Maxim MAX44252 20v, ultra-precision, low-noise op amp Datasheet

19-6000; Rev 0; 10/11
MAX44251/MAX44252
20V, Ultra-Precision, Low-Noise Op Amps
General Description
Benefits and Features
The MAX44251/MAX44252 are 20V, ultra-precision, lownoise, 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, operate from a single 2.7V to 20V supply, and consume only
1.15mA per channel, while providing 5.9nV/√Hz inputreferred voltage noise. The ICs are unity-gain stable with
a gain-bandwidth product of 10MHz.
S 2.7V to 20V Power-Supply Range
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 interfacing with pressure sensors, strain gauges, precision
weight scales, and medical instrumentation.
S Rail-to-Rail Output
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 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 µMAXM,
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
3V
MAX44251
R
BUFFER
R1
20V
VDD
50RG
BUFFER
MICROPROCESSOR
MAX11211 OUTPUT
VIN-
20V
R
BUFFER
VDD
VREF
VIN+
R
50RG
MAX6126
20V
R
RG
VOUT
VSS
MAX44251
1.5V
C1
MAX44251
µMAX is a registered trademark of Maxim Integrated Products, Inc.
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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 (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
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation 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 (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
Note 1: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a fourlayer board. For detailed information on package thermal considerations, refer to www.maxim-ic.com/thermal-tutorial.
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 +25°C.) (Note 2)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
20
V
POWER SUPPLY
Supply Voltage Range
Power-Supply Rejection Ratio
(Note 3)
VDD
PSRR
Quiescent Current per Amplifier
IDD
Power-Up Time
tON
Guaranteed by PSRR
2.7
VDD = 2.7V to 20V, VCM = 0V
140
RL = J
145
1.15
TA = +25NC
dB
1.55
1.75
-40NC < TA < +125NC
25
mA
Fs
DC SPECIFICATIONS
Input Common-Mode Range
Common-Mode Rejection Ratio
(Note 3)
VCM
CMRR
Guaranteed by CMRR test
VSS 0.05
TA = +25NC, VCM = -0.05V to (VDD 1.5V)
133
-40NC < TA < +125NC
130
VDD 1.5
140
V
dB
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MAX44251/MAX44252
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 +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)
Open-Loop Gain (Note 3)
SYMBOL
VOS
CONDITIONS
MIN
TA = +25NC
Output Short-Circuit Current
6
7
TA = +25NC
5
19
200
1300
2400
-40NC < TA < +125NC
IOS
A­VOL
MAX
3
-40NC < TA < +125NC
TC VOS
IB
TYP
400
TA = +25NC
To VDD or VSS
Noncontinuous
96
RL = 10kI to VDD/2
12
25
RL = 2kI to VDD/2
45
85
RL = 10kI to VDD/2
18
37
RL = 2kI to VDD/2
71
135
Output Voltage Low
VOL
VOUT - VSS
Output Voltage High
VOH
VDD - VOUT
FV
nV/NC
pA
pA
250mV P VOUT
P VDD - 250mV,
RL = 10kI to
VDD/2
145
UNITS
154
dB
-40NC < TA < +125NC
136
mA
mV
mV
AC SPECIFICATIONS
Input Voltage-Noise Density
eN
Input Voltage Noise
Input Current-Noise Density
Input Capacitance
Gain-Bandwidth Product
iN
f = 1kHz
5.9
nV/√Hz
0.1Hz < f < 10Hz
123
nVP-P
f = 1kHz
0.6
pA/√Hz
2
pF
CIN
10
MHz
Phase Margin
PM
CL = 20pF
60
Degrees
Slew Rate
SR
AV = 1V/V, VOUT = 2VP-P
8
V/Fs
Capacitive Loading
CL
No sustained oscillation, AV = 1V/V
500
pF
VOUT = 2VP-P,
AV = +1V/V,
RL = 10kI to
VDD/2
f = 1kHz
-124
f = 20kHz
-119
Total Harmonic Distortion
Settling Time
GBW
THD
dB
To 0.01%, VOUT = 2V step, AV = -1V/V
400
ns
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MAX44251/MAX44252
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 +25°C.) (Note 2)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
1.1
1.5
UNITS
POWER SUPPLY
Quiescent Current per Amplifier
IDD
Power-Up Time
tON
RL = J
TA = +25NC
1.65
-40NC < TA < +125NC
25
mA
Fs
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)
Open-Loop Gain (Note 3)
VCM
CMRR
VOS
Guaranteed by CMRR test
VSS 0.05
TA = +25NC, VCM = -0.05V to (VDD 1.5V)
120
-40NC < TA < +125NC
117
TA = +25NC
Output Short-Circuit Current
5.5
8
18
200
1100
1200
-40NC < TA < +125NC
400
250mV P VOUT
P VDD - 250mV,
RL = 10kI to
VDD/2
TA = +25NC
136
-40NC < TA < +125NC
133
To VDD or VSS
Noncontinuous
Output Voltage Low
VOL
VOUT - VSS
Output Voltage High
VOH
VDD - VOUT
V
dB
6.5
-40NC < TA < +125NC
IOS
AVOL
129
3
TA = +25NC
TC VOS
IB
VDD 1.5
FV
nV/NC
pA
pA
151
dB
58
mA
RL = 10kI to VDD/2
5
22
RL = 2kI to VDD/2
17
42
RL = 10kI to VDD/2
9
22
RL = 2kI to VDD/2
29
52
mV
mV
AC SPECIFICATIONS
Input Voltage-Noise Density
eN
Input Voltage Noise
Input Current-Noise Density
Input Capacitance
Gain-Bandwidth Product
iN
f = 1kHz
6.2
nV/√Hz
0.1Hz < f < 10Hz
123
nVP-P
f = 1kHz
0.3
pA/√Hz
CIN
2
pF
GBW
10
MHz
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MAX44251/MAX44252
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 +25°C.) (Note 2)
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
CL
No sustained oscillation, AV = 1V/V
500
pF
Total Harmonic Distortion
VOUT = 1VP-P,
AV = +1V/V,
VCM = VDD/4,
RL = 10kI to
VDD/2
THD
Settling Time
f = 1kHz
-124
dB
f = 20kHz
-100
To 0.01%, VOUT = 1V step, AV = -1V/V
200
ns
Note 2: All devices are 100% production tested at TA = +25°C. Temperature limits are guaranteed by design.
Note 3: Guaranteed by design.
Typical Operating Characteristics
(VDD = 10V, VSS = 0V, outputs have RL = 10kI to VDD/2. TA = +25NC, unless otherwise specified.)
10
10
8
6
4
5
0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
OFFSET VOLTAGE (µV)
TA = +85°C
1.0
TA = +25°C
TA = 0°C
TA = -40°C
0.8
0.6
0.4
SUPPLY CURRENT
PER AMPLIFIER
0.2
2
0
TA = +125°C
1.2
SUPPLY CURRENT (mA)
12
15
1.4
MAX44251 toc02
MAX44251 toc01
14
FREQUENCY (%)
FREQUENCY (%)
20
SUPPLY CURRENT vs. SUPPLY VOLTAGE
INPUT OFFSET VOLTAGE DRIFT HISTOGRAM
16
MAX44251 toc03
OFFSET VOLTAGE HISTOGRAM
25
0
0
-0.001
0.001
0.003
0.005
0
0.002
0.004
0.006
OFFSET VOLTAGE DRIFT (µV/°C)
0
5
10
15
20
25
SUPPLY VOLTAGE (V)
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MAX44251/MAX44252
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.)
INPUT OFFSET VOLTAGE
vs. INPUT COMMON MODE
1.24
5
1.22
5
4
VOS (µV)
1.18
1.16
1.14
1.12
SUPPLY CURRENT
PER AMPLIFIER
1.08
VOS (µV)
4
1.20
1.10
3
-50
-25
0
25
50
75
2
1
1
100 125 150
0
0
2
4
6
8
10
-50
-25
0
25
50
75
100
TEMPERATURE (°C)
INPUT COMMON VOLTAGE (V)
TEMPERATURE (°C)
INPUT BIAS CURRENT
vs. INPUT COMMON-MODE VOLTAGE
INPUT BIAS CURRENT
vs. TEMPERATURE
COMMON-MODE REJECTION RATIO
vs. FREQUENCY
150
750
NEGATIVE IBIAS
100
POSITIVE IBIAS
500
160
140
120
250
0
-50
-100
0
-250
-500
POSITIVE IBIAS
-150
-750
-200
-1000
-250
2
4
6
VCM (V)
100
CMRR (dB)
IBIAS (pA)
50
8
10
125
MAX44251 toc09
200
MAX44251 toc08
1000
MAX44251 toc07
250
0
3
2
0
1.06
IBIAS (pA)
6
MAX44251 toc05
1.26
SUPPLY CURRENT (mA)
6
MAX44251 toc04
1.28
INPUT OFFSET VOLTAGE
vs. TEMPERATURE
MAX44251 toc06
SUPPLY CURRENT vs. TEMPERATURE
80
60
40
NEGATIVE IBIAS
20
0
-1250
-20
-50
-25
0
25
50
75
TEMPERATURE (°C)
100 125 150
0.1
1
10 100 1k 10k 100k 1M 10M 100M
FREQUENCY (Hz)
����������������������������������������������������������������� Maxim Integrated Products 6
MAX44251/MAX44252
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.)
COMMON-MODE REJECTION RATIO
vs. TEMPERATURE
OUTPUT VOLTAGE SWING HIGH
vs. TEMPERATURE
POWER-SUPPLY REJECTION RATIO
vs. FREQUENCY
140
120
30
25
100
80
VOH (mV)
PSRR (dB)
60
40
20
80
25
50
75
100
0.1
125
1
10 100 1k 10k 100k 1M 10M 100M
OUTPUT VOLTAGE SWING LOW
vs. TEMPERATURE
OPEN-LOOP GAIN vs. FREQUENCY
OPEN-LOOP GAIN (dB)
14
12
10
8
6
4
140
120
100
80
60
40
20
0
-20
-40
RL = 10kI to VDD/2
0
25
50
75
1
15
10
5
INPUT CURRENT NOISE vs. FREQUENCY
10k
100k
SMALL-SIGNAL RESPONSE
MAX44251 toc17
5
4
0
-2
MAGNITUDE (dB)
INPUT CURRENT NOISE (pA/√Hz)
1k
2
3
2
-4
-6
-8
-10
-12
-14
1
VIN = 100mVP-P
-16
1s/div
100
10
FREQUENCY (Hz)
6
0.2µV/div
100 125 150
20
FREQUENCY (Hz)
MAX44251 toc16
75
25
10 100 1k 10k 100k 1M 10M 100M
TEMPERATURE (°C)
INPUT VOLTAGE 0.1Hz TO 10Hz NOISE
50
0
0.1
100 125 150
25
30
-60
0
-25
0
INPUT VOLTAGE NOISE vs. FREQUENCY
MAX44251 toc14
16
-50
-25
TEMPERATURE (°C)
180
160
MAX44251 toc13
18
2
-50
FREQUENCY (Hz)
MAX44251 toc15
0
INPUT VOLTAGE NOISE (nV/√Hz)
-25
RL = 10kI to VDD/2
0
-40
TEMPERATURE (°C)
VOL (mV)
5
VCM = 0V
-20
-50
15
10
0
60
20
MAX44251 toc18
CMRR (dB)
100
120
MAX44251 toc12
140
35
MAX44251 toc11
160
MAX44251 toc10
160
0
-18
1
10
100
FREQUENCY (Hz)
1k
10k
1
10
100
1k
10k 100k 1M 10M 100M
FREQUENCY (Hz)
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MAX44251/MAX44252
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.)
LARGE-SIGNAL RESPONSE
SMALL-SIGNAL STEP RESPONSE
vs. TIME
MAX44251 toc19
0
-5
MAX44251 toc20
MAX44251 toc21
AV = 1V/V
VIN = 100mVP-P
-10
-15
VOLTAGE (100mV/div)
MAGNITUDE (dB)
LARGE-SIGNAL STEP RESPONSE
vs. TIME
-20
-25
-30
-35
-40
AV = 1V/V
VIN = 2VP-P
INPUT
INPUT
VOLTAGE (1V/div)
5
OUTPUT
OUTPUT
VIN = 2VP-P
-45
-50
10 100 1k 10k 100k 1M 10M 100M
FREQUENCY (Hz)
TIME (2µs/div)
TIME (2µs/div)
POWER-UP TIME
TOTAL HARMONIC DISTORTION
vs. FREQUENCY
TOTAL HARMONIC DISTORTION
vs. INPUT VOLTAGE
VDD = 5V
-105
MAGNITUDE (dB)
VOLTAGE (1V/div)
0V
VOFFSET
(10mV/div)
-115
-120
-125
-120
100
1k
100k
10k
-140
0.25
FREQUENCY (Hz)
90
80
0.50
0.75
1.00
1.25
1.50
1.75
2.00
INPUT VOLTAGE (V)
STABILITY vs. CAPACITIVE AND
RISO IN SERIES WITH CLOAD
8
MAX44251 toc25
100
RESISTIVE LOAD (kI)
-80
-135
STABILITY vs. CAPACITIVE AND
RESISTIVE LOAD IN PARALLEL WITH CL
7
60
UNSTABLE
40
STABLE
6
70
STABLE
-60
-100
TIME (10µs/div)
50
-40
-130
-140
25µs
VCC = 3.3V
-20
MAGNITUDE (dB)
-110
VSS = 5V
0
MAX44251 toc26
VDD = VSS = 0V
MAX44251 toc24
-100
MAX44251 toc22
SUPPLY
VOLTAGE
(5V/div)
0V
MAX44251 toc23
1
RISO (I)
0.1
5
4
3
30
UNSTABLE
2
20
1
10
0
0
100
1k
CAPACITIVE LOAD (pF)
10k
100
1k
10k
100k
CAPACITIVE LOAD (pF)
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MAX44251/MAX44252
20V, Ultra-Precision, Low-Noise Op Amps
Pin Configurations
TOP VIEW
OUTA 1
+
OUTA
1
8 VDD
INA-
2
7 OUTB
INA+
3
6 INB-
VSS
4
5 INB+
MAX44251
+
INA- 2
OUTA
1
INA-
2
INA+
3
VSS
4
+
8
MAX44251
VDD
7
OUTB
6
INB-
5
INB+
8 µMAX
8 SOT23
14 OUTD
MAX44252
13 IND-
INA+ 3
12 IND+
VDD 4
11 VSS
INB+ 5
10 INC+
INB- 6
9 INC-
OUTB 7
8 OUTC
14 SOIC
Pin Description
PIN
NAME
FUNCTION
SOT23
µMAX
SOIC
1
1
1
OUTA
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
8
8
4
VDD
—
—
8
OUTC
—
—
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 A Output
Channel B Output
Positive Supply Voltage
Channel C Output
Channel B Output
����������������������������������������������������������������� Maxim Integrated Products 9
MAX44251/MAX44252
20V, Ultra-Precision, Low-Noise Op Amps
Detailed Description
Applications Information
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 voltage and 1/f noise of the amplifier.
The ICs are ultra-high-precision operational amplifiers with
a high supply voltage range designed for load cell, medical instrumentation and precision instrument applications.
These devices are also designed to interface with pressure transducers and are ideal for precision weight scale
application as shown in Figure 1.
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 higher frequency that results in malfunction or degradation of
electrical equipment.
The ICs have an input EMI filter to avoid the output getting 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.
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 produce a very small voltage change at their outputs, therefore 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 without losing any dynamic range at the ADC.
3.3V
20V
3V
MAX44251
R
BUFFER
R1
20V
VDD
50RG
BUFFER
MICRO
PROCESSOR
MAX11211 OUTPUT
VIN-
20V
R
BUFFER
VDD
VREF
VIN+
R
50RG
MAX6126
20V
R
RG
VOUT
1.5V
VSS
MAX44251
C1
MAX44251
Figure 1. Weight Scale Application Circuit
���������������������������������������������������������������� Maxim Integrated Products 10
MAX44251/MAX44252
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 current-sensing applications. Figure 2 shows the ICs in
a low-side current-sense configuration. This circuit produces an accurate output voltage, VOUT equal to ILOAD
x RSENSE x R2/R1.
Chip Information
PROCESS: BiCMOS
Ordering Information
TEMP RANGE
PINPACKAGE
TOP
MARK
MAX44251AKA+
-40NC to +125NC
8 SOT23
AERC
MAX44251AUA+
-40NC to +125NC
8 FMAX
—
MAX44252ASD+*
-40NC to +125NC
14 SOIC
—
PART
+Denotes a lead(Pb)-free/RoHS-compliant package.
*Future product—contact factory for availability.
Functional Diagrams
TOP VIEW
+
OUTA 1
8
VDD
INA- 2
7
OUTB
3
6
INB-
VSS 4
5
INB+
INA+
MAX44251
+
VSUPPLY
R2
ILOAD
R1
OUT
RSENSE
MAX44251
MAX44252
OUTA 1
14 OUTD
INA- 2
13 IND-
INA+
12 IND+
3
VDD 4
MAX44252
11 VSS
INB+ 5
10 INC+
INB- 6
9
INC-
OUTB 7
8
OUTC
Figure 2. Low-Side Current Sensing
���������������������������������������������������������������� Maxim Integrated Products 11
MAX44251/MAX44252
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
���������������������������������������������������������������� Maxim Integrated Products 12
MAX44251/MAX44252
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
���������������������������������������������������������������� Maxim Integrated Products 13
MAX44251/MAX44252
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.
���������������������������������������������������������������� Maxim Integrated Products 14
MAX44251/MAX44252
20V, Ultra-Precision, Low-Noise Op Amps
Revision History
REVISION
NUMBER
REVISION
DATE
0
10/11
DESCRIPTION
Initial release
PAGES
CHANGED
—
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.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
©
2011 Maxim Integrated Products
15
Maxim is a registered trademark of Maxim Integrated Products, Inc.