Download MAX44242 20V, Low Input Bias-Current, Low

EVALUATION KIT AVAILABLE
MAX44242
20V, Low Input Bias-Current,
Low-Noise, Dual Op Amplifier
General Description
Benefits and Features
The MAX44242 provides a combination of high voltage,
low noise, low input bias current in a dual channel and
features rail-to-rail at the output.
●● 2.7V to 20V Single Supply or ±1.35V to ±10V Dual
Supplies
●● 0.5pA (max) Input Bias Current
This dual amplifier operates over a wide supply voltage
range from a single 2.7V to 20V supply or split ±1.35V
to ±10V supplies and consumes only 1.2mA quiescent
supply current per channel.
●● 5nV/√Hz Input Voltage Noise
●● 10MHz Bandwidth
●● 8V/µs Slew Rate
●● Rail-to-Rail Output
The MAX44242 is a unity-gain stable amplifier with a
gain-bandwidth product of 10MHz. The device outputs
drive up to 200pF load capacitor without any external
isolation resistor compensation.
The MAX44242 is available in 8-pin SOT23 and µMAXM
packages and is rated for operation over the -40ºC to
+125ºC automotive temperature range.
●● Integrated EMI Filters
●● 1.2mA Supply Current per Amplifier
Ordering Information appears at end of data sheet.
Applications
●●
●●
●●
●●
●●
Chemical Sensor Interface
Photodiode Sensor Interface
Medical Pulse Oximetry
Industrial: Process and Control
Precision Instrumentation
µMAX is a registered trademark of Maxim Integrated Products, Inc.
Typical Application Circuit
VDD
MAX44242
PHOTODIODE
INPHOTODIODE
IN-
IN+
REF
IN+
REF
SENSOR PRE-AMP CONFIGURATION
19-6827 Rev 1; 11/15
MAX44242
20V, Low Input Bias-Current,
Low-Noise, Dual Op Amplifier
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 VDD or VSS....................................... 1s
Continuous Input Current (Any Pins)................................±20mA
Differential Input Voltage....................................................... ±6V
Continuous Power Dissipation (TA = +70°C)
8-Pin SOT23 (derate 5.1mW/°C above +70°C)........408.2mW
8-Pin µMAX (derate 4.5mW/°C above +70°C).............362mW
Operating Temperature Range.......................... -40°C to +125°C
Junction Temperature.......................................................+150°C
Storage Temperature Range............................. -65°C to +150°C
Lead Temperature (soldering, 10s).................................. +300°C
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
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 = 10kΩ 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
20
V
POWER SUPPLY
Supply Voltage Range
Power-Supply Rejection Ratio
VDD
PSRR
Quiescent Current Per Amplifier
IDD
Power-Up Time
tON
Guaranteed by PSRR
VDD = 2.7V to 20V,
VCM = 0V
RLOAD = infinity
2.7
TA = +25ºC
106
-40ºC ≤ TA ≤ +125ºC
100
TA = +25ºC
130
1.2
-40ºC ≤ TA ≤ +125ºC
dB
1.6
1.8
20
mA
µs
DC CHARACTERISTICS
Input Common-Mode Range
Common-Mode Rejection Ratio
Input Offset Voltage
Input Offset Voltage Drift (Note 3)
VCM
CMRR
VOS
Guaranteed by CMRR test
VCM = VSS - 0.05V
to VDD - 1.5V
TA = +25ºC
TC VOS
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IB
TA = +25ºC
94
-40ºC ≤ TA ≤ +125ºC
90
VDD - 1.5
111
50
-40ºC ≤ TA ≤ +125ºC
TA = +25ºC
Input Bias Current (Note 3)
VSS - 0.05
V
dB
600
800
0.25
2.5
0.02
0.5
-40ºC ≤ TA ≤ +85ºC
10
-40ºC ≤ TA ≤ +125ºC
50
µV
µV/ºC
pA
Maxim Integrated │ 2
MAX44242
20V, Low Input Bias-Current,
Low-Noise, Dual Op Amplifier
Electrical Characteristics (continued)
(VDD = 10V, VSS = 0V, VIN+ = VIN- = VDD/2, RL = 10kΩ 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
TA = +25°C
Input Offset Current (Note 3)
IOS
Open Loop Gain
AVOL
Input Resistance
RIN
Output Short-Circuit Current
TYP
MAX
0.04
0.5
-40°C ≤ TA ≤ +85°C
10
-40°C ≤ TA ≤ +125°C
25
250mV ≤ VOUT ≤
VDD - 250mV
TA = +25°C
134
-40°C ≤ TA ≤ +125°C
129
145
Differential
50
Common mode
200
To VDD or VSS
Output Voltage Low
VOL
VOUT - VSS
Output Voltage High
VOH
VDD - VOUT
Noncontinuous
UNITS
pA
dB
MΩ
95
mA
RLOAD = 10kΩ to VDD/2
25
RLOAD = 2kΩ to VDD/2
85
RLOAD = 10kΩ to VDD/2
37
RLOAD = 2kΩ to VDD/2
135
mV
mV
AC CHARACTERISTICS
Input Voltage-Noise Density
en
Input Voltage Noise
Input Current-Noise Density
Input Capacitance
Gain-Bandwidth Product
IN
f = 1kHz
5
nV/√Hz
0.1Hz ≤ f ≤ 10Hz
1.6
µVP-P
f = 1kHz
0.3
pA/√Hz
CIN
4
pF
GBW
10
MHz
Phase Margin
PM
CLOAD = 20pF
60
deg
Slew Rate
SR
AV = 1V/V, VOUT = 2VP-P, 10% to 90%
8
V/µs
200
pF
Capacitive Loading
CLOAD
No sustained oscillation, AV = 1V/V
Total Harmonic Distortion Plus
Noise
THD+N
VOUT = 2VP-P,
AV = +1V/V
EMI Rejection Ratio
Settling Time
EMIRR
VRF_PEAK = 100mV
f = 1kHz
-124
f = 20kHz
-100
f = 400MHz
35
f = 900MHz
40
f = 1800MHz
50
f = 2400MHz
57
To 0.01%, VOUT = 2V step, AV = -1V/V
dB
dB
1
µs
Note 2: All devices are production tested at TA = +25°C. Specifications over temperature are guaranteed by design.
Note 3: Guaranteed by design.
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Maxim Integrated │ 3
MAX44242
20V, Low Input Bias-Current,
Low-Noise, Dual Op Amplifier
Typical Operating Characteristics
(VDD = 10V, VSS = 0V, outputs have RL = 10kΩ to VDD/2. TA = +25°C, unless otherwise specified.)
toc01
toc02
25
HISTOGRAM
toc03
HISTOGRAM
SUPPLY CURRENT PER AMPLIFIER (μA)
16
20
OCCURRENCE N (%)
OCCURRENCE N (%)
14
12
10
8
6
15
10
4
5
2
toc04
VIN = VDD/2
10kΩ
-20
TA = +125°C
TA = +25°C
-60
-80
-100
-140
-1
1
3
5
7
TA = +105°C
0
-50
-100
9
TA = +25°C
0
2
TA = +85°C
4
6
8
-25
0
50
75
100
150
125
toc06
120
100
80
60
40
20
0
-50
-25
INPUT COMMON-MODE VOLTAGE (V)
0
25
50
75
100
125
TEMPERATURE (°C)
AC CMRR
vs. FREQUENCY
toc07
150
25
140
10
POWER-SUPPLY REJECTION RATIO
vs. TEMPERATURE
toc08
140
130
120
110
100
AC CMRR (dB)
POWER-SUPPLY REJECTION RATIO (dB)
-50
COMMON-MODE REJECTION RATIO
vs. TEMPERATURE
100
INPUT COMMON-MODE VOLTAGE (V)
90
70
80
60
40
50
30
VDD = 2.7V
1000
TEMPERATURE (°C)
150
50
VDD = 5.5V
1100
900
TA = +125°C
200
TA = -40°C
-120
VDD = 10V
toc05
250
TA = +85°C
-40
1200
600
300
INPUT BIAS CURRENT (pA)
0
-600 -400 -200
0
200
400
INPUT OFFSET VOLTAGE DRIFT (nV/°C)
VDD = 20V
VDD = 15V
INPUT BIAS CURRENT
vs. INPUT COMMON-MODE VOLTAGE
vs. TEMPERATURE
INPUT OFFSET VOLTAGE
vs. INPUT COMMON-MODE VOLTAGE
vs. TEMPERATURE
20
INPUT OFFSET VOLTAGE (μV)
0
-250 -200 -150 -100 -50 0 50 100 150 200 250
INPUT OFFSET VOLTAGE (μV)
VIN = VDD/2
NO LOAD
1300
COMMON-MODE REJECTION RATIO (dB)
0
SUPPLY CURRENT PER AMPLIFIER
vs. TEMPERATURE
INPUT OFFSET VOLTAGE DRIFT HISTOGRAM
INPUT OFFSET VOLTAGE HISTOGRAM
20
-50
-25
0
25
50
75
TEMPERATURE (°C)
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100
125
0
1
100
10000
1000000
FREQUENCY (Hz)
Maxim Integrated │ 4
MAX44242
20V, Low Input Bias-Current,
Low-Noise, Dual Op Amplifier
Typical Operating Characteristics (continued)
(VDD = 10V, VSS = 0V, outputs have RL = 10kΩ to VDD/2. TA = +25°C, unless otherwise specified.)
AC PSRR
vs. FREQUENCY
120
AVOL
vs. FREQUENCY
toc09
SMALL-SIGNAL RESPONSE (dB)
110
AVOL (dB)
90
80
60
70
50
30
10
40
-10
20
10
1,000
100,000
-30
10,000,000
10
1,000
FREQUENCY (Hz)
-5
-10
-15
-20
-25
2VP-P Input
10
1,000
100,000
1,000
100,000
10,000,000
0.1 Hz to 10 Hz PEAK TO PEAK NOISE
toc14
25
VINSIDE
1μV/div
20
VBACKUP
15
10
5
0
en = 1.6μVP-P
10
100
1000
10000
100000
OUTPUT VOLTAGE HIGH (VDD - VOUT)
vs. OUTPUT SOURCE CURRENT
toc15
OUTPUT SWING HIGH (mV)
INPUT CURRENT-NOISE DENSITY (pA/√Hz)
10
VOUTN
4
3
2
1
1000
FREQUENCY (Hz)
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100mVP-P
INPUT
FREQUENCY (Hz)
5
100
-15
toc13
30
10,000,000
INPUT CURRENT-NOISE DENSITY
vs. FREQUENCY
10
-10
35
FREQUENCY (Hz)
0
-5
FREQUENCY (Hz)
INPUT VOLTAGE-NOISE DENSITY
vs. FREQUENCY
40
INPUT VOLTAGE-NOISE DENSITY (nV/√Hz)
LARGE-SIGNAL RESPONSE (dB)
toc12
0
-30
0
-20
10,000,000
toc11
5
FREQUENCY (Hz)
LARGE-SIGNAL RESPONSE
vs. FREQUENCY
5
100,000
SMALL-SIGNAL RESPONSE
vs. FREQUENCY
10
130
100
AC PSRR (dB)
toc10
10000
650
600
550
500
450
400
350
300
250
200
150
100
50
0
toc16
0
4
8
12
16
20
OUTPUT SOURCE CURRENT (mA)
Maxim Integrated │ 5
MAX44242
20V, Low Input Bias-Current,
Low-Noise, Dual Op Amplifier
Typical Operating Characteristics (continued)
(VDD = 10V, VSS = 0V, outputs have RL = 10kΩ to VDD/2. TA = +25°C, unless otherwise specified.)
OUTPUT VOLTAGE SWING HIGH
vs. TEMPERATURE
OUTPUT VOLTAGE LOW (VOUT)
vs. OUTPUT SINK CURRENT
toc17
600
120
OUTPUT VOLTAGE SWING HIGH (mV)
OUTPUT SWING LOW (mV)
450
400
350
300
250
200
150
100
50
0
0
5
10
15
20
25
100
RL = 2kΩ
80
60
RL = 10kΩ
40
20
0
30
-50
-20
10
40
70
70
OUTPUT VOLTAGE SWING LOW VOL (mV)
550
500
OUTPUT VOLTAGE SWING LOW
vs. TEMPERATURE
toc18
100
60
RL = 2kΩ
50
40
30
RL = 10kΩ
20
10
0
130
-50
-20
TEMPERATURE (°C)
OUTPUT SINK CURRENT (mA)
SMALL-SIGNAL RESPONSE
vs. TIME
10
40
70
VINSIDE
LARGE-SIGNAL RESPONSE
vs. TIME
toc20
toc21
VIN
VOUTN
50mV/div
VINSIDE
VIN
1V/div
VBACKUP
VOUT
VOUT
1V/div
50mV/div
1μs/div
100nF
1μs/div
100
toc22
RESISTIVE LOAD (kΩ)
10
UNSTABLE
1
0.1
STABLE
100
1000
10000
CAPACITIVE LOAD (pF)
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100000
STABILITY
vs. CAPACITIVE LOAD AND
ISOLATION RESISTOR
100
ISOLATION RESISTANCE RISO (Ω)
STABILITY
vs. CAPACITIVE LOAD AND
RESISTIVE LOAD
0.001
130
No LOAD
VBACKUP
0.01
100
TEMPERATURE (°C)
No LOAD
VOUTN
toc19
toc23
10
UNSTABLE
1
0.1
0.01
STABLE
100
1000
10000
100000
CAPACITIVE LOAD (pF)
Maxim Integrated │ 6
MAX44242
20V, Low Input Bias-Current,
Low-Noise, Dual Op Amplifier
Typical Operating Characteristics (continued)
(VDD = 10V, VSS = 0V, outputs have RL = 10kΩ to VDD/2. TA = +25°C, unless otherwise specified.)
TOTAL HARMONIC DISTORTION
vs. INPUT FREQUENCY
vs. AMPLITUDE
toc26
TOTAL HARMONIC DISTORTION
vs. FREQUENCY
toc25
-10
-20
-30
-40
-50
-60
-70
-80
RLOAD = 600Ω RLOAD = 1kΩ
-90
RLOAD = 10kΩ
-100
-110
-120
0
2VP-P INPUT
10
100
1000
10000
TOTAL HARMONIC DISTORTION (dB)
TOTAL HARMONIC DISTORTION (dB)
0
-40
1kHz INPUT
FREQUENCY
-60
-80
20kHz INPUT
FREQUENCY
-100
-120
100000
RLOAD = 10kΩ
-20
0
FREQUENCY (Hz)
CROSSTALK
vs. FREQUENCY
0
toc27
6
8
-40
-60
-80
EMIRR
vs. FREQUENCY
100
EMI REJECTION RATIO (dB)
CROSSTALK (dB)
4
10
FREQUENCY (Hz)
-20
toc29
80
60
40
20
-100
-120
2
1
10
100
1000
10000 100000 1000000
FREQUENCY (Hz)
www.maximintegrated.com
0
10
100
1000
10000
FREQUENCY (MHz)
Maxim Integrated │ 7
MAX44242
20V, Low Input Bias-Current,
Low-Noise, Dual Op Amplifier
Pin Configuration
TOP VIEW
OUTA 1
+
MAX44242
8 VDD
INA- 2
7 OUTB
INA+ 3
6 INB-
VSS 4
5 INB+
8µMAX/SOT-23
Pin Description
PIN
NAME
FUNCTION
1
OUTA
2
INA-
Channel A Negative Input
3
INA+
Channel A Positive Input
4
VSS
Negative Supply Voltage. Connect VSS to ground if single supply is used.
5
INB+
Channel B Positive Input
6
INB-
Channel B Negative Input
7
OUTB
8
VDD
Channel A Output
Channel B Output
Positive Supply Voltage
Detailed Description
Integrated EMI Filter
Input Bias Current
The MAX44242 has an input EMI filter to avoid the output
from getting affected by radio frequency interference. The
EMI filter, composed of passive devices, presents significant higher impedance to higher frequencies.
Combining high input impedance, low input bias current,
wide bandwidth, and fast settling time, the MAX44242 is
an ideal amplifier for driving precision analog-to-digital
inputs and buffering digital-to-analog converter outputs.
The MAX44242 features a high-impedance CMOS input
stage and a special ESD structure that allows low input
bias current operation at low-input, common-mode voltages. Low input bias current is useful when interfacing
with high-ohmic or capacitive sensors and is beneficial for
designing transimpedance amplifiers for photodiode sensors. This makes the device ideal for ground-referenced
medical and industrial sensor applications.
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Electromagnetic interference (EMI) noise occurs at higher
frequency that results in malfunction or degradation of
electrical equipment.
High Supply Voltage Range
The device features 1.2mA current consumption per
channel and a voltage supply range from either 2.7V to
20V single supply or ±1.35V to ±10V split supply.
Maxim Integrated │ 8
MAX44242
20V, Low Input Bias-Current,
Low-Noise, Dual Op Amplifier
Typical Application Circuit
High-Impedance Sensor Application
High impedance sources like pH sensor, photodiodes in
applications require negligible input leakage currents to
the input transimpedance/buffer structure. The MAX44242
benefits with clean and precise signal conditioning due to
its input structure.
The device interfaces to both current-output sensors
(photodiodes) (Figure 1), and high-impedance voltage
sources (piezoelectric sensors). For current output sensors, a transimpedance amplifier is the most noise-efficient method for converting the input signal to a voltage.
High-value feedback resistors are commonly chosen to
create large gains, while feedback capacitors help stabilize the amplifier by cancelling any poles introduced in the
feedback loop by the highly capacitive sensor or cabling.
A combination of low-current noise and low-voltage noise
is important for these applications. Take care to calibrate
out photodiode dark current if DC accuracy is important.
The high bandwidth and slew rate also allow AC signal
processing in certain medical photodiode sensor applications such as pulse-oximetry. For voltage-output sensors,
a noninverting amplifier is typically used to buffer and/or
apply a small gain to the input voltage signal. Due to the
extremely high impedance of the sensor output, a low
input bias current with minimal temperature variation is
very important for these applications.
Transimpedance Amplifier
As shown in Figure 2, the noninverting pin is biased at 2V
with C2 added to bypass high-frequency noise. This bias
voltage to reverse biases the photodiode D1 at 2V which
is often enough to minimize the capacitance across the
junction. Hence, the reverse current (I ) produced by the
R
photodiode as light photons are incident on it, a proportional voltage is produced at the output of the amplifier by
the given relation:
VOUT
= IR × R1
The addition of C1 is to compensate for the instability
caused due to the additional capacitance at the input
(junction capacitance Cj and input capacitance of the op
amp CIN), which results in loss of phase margin. More
information about stabilizing the transimpedance amplifier
can be found in Application Note 5129: Stabilize Your
Transimpedance Amplifier.
C1
15nF
R1
100kΩ
+5V
MAX44242
5V
D1
R2
30kΩ
R3
20kΩ
C2
10nF
Figure 1. High-Impedance Source/Sensor Preamp Application
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Maxim Integrated │ 9
MAX44242
20V, Low Input Bias-Current,
Low-Noise, Dual Op Amplifier
Package Information
Ordering Information
PART
TEMP RANGE
PINPACKAGE
TOP
MARK
MAX44242AKA+
-40ºC to +125ºC
8 SOT23
AETK
MAX44242AUA+
-40ºC to +125ºC
8 µMAX
—
+Denotes lead(Pb)-free/RoHS-compliant package.
Chip 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.
PACKAGE
TYPE
PACKAGE
CODE
OUTLINE
NO.
LAND
PATTERN NO.
8 SOT23
K8+5
21-0078
90-0176
8 µMAX
U8+1
21-0036
90-0092
PROCESS: BiCMOS
www.maximintegrated.com
Maxim Integrated │ 10
MAX44242
20V, Low Input Bias-Current,
Low-Noise, Dual Op Amplifier
Revision History
REVISION
NUMBER
REVISION
DATE
0
12/13
Initial release
—
1
11/15
Updated Pin Configuration diagram
8
DESCRIPTION
PAGES
CHANGED
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim Integrated’s website at www.maximintegrated.com.
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.
Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc.
© 2015 Maxim Integrated Products, Inc. │ 11