Rainbow Electronics MAX44252 User Manual

19-6000; Rev 0; 10/11

MAX44251/MAX44252

20V, Ultra-Precision, Low-Noise Op Amps

General Description

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.

With excellent specifications such as offset voltage of
6µV (max), drift of 19nV/°C (max), and 123nV

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.

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.

noise in

P-P

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 123nV

in 0.1Hz to 10Hz

P-P

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

3.3V

20V

MAX44251

1.5V

R

20V

BUFFER

MAX44251

V

IN+

V

IN-

V

DD

MAX11211

V

SS

V

REF

OUTPUT

20V

R

G

BUFFER

50R

50R

20V

BUFFER

G

G

MAX44251

R

R

R

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.

3V

V

R

C

1

OUT

1

MAX6126

V

DD

MICRO-

PROCESSOR

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

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

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

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 four-

layer board. For detailed information on package thermal considerations, refer to www.maxim-ic.com/thermal-tutorial.

ELECTRICAL CHARACTERISTICS

(VDD = 10V, VSS = 0V, V
at +25°C.) (Note 2)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

POWER SUPPLY

Supply Voltage Range V

Power-Supply Rejection Ratio
(Note 3)

Quiescent Current per Amplifier I

Power-Up Time t

DC SPECIFICATIONS

Input Common-Mode Range V

Common-Mode Rejection Ratio
(Note 3)

IN+

= V

= VDD/2, RL = 10kI to VDD/2, TA = -40°C to +125°C, unless otherwise noted. Typical values are

IN-

DD

PSRR VDD = 2.7V to 20V, VCM = 0V 140 145 dB

DD

ON

CM

CMRR

Guaranteed by PSRR 2.7 20 V

RL = J

Guaranteed by CMRR test

TA = +25NC, VCM = -0.05V to (VDD -

1.5V)

-40NC < TA < +125NC

TA = +25NC

-40NC < TA < +125NC

VSS -

0.05

133 140

130

1.15 1.55

1.75

25

VDD -

1.5

mA

Fs

V

dB

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MAX44251/MAX44252

20V, Ultra-Precision, Low-Noise Op Amps

ELECTRICAL CHARACTERISTICS (continued)

(VDD = 10V, VSS = 0V, V
at +25°C.) (Note 2)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

Input Offset Voltage (Note 3) V

Input Offset Voltage Drift
(Note 3)

Input Bias Current (Note 3) I

Input Offset Current (Note 3) I

Open-Loop Gain (Note 3) A

Output Short-Circuit Current To VDD or V

Output Voltage Low V

Output Voltage High V

AC SPECIFICATIONS

Input Voltage-Noise Density e

Input Voltage Noise 0.1Hz < f < 10Hz 123 nV

Input Current-Noise Density i

Input Capacitance C

Gain-Bandwidth Product GBW 10 MHz

Phase Margin PM CL = 20pF 60 Degrees

Slew Rate SR AV = 1V/V, V

Capacitive Loading C

Total Harmonic Distortion THD

Settling Time To 0.01%, V

IN+

= V

= VDD/2, RL = 10kI to VDD/2, TA = -40°C to +125°C, unless otherwise noted. Typical values are

IN-

3 6

7

5 19

200 1300

2400

400 pA

12 25

45 85

18 37

71 135

2 pF

8

TC V

OS

VOL

OS

B

OL

OH

N

N

IN

L

TA = +25NC

-40NC < TA < +125NC

OS

TA = +25NC

-40NC < TA < +125NC

250mV P V
P VDD - 250mV,
RL = 10kI to
VDD/2

V

- V

OUT

VDD - V

SS

OUT

OUT

SS

TA = +25NC

-40NC < TA < +125NC

145 154

136

Noncontinuous 96 mA

RL = 10kI to VDD/2

RL = 2kI to VDD/2

RL = 10kI to VDD/2

RL = 2kI to VDD/2

f = 1kHz 5.9

f = 1kHz 0.6

= 2V

OUT

P-P

No sustained oscillation, AV = 1V/V 500 pF

V

= 2V

OUT

AV = +1V/V,
RL = 10kI to
VDD/2

,

P-P

f = 1kHz -124

f = 20kHz -119

= 2V step, AV = -1V/V 400 ns

OUT

nV/NC

mV

mV

nV/√Hz

pA/√Hz

V/Fs

FV

pA

dB

P-P

dB

����������������������������������������������������������������� Maxim Integrated Products 3

MAX44251/MAX44252

20V, Ultra-Precision, Low-Noise Op Amps

ELECTRICAL CHARACTERISTICS

(VDD = 3.3V, VSS = 0V, V
are at +25°C.) (Note 2)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

POWER SUPPLY

Quiescent Current per Amplifier I

Power-Up Time t

DC SPECIFICATIONS

Input Common-Mode Range V

Common-Mode Rejection Ratio
(Note 3)

Input Offset Voltage (Note 3) V

Input Offset Voltage Drift
(Note 3)

Input Bias Current (Note 3) I

Input Offset Current (Note 3) I

Open-Loop Gain (Note 3) A

Output Short-Circuit Current To VDD or V

Output Voltage Low V

Output Voltage High V

AC SPECIFICATIONS

Input Voltage-Noise Density e

Input Voltage Noise 0.1Hz < f < 10Hz 123 nV

Input Current-Noise Density i

Input Capacitance C

Gain-Bandwidth Product GBW 10 MHz

IN+

= V

= VDD/2, RL = 10kI to VDD/2, TA = -40°C to +125°C, unless otherwise noted. Typical values

IN-

DD

ON

CM

CMRR

OS

TC V

B

OS

VOL

OL

OH

N

N

IN

RL = J

Guaranteed by CMRR test

TA = +25NC, VCM = -0.05V to (VDD -

1.5V)

-40NC < TA < +125NC

TA = +25NC

-40NC < TA < +125NC

OS

TA = +25NC

-40NC < TA < +125NC

250mV P V
P VDD - 250mV,
RL = 10kI to
VDD/2

V

- V

OUT

SS

VDD - V

OUT

f = 1kHz 6.2

f = 1kHz 0.3

TA = +25NC

-40NC < TA < +125NC

OUT

TA = +25NC

-40NC < TA < +125NC

Noncontinuous 58 mA

SS

RL = 10kI to VDD/2

RL = 2kI to VDD/2

RL = 10kI to VDD/2

RL = 2kI to VDD/2

VSS -

0.05

120 129

117

136 151

133

1.1 1.5

1.65

25

VDD -

1.5

3 5.5

6.5

8 18

200 1100

1200

400 pA

5 22

17 42

9 22

29 52

2 pF

nV/NC

nV/√Hz

pA/√Hz

mA

Fs

V

dB

FV

pA

dB

mV

mV

P-P

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MAX44251/MAX44252

02

20V, Ultra-Precision, Low-Noise Op Amps

ELECTRICAL CHARACTERISTICS (continued)

(VDD = 3.3V, VSS = 0V, V
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, V

Capacitive Loading C

Total Harmonic Distortion THD

IN+

= V

= VDD/2, RL = 10kI to VDD/2, TA = -40°C to +125°C, unless otherwise noted. Typical values are

IN-

= 1V

OUT

No sustained oscillation, AV = 1V/V 500 pF

L

V

OUT

= 1V

P-P

,

AV = +1V/V,

, 10% to 90% 5

P-P

f = 1kHz -124

VCM = VDD/4,
RL = 10kI to
VDD/2

f = 20kHz -100

V/Fs

dB

Settling Time To 0.01%, V

= 1V step, AV = -1V/V 200 ns

OUT

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.)

OFFSET VOLTAGE HISTOGRAM

25

20

15

10

FREQUENCY (%)

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)

MAX44251 toc01

INPUT OFFSET VOLTAGE DRIFT HISTOGRAM

16

14

12

10

8

6

FREQUENCY (%)

4

2

0

-0.00100.001

OFFSET VOLTAGE DRIFT (µV/°C)

0.002

0.003

0.004

0.005

MAX44251 toc02

0.006

SUPPLY CURRENT vs. SUPPLY VOLTAGE

1.4

TA = +125°C

1.2

1.0

0.8

0.6

SUPPLY CURRENT (mA)

0.4

0.2

TA = +25°C

0

SUPPLY VOLTAGE (V)

TA = 0°C

SUPPLY CURRENT

TA = +85°C

TA = -40°C

PER AMPLIFIER

2015105

MAX44251 toc03

5

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MAX44251/MAX44252

TEMPERATURE (°C)

01

01

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

1.28

1.26

1.24

1.22

1.20

1.18

1.16

1.14

SUPPLY CURRENT (mA)

1.12

1.10

1.08

1.06

-50 150

SUPPLY CURRENT

PER AMPLIFIER

INPUT BIAS CURRENT

vs. INPUT COMMON-MODE VOLTAGE

250

200

(pA)

BIAS

I

150

100

50

0

-50

-100

-150

-200

-250

NEGATIVE I

POSITIVE I

VCM (V)

BIAS

BIAS

INPUT OFFSET VOLTAGE

vs. INPUT COMMON MODE

6

(µV)

OS

V

5

4

3

2

1

0

8642

INPUT COMMON VOLTAGE (V)

MAX44251 toc04

12510050 750 25-25

MAX44251 toc05

0

(µV)

OS

V

6

5

4

3

2

1

0

INPUT BIAS CURRENT

vs. TEMPERATURE

1000

750

MAX44251 toc07

500

250

0

(pA)

BIAS

-250

I

-500

-750

-1000

8642

-1250

0

POSITIVE I

BIAS

NEGATIVE I

BIAS

TEMPERATURE (°C)

12510050 75025-25-50 150

MAX44251 toc08

160

140

120

100

80

60

CMRR (dB)

40

20

0

-20

INPUT OFFSET VOLTAGE

vs. TEMPERATURE

10050 75025-25-50 125

TEMPERATURE (°C)

COMMON-MODE REJECTION RATIO

vs. FREQUENCY

0.1 100M10M
FREQUENCY (Hz)

1M100k1k 10k10 1001

MAX44251 toc06

MAX44251 toc09

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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.)

COMMON-MODE REJECTION RATIO

vs. TEMPERATURE

160

140

120

CMRR (dB)

100

80

60

TEMPERATURE (°C)

OUTPUT VOLTAGE SWING LOW

vs. TEMPERATURE

18

16

14

12

10

(mV)

OL

8

V

6

4

2

0

TEMPERATURE (°C)

10050 75025-25-50 125

RL = 10kI to VDD/2

12510050 75025-25-50 150

MAX44251 toc10

MAX44251 toc13

POWER-SUPPLY REJECTION RATIO

vs. FREQUENCY

160

140

120

100

80

60

PSRR (dB)

40

20

0

-20

-40

0.1 100M10M
FREQUENCY (Hz)

OPEN-LOOP GAIN vs. FREQUENCY

180
160
140
120
100

80
60
40
20

OPEN-LOOP GAIN (dB)

0

-20

-40

-60

FREQUENCY (Hz)

VCM = 0V

1M100k1k 10k10 1001

1M100k1k 10k10 10010.1 10M 100M

MAX44251 toc11

(mV)

OH

V

MAX44251 toc14

INPUT VOLTAGE NOISE (nV/√Hz)

OUTPUT VOLTAGE SWING HIGH

vs. TEMPERATURE

35

30

25

20

15

10

5

0

TEMPERATURE (°C)

RL = 10kI to VDD/2

INPUT VOLTAGE NOISE vs. FREQUENCY

30

25

20

15

10

5

0

10 100k

FREQUENCY (Hz)

10k1k100

MAX44251 toc12

12510050 75025-25-50 150

MAX44251 toc15

INPUT VOLTAGE 0.1Hz TO 10Hz NOISE

1s/div

MAX44251 toc16

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0.2µV/div

INPUT CURRENT NOISE vs. FREQUENCY

6

5

4

3

2

INPUT CURRENT NOISE (pA/√Hz)

1

0

1 10k

FREQUENCY (Hz)

2

SMALL-SIGNAL RESPONSE

0

MAX44251 toc17

-2

-4

-6

-8

-10

MAGNITUDE (dB)

-12

-14

VIN = 100mV

-16

1k10010

-18
1 100M

P-P

FREQUENCY (Hz)

MAX44251 toc18

10M1M10k 100k100 1k10

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.)

5

0

-5

-10

-15

-20

-25

-30

MAGNITUDE (dB)

-35

-40

-45

-50

SUPPLY

VOLTAGE

(5V/div)

0V

0V

V

OFFSET

(10mV/div)

LARGE-SIGNAL RESPONSE

FREQUENCY (Hz)

POWER-UP TIME

VDD = VSS = 0V

VOLTAGE (1V/div)

TIME (10µs/div)

25µs

VIN = 2V

1M100k1k 10k10 10010.1 100M10M

VDD = 5V

VSS = 5V

P-P

MAX44251 toc22

MAX44251 toc19

MAGNITUDE (dB)

SMALL-SIGNAL STEP RESPONSE

vs. TIME

AV = 1V/V

= 100mV

V

IN

P-P

INPUT

OUTPUT

VOLTAGE (100mV/div)

TIME (2µs/div)

TOTAL HARMONIC DISTORTION

vs. FREQUENCY

-100

-105

-110

-115

-120

-125

-130

-135

-140
100 100k

FREQUENCY (Hz)

10k1k

MAX44251 toc20

MAX44251 toc23

LARGE-SIGNAL STEP RESPONSE

vs. TIME

AV = 1V/V

= 2V

V

IN

P-P

INPUT

VOLTAGE (1V/div)

OUTPUT

TIME (2µs/div)

TOTAL HARMONIC DISTORTION

vs. INPUT VOLTAGE

0

VCC = 3.3V

-20

-40

-60

-80

MAGNITUDE (dB)

-100

-120

-140

0.25 2.00
INPUT VOLTAGE (V)

MAX44251 toc21

MAX44251 toc24

1.751.501.251.000.750.50

STABILITY vs. CAPACITIVE AND

RESISTIVE LOAD IN PARALLEL WITH C

100

90

80

70

60

STABLE UNSTABLE

50

40

RESISTIVE LOAD (kI)

30

20

10

0

1k100 10k

CAPACITIVE LOAD (pF)

L

MAX44251 toc25

(I)

ISO

R

STABILITY vs. CAPACITIVE AND

IN SERIES WITH C

R

8

ISO

7

STABLE

6

5

4

3

2

1

0

100 100k

CAPACITIVE LOAD (pF)

LOAD

UNSTABLE

10k1k

MAX44251 toc26

����������������������������������������������������������������� Maxim Integrated Products 8

TOP VIEW

51

OUTA

INA+

V

SS

1

2INA-

3

4

+

MAX44251

8 SOT23

MAX44251/MAX44252

20V, Ultra-Precision, Low-Noise Op Amps

Pin Configurations

+

87V

6

5

DD

OUTB

INB-

INB+

OUTA

INA-

INA+

1

OUTA

2

+

1

2

MAX44251

3

4

SS

8

V

DD

7

OUTB

6

INB-

5

INB+V

8 µMAX

INA+

V

DD

INB- 6

MAX44252

3

4

7

14 SOIC

1413OUTD

IND-INA-

IND+

12

V

11

SS

0 INC+INB+

9

INC-

8

OUTCOUTB

PIN

SOT23 µMAX SOIC

NAME FUNCTION

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 V

SS

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 V

DD

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

Pin Description

����������������������������������������������������������������� Maxim Integrated Products 9

MAX44251/MAX44252

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 volt­age 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 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.

Applications Information

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.

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.

20V

R

G

BUFFER

50R

50R

20V

BUFFER

G

G

20V

Figure 1. Weight Scale Application Circuit

���������������������������������������������������������������� Maxim Integrated Products 10

MAX44251

MAX44251

3.3V

3V

V

R

R

1.5V

20V

BUFFER

MAX44251

V

IN+

V

IN-

V

DD

MAX11211

V

V

REF

OUTPUT

SS

C

R

R

OUT

R

1

MAX6126

1

V

DD

MICRO

PROCESSOR

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, V
x R

SENSE

x R2/R1.

equal to I

OUT

LOAD

Chip Information

PROCESS: BiCMOS

Ordering Information

PART TEMP RANGE

MAX44251AKA+

MAX44251AUA+
MAX44252ASD+*

-40NC to +125NC

-40NC to +125NC 8 FMAX

-40NC to +125NC

+Denotes a lead(Pb)-free/RoHS-compliant package.
*Future product—contact factory for availability.

Functional Diagrams

TOP VIEW

OUTA

INA+

+

1

2

3

4

SS

MAX44251

PIN­PACKAGE

TOP

MARK

8 SOT23 AERC

—

14 SOIC —

87V

DD

OUTBINA-

INB-

6

INB+V

5

V

SUPPLY

I

LOAD

R

1

R

SENSE

Figure 2. Low-Side Current Sensing

���������������������������������������������������������������� Maxim Integrated Products 11

R

2

MAX44251
MAX44252

OUT

OUTA

INA+

V

INB+

INB-

OUTB

+

1

2

3

4

DD

5

6

7

MAX44252

1413OUTD

IND-INA-

IND+

12

V

11

SS

10

INC+

9

INC-

8

OUTC

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

8 FMAX

14 SOIC S14M+5

U8+1

21-0078 90-0176
21-0036 90-0092
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

0 10/11 Initial release —

REVISION

DATE

DESCRIPTION

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 15

©

2011 Maxim Integrated Products Maxim is a registered trademark of Maxim Integrated Products, Inc.