Download MAX44244/MAX44245/MAX44248 36V, Precision, Low-Power, 90µA, Single/Quad/Dual Op Amps General Description

EVALUATION KIT AVAILABLE
MAX44244/MAX44245/MAX44248
36V, Precision, Low-Power, 90µA,
Single/Quad/Dual Op Amps
General Description
The MAX44244/MAX44245/MAX44248 family of parts
provide ultra-precision, low-noise, zero-drift single/quad/
dual operational amplifiers featuring very low-power
operation with a wide supply range. The devices incorporate a patented auto-zero circuit that constantly measures and compensates the input offset to eliminate drift
over time and temperature as well as the effect of 1/f
noise. These devices also feature integrated EMI filters
to reduce high-frequency signal demodulation on the
output. The op amps operate from either a single 2.7V to
36V supply or dual ±1.35V to ±18V supply. The devices
are unity-gain stable with a 1MHz gain-bandwidth product and a low 90µA supply current per amplifier.
The low offset and noise specifications and high supply
range make the devices ideal for sensor interfaces and
transmitters.
The devices are available in FMAXM, SO, SOT23, and
TSSOP packages and are specified over the -40NC to
+125NC automotive operating temperature range.
Applications
Features
S Very Low Input Voltage Offset 7.5µV (max)
S Low 30nV/NC Offset Drift (max)
S Low 90µA Quiescent Current per Amplifier
S Low Input Noise
50nV/√Hz at 1kHz
0.5µVP-P from 0.1Hz to 10Hz
S 1MHz Gain-Bandwidth Product
S EMI Suppression Circuitry
S Rail-to-Rail Output
S 2.7V to 36V Supply Range
S µMAX, SO, SOT23, TSSOP packages
Ordering Information appears at end of data sheet.
For related parts and recommended products to use with this part,
refer to www.maximintegrated.com/MAX44244.related.
Sensors Interfaces
4-20mA and 0 to10V Transmitters
PLC Analog I/O Modules
µMAX is a registered trademark of Maxim Integrated Products, Inc.
Weight Scales
Portable Medical Devices
Typical Operating Circuit
LP+
VREF
MAX6033
REF
ISIG
(4-20mA)
R1
MAX5216
DAC
R2
MAX44244
R3
RSENSE
LP-
For pricing, delivery, and ordering information, please contact Maxim Direct
at 1-888-629-4642, or visit Maxim’s website at www.maximintegrated.com.
www.BDTIC.com/maxim
19-6367; Rev 2; 9/13
MAX44244/MAX44245/MAX44248
36V, Precision, Low-Power, 90µA,
Single/Quad/Dual Op Amps
ABSOLUTE MAXIMUM RATINGS
VDD to VSS.............................................................-0.3V to +40V
Common-Mode Input Voltage.........(VSS - 0.3V) to (VDD + 0.3V)
Differential Input Voltage IN_+, IN_- .......................................6V
Continuous Input Current Into Any Pin............................ Q20mA
Output Voltage to VSS (OUT_).................– 0.3V to (VDD + 0.3V)
Output Short-Circuit Duration (OUT_)...................................... 1s
Operating Temperature Range......................... -40NC to +125NC
Storage Temperature........................................ -65NC to +150NC
Junction Temperature......................................................+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)
SO-8
Junction-to-Ambient Thermal Resistance (BJA).........132NC/W
Junction-to-Case Thermal Resistance (BJC)................38NC/W
SO-14
TSSOP
Junction-to-Ambient Thermal Resistance (BJA).........110NC/W
Junction-to-Case Thermal Resistance (BJC)................30NC/W
FMAX
Junction-to-Ambient Thermal Resistance (BJA).........120NC/W
Junction-to-Case Thermal Resistance (BJC)................37NC/W
SOT23
Junction-to-Ambient Thermal Resistance (BJA)......324.3NC/W
Junction-to-Case Thermal Resistance (BJC)................82NC/W
Junction-to-Ambient Thermal Resistance (BJA)......206.3NC/W
Junction-to-Case Thermal Resistance (BJC)................42NC/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.maximintegrated.com/thermal-tutorial.
ELECTRICAL CHARACTERISTICS
(VDD = 10V, VSS = 0V, VIN+ = VIN- = VDD/2, RL = 5kI to VDD/2, TA = -40NC to +125NC, unless otherwise noted. Typical values are
at +25NC.) (Note 2)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
36
V
POWER SUPPLY
Supply Voltage Range
Power-Supply Rejection Ratio
(Note 3)
VDD
PSRR
Quiescent Current Per Amplifier
(MAX4244 Only)
IDD
Quiescent Current Per Amplifier
(MAX44245/MAX44248 Only)
IDD
Guaranteed by PSRR
2.7
TA = +25NC, VIN+ = VIN- = VDD/2 - 1V
140
-40NC < TA < +125NC
133
TA = +25NC
148
dB
100
160
-40NC < TA < +125NC
190
TA = +25NC
90
130
-40NC < TA < +125NC
145
FA
FA
DC SPECIFICATIONS
Input Common-Mode Range
VCM
Guaranteed by CMRR test
VSS 0.05
VDD 1.5
Maxim Integrated
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V
2
MAX44244/MAX44245/MAX44248
36V, Precision, Low-Power, 90µA,
Single/Quad/Dual Op Amps
ELECTRICAL CHARACTERISTICS (continued)
(VDD = 10V, VSS = 0V, VIN+ = VIN- = VDD/2, RL = 5kI to VDD/2, TA = -40NC to +125NC, unless otherwise noted. Typical values are
at +25NC.) (Note 2)
PARAMETER
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)
SYMBOL
CMRR
VOS
MIN
TYP
TA = +25NC, VCM = VSS - 0.05V to VDD 1.5V
126
130
-40NC < TA < +125NC, VCM = VSS - 0.05V
to VDD - 1.5V
120
IB
IOS
A­VOL
TA = +25NC
2
VOUT VSS
7.5
-40NC < TA < +125NC
10
TA = +25NC
10
30
150
300
-40NC < TA < +125NC
700
TA = +25NC
300
-40NC < TA < +125NC
VSS + 0.5V P
VOUT P VDD 0.5V
600
1400
TA = +25NC
140
-40NC < TA < +125NC
135
To VDD or VSS, noncontinuous
VDD VOUT
MAX
UNITS
dB
TC VOS
Output Short-Circuit Current
Output Voltage Swing
CONDITIONS
FV
nV/NC
pA
pA
150
dB
40
mA
TA = +25NC
80
-40NC < TA < +125NC
110
TA = +25NC
50
-40NC < TA < +125NC
75
mV
AC SPECIFICATIONS
Input Voltage-Noise Density
eN
Input Voltage Noise
Input Current-Noise Density
Gain-Bandwidth Product
iN
f = 1kHz
50
nV/√Hz
0.1Hz < f < 10Hz
500
nVP-P
f = 1kHz
0.1
pA/√Hz
1
MHz
GBW
Slew Rate
SR
AV = 1V/V, VOUT = 2VP-P
0.7
V/Fs
Capacitive Loading
CL
No sustained oscillation, AV = 1V/V
400
pF
THD+N
VOUT = 2VP-P, AV = +1V/V, f = 1kHz
-100
dB
Total Harmonic Distortion Plus
Noise
EMI Rejection Ratio
EMIRR
VRF_PEAK = 100mV
f = 400MHz
75
f = 900MHz
78
f = 1800MHz
80
f = 2400MHz
90
Maxim Integrated
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dB
3
MAX44244/MAX44245/MAX44248
36V, Precision, Low-Power, 90µA,
Single/Quad/Dual Op Amps
ELECTRICAL CHARACTERISTICS
(VDD = 30V, VSS = 0V, VIN+ = VIN- = VDD/2, RL = 5kI to VDD/2, TA = -40NC to +125NC, unless otherwise noted. Typical values are
at +25NC.) (Note 2)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
100
160
UNITS
POWER SUPPLY
Quiescent Current Per Amplifier
(MAX44244 Only)
IDD
Quiescent Current Per Amplifier
(MAX44245/MAX44248 Only)
IDD
TA = +25NC
-40NC < TA < +125NC
190
TA = +25NC
90
-40NC < TA < +125NC
130
145
FA
FA
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
VSS 0.05
TA = +25NC, VCM = VSS - 0.05V to VDD 1.5V
130
-40NC < TA < +125NC, VCM = VSS - 0.05V
to VDD - 1.5V
126
IB
IOS
AVOL
VDD 1.5
140
TA = +25NC
2
7.5
-40NC < TA < +125NC
10
TA = +25NC
10
30
150
300
-40NC < TA < +125NC
700
TA = +25NC
300
-40NC < TA < +125NC
VSS + 0.5V P VOUT
P VDD - 0.5V
600
1400
TA = +25NC
146
-40NC < TA < +125NC
140
To VDD or VSS, noncontinuous
V
dB
TC VOS
Output Short-Circuit Current
Output Voltage Swing
Guaranteed by CMRR test
150
FV
nV/°C
pA
pA
dB
40
mA
VDD VOUT
TA = +25NC
200
-40NC < TA < +125NC
270
VOUT VSS
TA = +25NC
140
-40NC < TA < +125NC
220
mV
AC SPECIFICATIONS
Input Voltage-Noise Density
eN
Input Voltage Noise
Input Current-Noise Density
Gain-Bandwidth Product
iN
GBW
f = 1kHz
50
0.1Hz < f < 10Hz
500
nVP-P
f = 1kHz
0.1
pA/√Hz
1
MHz
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nV/√Hz
4
MAX44244/MAX44245/MAX44248
36V, Precision, Low-Power, 90µA,
Single/Quad/Dual Op Amps
ELECTRICAL CHARACTERISTICS (continued)
(VDD = 30V, VSS = 0V, VIN+ = VIN- = VDD/2, RL = 5kI to VDD/2, TA = -40NC to +125NC, unless otherwise noted. Typical values are
at +25NC.) (Note 2)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Slew Rate
SR
AV = 1V/V, VOUT = 2VP-P
0.7
V/Fs
Capacitive Loading
CL
No sustained oscillation, AV = 1V/V
400
pF
THD+N
VOUT = 2VP-P, AV = +1V/V, f = 1kHz
-100
dB
Total Harmonic Distortion Plus
Noise
EMI Rejection Ratio
VRF_PEAK =
100mV
EMIRR
f = 400MHz
75
f = 900MHz
78
f = 1800MHz
80
f = 2400MHz
90
dB
Note 2: All devices are 100% production tested at TA = +25NC. Temperature limits are guaranteed by design.
Note 3: Guaranteed by design.
Note 4: At IN+ and IN-. Defined as 20log (VRF_PEAK/δVOS).
Typical Operating Characteristics
(TA
= =+25°C,
otherwise
(V
10V, Vunless
VIN+ = Vnoted.)
DD
SS = 0V,
IN- = VDD/2, RL = 5kω to VDD/2. Typical values are at TA = +25°C.)
OCCURANCE (%)
30
30
25
20
15
25
20
15
10
10
0
0.5
1.0
1.5
2.0
2.5
3.0
INPUT OFFSET VOLTAGE (µV)
3.5
94
92
90
88
86
82
0
0
96
84
5
5
98
SUPPLY CURRENT (µA)
35
100
MAX44248 toc02
40
OCCURANCE (%)
35
MAX44248 toc01
45
SUPPLY CURRENT
vs. SUPPLY VOLTAGE
INPUT OFFSET VOLTAGE DRIFT
MAX44248 toc03
INPUT OFFSET VOLTAGE HISTOGRAM
4
5
6
7
8
9 10 11 12 13 14
INPUT OFFSET VOLTAGE DRIFT (nV/°C)
80
0
10
20
30
40
SUPPLY VOLTAGE (V)
Maxim Integrated
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5
MAX44244/MAX44245/MAX44248
36V, Precision, Low-Power, 90µA,
Single/Quad/Dual Op Amps
Typical Operating Characteristics (continued)
(VDD = 10V, VSS = 0V, VIN+ = VIN- = VDD/2, RL = 5kω to VDD/2. Typical values are at TA = +25°C.)
INPUT OFFSET VOLTAGE
vs. COMMON-MODE VOLTAGE
94
92
90
88
86
2
OFFSET VOLTAGE (µV)
1
OFFSET VOLTAGE (µV)
96
3
MAX44248 toc05
98
SUPPLY CURRENT (µA)
2
MAX44248 toc04
100
INPUT OFFSET VOLTAGE
VS. TEMPERATURE
0
-1
-2
MAX44248 toc06
SUPPLY CURRENT
vs. TEMPERATURE
1
0
-1
-2
-3
84
-3
-4
82
-5
-4
80
0
25
50
75
100
-6
125
0
2
4
-25
140
0
25
50
75
TEMPERATURE (°C)
100
125
INPUT BIAS CURRENT
vs. TEMPERATURE
MAX44248 toc07
160
120
100
80
60
40
800
600
400
200
0
-200
20
-400
0
2
4
6
8
-50
10
-25
0
25
50
75
100
COMMON-MODE VOLTAGE (V)
TEMPERATURE (°C)
COMMON-MODE REJECTION RATIO
vs. FREQUENCY
COMMON-MODE REJECTION RATIO
vs. TEMPERATURE
-100
MAX44248 toc09
0
-20
125
MAX44248 toc10
0
-105
-110
CMRR (dB)
-40
CMRR (dB)
-50
6
INPUT BIAS CURRENT
COMMON-MODE VOLTAGE
180
INPUT BIAS CURRENT (pA)
-2
COMMON-MODE VOLTAGE (V)
TEMPERATURE (°C)
VS.
-4
MAX44248 toc08
-25
INPUT BIAS CURRENT (pA)
-50
-60
-80
-115
-120
-100
-125
-120
-130
-135
-140
10
100
1k
10k
FREQUENCY (Hz)
100k
1M
-50
-25
0
25
50
75
100
125
TEMPERATURE (°C)
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6
MAX44244/MAX44245/MAX44248
36V, Precision, Low-Power, 90µA,
Single/Quad/Dual Op Amps
Typical Operating Characteristics (continued)
(VDD = 10V, VSS = 0V, VIN+ = VIN- = VDD/2, RL = 5kω to VDD/2. Typical values are at TA = +25°C.)
OUTPUT VOLTAGE HIGH
vs. TEMPERATURE
-40
60
MAX44248 toc12
-20
70
50
-60
-80
-100
VOUT - VSS (mV)
60
VDD - VOUT (mV)
PSRR (dB)
80
MAX44248 toc11
0
OUTPUT VOLTAGE LOW
vs. TEMPERATURE
MAX44248 toc13
POWER-SUPPLY REJECTION RATIO
vs. FREQUENCY
50
40
30
-120
20
-140
10
100
10
1k
10k
100k
1M
-25
0
25
50
75
100
-50
125
-25
0
TEMPERATURE (°C)
50
75
100
125
OUTPUT VOLTAGE LOW
vs. SINK CURRENT
VOUT - VSS (mV)
100
10
1
MAX44248 toc15
1000
MAX44248 toc14
1000
25
TEMPERATURE (°C)
OUTPUT VOLTAGE HIGH
vs. SOURCE CURRENT
VDD - VOUT (mV)
20
0
-50
FREQUENCY (Hz)
100
10
1
0.1
1
10
0.1
SOURCE CURRENT (mA)
10
INPUT VOLTAGE 0.1Hz TO 10Hz NOISE
MAX44248 toc17
MAX44248 toc16
200
1
SINK CURRENT (mA)
INPUT VOLTAGE NOISE
vs. FREQUENCY
180
INPUT VOLTAGE NOISE (nV/√Hz)
30
10
0
-160
40
160
140
120
400nV/div
100
80
60
40
20
0
10
100
1k
10k
100k
1s/div
FREQUENCY (Hz)
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7
MAX44244/MAX44245/MAX44248
36V, Precision, Low-Power, 90µA,
Single/Quad/Dual Op Amps
Typical Operating Characteristics (continued)
(VDD = 10V, VSS = 0V, VIN+ = VIN- = VDD/2, RL = 5kω to VDD/2. Typical values are at TA = +25°C.)
INPUT CURRENT NOISE
vs. FREQUENCY
7
6
5
4
3
2
1
100
80
60
40
20
10
100
1k
10k
120
100
80
60
40
20
0
0
-20
-20
-40
-40
0
0.1
100k
MAX44248 toc20
120
LARGE-SIGNAL GAIN (dB)
8
140
MAX44248 toc19
INPUT-CURRENT NOISE (pA/√Hz)
9
SMALL-SIGNAL GAIN (dB)
MAX44248 toc18
10
LARGE-SIGNAL GAIN vs. FREQUENCY
SMALL-SIGNAL GAIN vs. FREQUENCY
140
1
10
100
1k
10k
100k
1M
0.1
1
10
FREQUENCY (Hz)
100
1k
10k
1M
LARGE-SIGNAL STEP RESPONSE
SMALL-SIGNAL STEP RESPONSE
MAX44248 toc22
MAX44248 toc21
VIN
100mV/div
VIN
2V/div
VOUT
50mV/div
VOUT
500mV/div
4µs/div
4µs/div
TOTAL HARMONIC DISTORTION
vs. FREQUENCY
POWER-UP TIME
MAX44248 toc23
MAX44248 toc24
0
VDD
10V/div
-20
THD (dB)
-40
VOUT
2V/div
100k
FREQUENCY (Hz)
FREQUENCY (Hz)
RLOAD = 1kI
-60
RLOAD = 600I
-80
-100
-120
RLOAD = 5kI
-140
20µs/div
10
100
1k
10k
100k
FREQUENCY (Hz)
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8
MAX44244/MAX44245/MAX44248
36V, Precision, Low-Power, 90µA,
Single/Quad/Dual Op Amps
Typical Operating Characteristics (continued)
(VDD = 10V, VSS = 0V, VIN+ = VIN- = VDD/2, RL = 5kω to VDD/2. Typical values are at TA = +25°C.)
OUTPUT STABILITY
vs. CAPACITIVE LOAD
OUTPUT STABILITY
vs. ISOLATION RESISTANCE
100
STABLE
10
MAX44248 toc26
MAX44248 toc25
UNSTABLE
1k
10k
ISOLATION RESISTANCE (I)
RESISTIVE LOAD (I)
10k
1k
STABLE
100
1
UNSTABLE
10
1
100
1000
10,000
100,000
100
1000
CAPACITIVE LOAD (pF)
100,000
OUTPUT IMPEDANCE
vs. FREQUENCY
CROSSTALK vs. FREQUENCY
MAX44248 toc27
-20
100
MAX44248 toc28
0
90
-40
OUTPUT IMPEDANCE (I)
CROSSTALK (dB)
10,000
CAPACITIVE LOAD (pF)
-60
-80
-100
80
70
60
50
40
30
20
-120
10
-140
100
1k
10k
100k
0
1M
1k
100
FREQUENCY (Hz)
10k
100k
1M
FREQUENCY (Hz)
EMIRR vs. FREQUENCY
MAX44248 toc29
120
100
EMIRR (dB)
80
60
40
20
0
10
100
1,000
10,000
FREQUENCY (MHz)
Maxim Integrated
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9
MAX44244/MAX44245/MAX44248
36V, Precision, Low-Power, 90µA,
Single/Quad/Dual Op Amps
Pin Configurations
TOP VIEW
+
OUTA 1
5
VDD
MAX44244
VSS 2
INA+ 3
4
N.C.
1
INA-
2
INA+
3
VSS
4
+
8
MAX44244
INA-
N.C.
7
VDD
6
OUTA
5
N.C.
µMAX
SOT23
OUTA
1
INA-
2
INA+
3
+
MAX44245
14
OUTD
13
IND-
12
IND+
VDD
4
11
VSS
INB+
5
10
INC+
INB-
6
9
INC-
OUTB
7
8
OUTC
+
OUTA 1
INA- 2
13 IND12 IND+
INA+ 3
MAX44245
VDD 4
INA-
1
2
+
10 INC+
INB- 6
9 INC-
OUTB 7
8 OUTC
SO-14
8
MAX44248
11 VSS
INB+ 5
TSSOP
OUTA
14 OUTD
7
VDD
OUTB
INA+
3
6
INB-
VSS
4
5
INB+
OUTA
1
INA-
2
INA+
3
VSS
4
+
8
MAX44248
VDD
7
OUTB
6
INB-
5
INB+
µMAX
SO-8
Maxim Integrated
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10
MAX44244/MAX44245/MAX44248
36V, Precision, Low-Power, 90µA,
Single/Quad/Dual Op Amps
Pin Description
PIN
MAX44244
MAX44245
MAX44248
NAME
FUNCTION
SOT23
µMAX
SO-14
TSSOP
SO-8
µMAX
1
6
1
1
1
1
2
4
11
11
4
4
VSS
Negative Supply Voltage
3
3
3
3
3
3
INA+
Channel A Positive Input
OUTA
Channel A Output
4
2
2
2
2
2
INA-
Channel A Negative Input
5
7
4
4
8
8
VDD
Positive Supply Voltage
—
—
5
5
5
5
INB+
Channel B Positive Input
—
—
6
6
6
6
INB-
—
—
7
7
7
7
OUTB
Channel B Output
Channel B Negative Input
Channel C Output
—
—
8
8
—
—
OUTC
—
—
9
9
—
—
INC-
Channel C Negative Input
—
—
10
10
—
—
INC+
Channel C Positive Input
—
—
12
12
—
—
IND+
Channel D Positive Input
—
—
13
13
—
—
IND-
Channel D Negative Input
—
—
14
14
—
—
OUTD
—
1, 5, 8
—
—
—
—
N.C.
Channel D Output
No Connection. Not internally
connected.
Detailed Description
Applications Information
The MAX44244/MAX44245/MAX44248 are high-precision
amplifiers with less than 2FV (typ) input-referred
offset and low input voltage-noise density at 10Hz.
1/f noise, in fact, is eliminated to improve the performance
in low-frequency applications. These characteristics are
achieved through an auto-zeroing technique that cancels
the input offset voltage and 1/f noise of the amplifier.
The devices feature ultra-high precision operational
amplifiers with a high supply voltage range designed
for load cell, medical instrumentation, and precision
instrument applications.
External Noise Suppression in EMI Form
These devices have input EMI filters to prevent effects
of radio frequency interference on the output. The EMI
filters comprise passive devices that present significant
higher impedance to higher frequency signals. See the
EMIRR vs. Frequency graph in the Typical Operating
Characteristics section for details.
High Supply Voltage Range
The devices feature 90µA current consumption per channel and a voltage supply range from either 2.7V to 36V
single supply or ±1.35V to ±18V split supply.
4–20mA Current-Loop Communication
Industrial environments typically have a large amount of
broadcast electromagnetic interference (EMI) from highvoltage transients and switching motors. This combined
with long cables for sensor communication leads to
high-voltage noise on communication lines. Current-Loop
communication is resistant to this noise because the EMI
induced current is low. This configuration also allows for
low-power sensor applications to be powered from the
communication lines.
The Typical Operating Circuit shows how the device can
be used to make a current loop driver.
The circuit uses low-power components such as the
MAX44244 op amp, the 16-bit MAX5216 DAC, and the
high-precision 60µA-only MAX6033 reference. In this
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MAX44244/MAX44245/MAX44248
36V, Precision, Low-Power, 90µA,
Single/Quad/Dual Op Amps
circuit, both the DAC and the reference are referred to
the local ground. The MAX44244 op-amp inputs are
capable of swinging to the negative supply (which is the
local ground in this case). R3 acts as a current mirror with
RSENSE. Therefore, if RSENSE = 50Ω (i.e. 20mA will drop
1V) and if the current through R3 is 10μA when IOUT is
20mA (0.05% error) then R3 = 100kΩ. R1 is chosen along
with the reference voltage to provide the 4mA offset. R2
= 512kΩ for 20mA full scale or R2 = 614kΩ for 20% overrange. RSENSE is ratiometric with R3, R1 independently
sets the offset current and R2 independently sets the
DAC scaling.
Driving High-Performance ADCs
The MAX44244/MAX44245/MAX44248’s low input offset
voltage and low noise make these amplifiers ideal for
ADC buffering. Weight scale applications require a lownoise, precision amplifier in front of an ADC. Figure 1
details an example of a load cell and amplifier driven
from the same 5V supply, along with a 16-bit delta sigma
ADC such as the MAX11205.
The MAX11205 is an ultra-low-power (< 300FA, max
active current), high-resolution, serial output ADC. It
provides the highest resolution per unit power in the
industry and is optimized for applications that require
very high dynamic range with low power such as sensors
on a 4–20mA industrial control loop. The devices provide
a high-accuracy internal oscillator that requires no
external components.
Layout Guidelines
The MAX44244/MAX44245/MAX44248 feature ultra-low
input offset voltage and noise. Therefore, to get optimum
performance follow the layout guidelines.
Avoid temperature tradients at the junction of two
dissimilar metals. The most common dissimilar metals
used on a PCB are solder-to-component lead and
solder-to-board trace. Dissimilar metals create a local
thermocouple. A variation in temperature across the
board can cause an additional offset due to Seebeck
effect at the solder junctions. To minimize the Seebeck
effect, place the amplifier away from potential heat
sources on the board, if possible. Orient the resistors
such that both the ends are heated equally. It is a good
practice to match the input signal path to ensure that the
type and number of thermoelectric juntions remain the
same. For example, consider using dummy 0ω resistors
oriented in such a way that the thermoelectric source, due
to the real resistors in the signal path, are cancelled. It is
recommended to flood the PCB with ground plane. The
ground plane ensures that heat is distributed uniformly
reducing the potential offset voltage degradation due to
Seebeck effect.
5V
5V
½ MAX44248
AMP A
VDD
5V
RF
VIN+
RG
VDD
MAX11205
RF
VIN-
OUTPUT
MICRO
CONTROLLER
VSS
AMP B
½ MAX44248
Figure 1. Weight Application
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MAX44244/MAX44245/MAX44248
36V, Precision, Low-Power, 90µA,
Single/Quad/Dual Op Amps
Chip Information
Package Information
Ordering Information
For the latest package outline information and land patterns (footprints), go to www.maximintegrated.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.
PROCESS: BiCMOS
PART
TEMP RANGE
PINPACKAGE
TOP
MARK
PACKAGE
TYPE
PACKAGE
CODE
OUTLINE
NO.
LAND PATTERN NO.
5 SOT23
U5+1
21-0057
90-0174
MAX44244AUK+
-40°C to +125°C
5 SOT23
AFMR
MAX44244AUA+
-40°C to +125°C
8 µMAX
—
8 SO
S8+4
21-0041
90-0096
MAX44245ASD+
-40°C to +125°C
14 SO
—
8 µMAX
U8+1
21-0036
90-0092
MAX44245AUD+
-40°C to +125°C
14 TSSOP
—
14 SO
S14M+4
21-0041
90-0112
MAX44248AUA+
-40°C to +125°C
8 µMAX
—
14 TSSOP
U14M-1
21-0066
90-0113
8 SO
—
MAX44248ASA+
-40°C to +125°C
+Denotes a lead(Pb)-free/RoHS-compliant package.
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MAX44244/MAX44245/MAX44248
36V, Precision, Low-Power, 90µA,
Single/Quad/Dual Op Amps
Revision History
REVISION
NUMBER
REVISION
DATE
0
7/12
Initial release
1
6/13
Added the MAX44244/MAX44245 to data sheet. Updated the Electrical
Characteristics, Absolute Maximum Ratings, Pin Description, and Pin
Configurations.
2
9/13
Released the MAX44244 for introduction. Revised the Electrical
Characteristics
DESCRIPTION
PAGES
CHANGED
—
1–13
2–5, 13
Maxim Integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim Integrated product. No circuit patent
licenses are implied. Maxim Integrated 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.
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© 2013
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