailed Description
The MAX44251/MAX44252 are high-precision amplifiers
that have less than 3FV of typical input-referred offset
and low flicker noise. These characteristics are achieved
through an autozeroing technique that samples and finds
repeating patterns of signal to cancel the input offset volt-
age and 1/f noise of the amplifier.
Autozero
The ICs feature an autozero circuit that allows the devices
to achieve less than 6FV (max) of input offset voltage at
room temperature and eliminate the 1/f noise.
Noise Suppression
Flicker noise, inherent in all active devices, is inversely
proportional to frequency presented. Charges at the
oxide-silicon interface that are trapped-and-released by
MOSFET oxide occurs at low frequency more often. For
this reason, flicker noise is also called 1/f noise.
Electromagnetic interference (EMI) noise occurs at high-
er frequency that results in malfunction or degradation of
electrical equipment.
The ICs have an input EMI filter to avoid the output get-
ting affected by radio frequency interference. The EMI
filter composed of passive devices presents significant
higher impedance to higher frequency.
High Supply Voltage Range
The ICs feature 1.15mA current consumption per channel
and a voltage supply range from either 2.7V to 20V single
supply or ±1.35V to ±10V split supply.
Applications Information
The ICs are ultra-high-precision operational amplifiers with
a high supply voltage range designed for load cell, medi-
cal instrumentation and precision instrument applications.
These devices are also designed to interface with pres-
sure transducers and are ideal for precision weight scale
application as shown in Figure 1.
ADC Buffer Amplifier
The MAX44251/MAX44252's low input offset voltage, low
noise, and fast settling time make these amplifiers ideal
for ADC buffers. Weigh scales are one application that
often require a low-noise, high-voltage amplifier in front
of an ADC. Figure 1 details an example of a load cell and
amplifier driven from the same Q10V supplies, along with
the MAX11211 18-bit delta sigma ADC. Load cells pro-
duce a very small voltage change at their outputs, there-
fore driving the excitation source with a higher voltage
produces a wider dynamic range that can be measured
at the ADC inputs.
The MAX11211 ADC operates from a single 2.7V to 3.6V
analog supply, offers 18-bit noise-free resolution and
0.86mW power dissipation. The MAX11211 also offers
> 100dB rejection at 50Hz and 60Hz. This ADC is part of
a family of 16-, 18-, 20-, and 24-bit delta sigma ADCs with
high precision and < 1mW power dissipation.
The MAX44251/MAX44252's low input offset voltage and
low noise allow a gain circuit prior to the MAX11211 with-
out losing any dynamic range at the ADC.
Figure 1. Weight Scale Application Circuit
20V
20V
20V
3.3V
3V
VDD
MICRO-
PROCESSOR
VOUT
50RG
50RG
RG
VREF
VDD
VSS
VIN-
VIN+
C1
BUFFER
BUFFER
MAX44251
MAX44251
MAX11211
MAX6126
MAX44251
R
R
20V
1.5V
BUFFER
R
R
R1
OUTPUT
MAX44251/MAX44252
Maxim Integrated
10
20V, Ultra-Precision, Low-Noise Op Amps
Error Budget Example
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.
Precision Low-Side Current Sensing
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, VOUT equal to ILOAD
x RSENSE x R2/R1.
Figure 2. Low-Side Current Sensing
Ordering Information
+Denotes a lead(Pb)-free/RoHS-compliant package.
Chip Information
PROCESS: BiCMOS
Functional Diagrams
PART TEMP RANGE PIN-
PACKAGE
TOP
MARK
MAX44251AKA+ -40NC to +125NC8 SOT23 AERC
MAX44251AUA+ -40NC to +125NC 8 FMAX —
MAX44252ASD+ -40NC to +125NC14 SOIC —
VSUPPLY
OUT
ILOAD
RSENSE
R1
R2
MAX44251
MAX44252
5
6
7
10
9
8
INB-
INB+VSS
1
2
8
7
VDD
OUTBINA-
INA+
OUTA
TOP VIEW
3
4
6
5
MAX44251
+
IND+
VSS
VDD
INB+
1
2
14
13
OUTD
IND-INA-
INA+
INB-
OUTB
OUTA
3
4
12
11
INC+
INC-
OUTC
MAX44252
+
MAX44251/MAX44252
Maxim Integrated
11
20V, Ultra-Precision, Low-Noise Op Amps
Package Information
For the latest package outline information and land patterns (footprints), go to www.maxim-ic.com/packages. Note that a “+”, “#”, or
“-” in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains
to the package regardless of RoHS status.
PACKAGE TYPE PACKAGE CODE OUTLINE NO. LAND PATTERN
8 SOT23 K8+5 21-0078 90-0176
8 FMAX U8+1 21-0036 90-0092
14 SOIC S14M+5 21-0041 90-0096
MAX44251/MAX44252
Maxim Integrated
12
20V, Ultra-Precision, Low-Noise Op Amps
Package Information (continued)
For the latest package outline information and land patterns (footprints), go to www.maxim-ic.com/packages. Note that a “+”, “#”, or
“-” in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains
to the package regardless of RoHS status.
α
α
MAX44251/MAX44252
Maxim Integrated
13
20V, Ultra-Precision, Low-Noise Op Amps
Package Information (continued)
For the latest package outline information and land patterns (footprints), go to www.maxim-ic.com/packages. Note that a “+”, “#”, or
“-” in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains
to the package regardless of RoHS status.
MAX44251/MAX44252
Maxim Integrated
14
20V, Ultra-Precision, Low-Noise Op Amps
Revision History
REVISION
NUMBER
REVISION
DATE DESCRIPTION PAGES
CHANGED
0 10/11 Initial release —
1 12/11 Released the MAX44252 and updated the Typical Operating Characteristics. 5, 6, 11
MAX44251/MAX44252
Maxim Integrated 160 Rio Robles, San Jose, CA 95134 USA 1-408-601-1000
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied.
Maxim reserves the right to change the circuitry and specifications without notice at any time. The parametric values (min and max limits) shown in the Electrical
Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance.
© Maxim Integrated The Maxim logo and Maxim Integrated are trademarks of Maxim Integrated Products, Inc.
