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MAX40242
20V, Low Input Bias-Current,
Low-Noise, Dual Op Amp
General Description
The MAX40242 provides a combination of high voltage,
low noise, low input bias current in a dual channel and
features rail-to-rail at the output.
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.
The MAX40242 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 MAX40242 is available in 8-thin wafer-level
packages (WLPs) and is rated for operation over the
-40°C to +125°C automotive temperature range.
●● 2.7V to 20V Single Supply or ±1.35V to ±10V Dual
Supplies
●● 2pA (Max) Input Bias Current
●● 5nV/√Hz Input Voltage Noise
●● 10MHz Bandwidth
●● 8V/µs Slew Rate
●● Rail-to-Rail Output
●● Integrated EMI Filters
●● 1.2mA Supply Current per Amplifier
●● Tiny, 0.85mm x 1.65mm 8-WLP
Ordering Information appears at end of data sheet.
Applications
●●
●●
●●
●●
●●
Benefits and Features
Chemical Sensor Interface
Photodiode Sensor Interface
Medical Pulse Oximetry
Industrial: Process and Control
Precision Instrumentation
Typical Application Circuit
VDD
PHOTODIODE
INPHOTODIODE
OUT
IN-
IN+
OUT
REF
IN+
MAX40242
19-100357 Rev 0; 6/18
REF
MAX40242
20V, Low Input Bias-Current,
Low-Noise, Dual Op Amp
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-THIN WLP (derate 11.4mW/°C above +70°C)..........912mW
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)
8-THIN WLP
Junction-to-Ambient Thermal Resistance (θJA)......87.71°C/W
Junction-to-Case Thermal Resistance (θJC)...............NA°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
Guaranteed by PSRR
2.7
VDD = 2.7V to 20V, TA = +25ºC
VCM = 0V
-40ºC ≤ TA ≤ +125ºC
106
TA = +25ºC
Quiescent Current Per Amplifier
IDD
RLOAD = infinity
Power-Up Time
tON
RLOAD = 10kΩ to VDD/2, CLOAD = 20pF,
VOUT reaches VDD/2 to 1%
VCM
Guaranteed by CMRR test
130
dB
100
1.2
-40ºC ≤ TA ≤ +125ºC
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)
CMRR
VOS
VCM = VSS - 0.05V TA = +25ºC
to VDD - 1.5V
-40ºC ≤ TA ≤ +125ºC
TA = +25ºC
TC VOS
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IB
94
VDD - 1.5
111
50
V
dB
90
-40ºC ≤ TA ≤ +125ºC
TA = +25ºC
Input Bias Current (Note 3)
VSS - 0.05
600
800
0.25
2.5
0.02
2
-40ºC ≤ TA ≤ +85ºC
15
-40ºC ≤ TA ≤ +125ºC
75
µV
µV/ºC
pA
Maxim Integrated │ 2
MAX40242
20V, Low Input Bias-Current,
Low-Noise, Dual Op Amp
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 (Note 3)
Output Voltage Low
VOH
0.04
1
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
Noncontinuous (1s)
95
VOUT - VSS, RLOAD = 10KΩ to VDD/2,
TA = +25°C
11
VOUT - VSS, RLOAD = 10KΩ to VDD/2,
-40°C < TA < 125°C
VOUT - VSS, RLOAD = 2KΩ to VDD/2,
TA = +25°C
VOUT - VSS, RLOAD = 2KΩ to VDD/2,
-40°C < TA < 125°C
VOUT - VSS, RLOAD = 10KΩ to VDD/2,
TA = +25°C
Output Voltage High
MAX
-40°C ≤ TA ≤ +85°C
To VDD or VSS
VOL
TYP
MΩ
mA
15
mV
60
85
20
VOUT - VSS, RLOAD = 10KΩ to VDD/2,
-40°C < TA < 125°C
VOUT - VSS, RLOAD = 2KΩ to VDD/2,
TA = +25°C
pA
dB
25
47
UNITS
26
37
mV
80
VOUT - VSS, RLOAD = 2KΩ to VDD/2,
-40°C < TA < 125°C
100
135
AC CHARACTERISTICS
Input Voltage-Noise Density
en
Input Voltage Noise
Input Current-Noise Density
Input Capacitance
Gain-Bandwidth Product
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
IN
Phase Margin
PM
CLOAD = 20pF
60
°
Slew Rate
SR
AV = 1V/V, VOUT = 2VP-P, 10% to 90%
8
V/µs
BW
RLOAD = 10KΩ to VDD/2, CLOAD = 20pF,
AV = 1V/V
1
MHz
No sustained oscillation, AV = 1V/V
200
pF
RLOAD = 2KΩ to VDD/2, CLOAD = 20pF,
VOUT = 5VP-P, f = 100kHz
-98
dB
Large-Signal Bandwidth
Capacitive Loading
Crosstalk
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CLOAD
XT
Maxim Integrated │ 3
MAX40242
20V, Low Input Bias-Current,
Low-Noise, Dual Op Amp
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
Total Harmonic Distortion Plus Noise
EMI Rejection Ratio
Settling Time
SYMBOL
THD+N
EMIRR
CONDITIONS
VOUT = 2VP-P,
AV = +1V/V
VRF_PEAK = 100mV
MIN
TYP
f = 1kHz
-124
f = 20kHz
-100
f = 400MHz
35
f = 800MHz
40
f = 1800MHz
50
f = 2400MHz
57
To 0.1%, VOUT = 2V step, AV = -1V/V
MAX
UNITS
dB
dB
2
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 │ 4
MAX40242
20V, Low Input Bias-Current,
Low-Noise, Dual Op Amp
Typical Operating Characteristics
(VDD = 10V, VSS = 0V, outputs have RL = 10kΩ to VDD/2. TA = +25°C, unless otherwise specified.)
toc01
toc02
35
30
30
25
25
20
15
10
20
15
10
5
5
0
0
-200 -150 -100 -50
0
INPUT OFFSET VOLTAGE (μV)
INPUT OFFSET VOLTAGE
vs. INPUT COMMON-MODE VOLTAGE
vs. TEMPERATURE
10
toc04
600
TA = -40°C
-20
-30
TA = +25°C
-40
-50
TA = +85°C
-60
-70
200
VDD = 5.5V
VDD = 10V
900
VDD = 2.7V
600
300
-25
0
25
50
75
100
125
INPUT BIAS CURRENT(IB-)
vs. INPUT COMMON MODE VOLTAGE
vs. TEMPERATURE
toc05
600
TA = +125°C
400
1200
VDD = 15V
VDD = 20V
150
TEMPERATURE (°C)
INPUT BIAS CURRENT (pA)
INPUT BIAS CURRENT (pA)
-10
1500
-50
VIN = VDD/2
RLOAD = 10kΩ to VDD/2
0
INPUT OFFSET VOLTAGE (μV)
INPUT BIAS CURRENT(IB+)
vs. INPUT COMMON MODE VOLTAGE
vs. TEMPERATURE
VIN = VDD/2
NO LOAD
0
-500 -400 -300 -200 -100 0 100 200 300 400 500
INPUT OFFSET VOLTAGE DRIFT (nV/°C)
50 100 150 200
toc03
1800
HISTOGRAM
SUPPLY CURRENT PER AMPLIFIER (μA)
HISTOGRAM
OCCURRENCE N (%)
OCCURRENCE N (%)
35
SUPPLY CURRENT PER AMPLIFIER
vs. TEMPERATURE
INPUT OFFSET VOLTAGE DRIFT HISTOGRAM
INPUT OFFSET VOLTAGE HISTOGRAM
TA = +85°C
TA = 25°C
0
toc06
TA = 125°C
400
200
TA = 85°C
TA = +25°C
0
TA = +125°C
-80
-200
-90
-1
1
3
5
7
0
9
INPUT COMMON-MODE VOLTAGE (V)
2
4
6
8
0
INPUT COMMON MODE VOLTAGE VCM (V)
4
6
8
10
POWER-SUPPLY REJECTION RATIO
vs. TEMPERATURE
toc07
120
100
80
60
40
20
0
toc08
150
POWER-SUPPLY REJECTION RATIO (dB)
140
2
INPUT COMMON MODE VOLTAGE VCM (V)
COMMON-MODE REJECTION RATIO
vs. TEMPERATURE
COMMON-MODE REJECTION RATIO (dB)
-200
10
130
110
90
70
50
30
-50
-25
0
25
50
TEMPERATURE (°C)
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75
100
125
-50
-25
0
25
50
75
100
125
TEMPERATURE (°C)
Maxim Integrated │ 5
MAX40242
20V, Low Input Bias-Current,
Low-Noise, Dual Op Amp
Typical Operating Characteristics (continued)
(VDD = 10V, VSS = 0V, outputs have RL = 10kΩ to VDD/2. TA = +25°C, unless otherwise specified.)
AC COMMON MODE REJECTION RATIO
vs. FREQUENCY
AC PSRR
vs. FREQUENCY
toc09
AC POWER SUPPLY REJECTION RATIO (dB)
80
60
40
20
80
40
FREQUENCY (Hz)
FREQUENCY (Hz)
10
LARGE SIGNAL RESPONSE (dB)
0
-5
-10
VIN = 2VP-P
5
0
-5
-10
-15
-20
1E+1 1E+2 1E+3 1E+4 1E+5 1E+6 1E+7 1E+8
-20
1E+1 1E+2 1E+3 1E+4 1E+5 1E+6 1E+7 1E+8
FREQUENCY (Hz)
FREQUENCY (Hz)
VOLTS
5.E-7
0.E+0
-5.E-7
-1.E-6
-2.E-6
-2.E-6
0
4
8
12
16
4s/div
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20
24
28
32
0.01
0.1
1
10
100
-200
1000 10000 100000
Thousands
INPUT VOLTAGE-NOISE DENSITY
vs. FREQUENCY
toc14
45
40
35
30
25
20
15
10
5
0
10
100
1000
10000
100000
toc16
2
INPUT CURRENT-NOISE DENSITY (pA/√Hz)
1.E-6
-150
INPUT CURRENT-NOISE DENSITY
vs. FREQUENCY
toc15
2.E-6
-100
FREQUENCY (Hz)
INPUT VOLTAGE NOISE 0.1Hz TO 10Hz NOISE
eN = 1.61µV
2.12µVP-P
-50
GAIN
50
-15
2.E-6
0
-20
toc13
10
5
PHASE
FREQUENCY (kHz)
LARGE-SIGNAL RESPONSE
vs. FREQUENCY
VIN = 100mVP-P
50
60
0
20
1E+1 1E+2 1E+3 1E+4 1E+5 1E+6 1E+7 1E+8
toc12
100
80
20
0
1E+1 1E+2 1E+3 1E+4 1E+5 1E+6 1E+7 1E+8
SMALL-SIGNAL RESPONSE
vs. FREQUENCY
150
40
60
250
200
PHASE CURVE IS
REFERRED TO DEGREE
UNITS ON AXIS FAR RIGHT
100
100
toc11
AV = 10V/V
120
120
GAIN (dB)
100
140
INPUT VOLTAGE-NOISE DENSITY (nV/√Hz)
AC CMRR (dB)
120
SMALL SIGNAL RESPONSEL (dB)
toc10
140
140
GAIN AND PHASE
vs. FREQUENCY
(RL = 10kΩ)
1.8
1.6
1.4
1.2
1
0.8
0.6
0.4
0.2
0
10
100
1000
10000
FREQUENCY (Hz)
100000
Maxim Integrated │ 6
MAX40242
20V, Low Input Bias-Current,
Low-Noise, Dual Op Amp
Typical Operating Characteristics (continued)
(VDD = 10V, VSS = 0V, outputs have RL = 10kΩ to VDD/2. TA = +25°C, unless otherwise specified.)
1000
OUTPUT VOTLAGE LOW
vs. OUTPUT SINK CURRENT
toc17
TA = 85°C
750
TA = 125°C
500
250
TA = 25°C
TA = -40°C
0
0
4
8
OUTPUT VOLTAGE LOW VOL (VOUT - VSS) (mV)
OUTPUT VOLTAGE HIGH VOH (VDD - VOUT) (mV)
OUTPUT VOTLAGE HIGH
vs. OUTPUT SOURCE CURRENT
600
16
toc19
TA = 125°C
500
TA = 85°C
400
VIN
50mV/div
300
200
VOUT
50mV/div
100
TA = -40°C
0
12
SMALL-SIGNAL RESPONSE
vs. TIME
toc18
0
20
4
8
12
TA = 25°C
16
20
SINK CURRENT (mA)
SOURCE CURRENT (mA)
LARGE-SIGNAL RESPONSE
vs. TIME
STABILITY
vs. CAPACITIVE LOAD AND
RESISTIVE LOAD
100
toc20
toc21
VIN
1V/div
VINSIDE
VBACKUP
VOUT
1V/div
RESISTIVE LOAD (kΩ)
80
VOUTN
STABLE
60
UNSTABLE
40
20
0
10
1μs/div
STABILITY
vs. CAPACITIVE LOAD AND
ISOLATION RESISTOR
ISOLATION RESISTANCE RISO (Ω)
100
100
1000
10000
CAPACITIVE LOAD (pF)
toc22
10
UNSTABLE
1
0.1
STABLE
0.01
100
1000
10000
100000
CAPACITIVE LOAD (pF)
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Maxim Integrated │ 7
MAX40242
20V, Low Input Bias-Current,
Low-Noise, Dual Op Amp
Typical Operating Characteristics (continued)
(VDD = 10V, VSS = 0V, outputs have RL = 10kΩ to VDD/2. TA = +25°C, unless otherwise specified.)
TOTAL HARMONIC DISTORTION+NOISE
vs. INPUT FREQUENCY
vs. AMPLITUDE
toc25
toc24
0
-10
-20
-30
-40
-50
-60
-70
-80
-90
-100
-110
-120
2VP-P INPUT
10
100
1000
10000
100000
0
TOTAL HARMONIC DISTORTION + NOISE (dB)
TOTAL HARMONIC DISTORTION + NOISE (dB)
TOTAL HARMONIC DISTORTION+NOISE
vs. FREQUENCY
RLOAD = 10kΩ
-20
-40
1kHz INPUT
FREQUENCY
-60
-80
20kHz INPUT
FREQUENCY
-100
-120
0
CROSSTALK (dB)
-20
-40
-60
-80
-100
-120
1E+1 1E+2 1E+3 1E+4 1E+5 1E+6 1E+7 1E+8
FREQUENCY (Hz)
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4
6
8
EMIRR
vs. FREQUENCY
toc26
100
EMI REJECTION RATIO (dB)
0
CROSSTALK
vs. FREQUENCY
2
10
FREQUENCY (Hz)
FREQUENCY (Hz)
toc27
80
60
40
20
0
10
100
1000
10000
FREQEUNCY (MHz)
Maxim Integrated │ 8
MAX40242
20V, Low Input Bias-Current,
Low-Noise, Dual Op Amp
Pin Configuration
2
3
4
INA-
OUTA
OUTB
INB-
+
1
A
MAX40242
B
INA+
VSS
VDD
INB+
WLP
Bump Description
BUMP (WLP)
NAME
FUNCTION
A1
INA-
A2
OUTA
Channel A Negative Input
Channel A Output
A3
OUTB
Channel B Output
A4
INB-
Channel B Negative Input
B1
INA+
Channel A Positive Input
B2
VDD
Positive Supply Voltage
B3
VSS
Negative Supply Voltage. Connect VSS to ground if single supply is used.
B4
INB+
Channel B Positive Input
Detailed Description
Integrated EMI Filter
Input Bias Current
The MAX40242 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 MAX40242 is
an ideal amplifier for driving precision analog-to-digital
inputs and buffering digital-to-analog converter outputs.
The MAX40242 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 groundreferenced 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 │ 9
MAX40242
20V, Low Input Bias-Current,
Low-Noise, Dual Op Amp
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 MAX40242
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 noiseefficient 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 1, 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 (IR) produced
by the 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
MAX40242
5V
D1
R2
30kΩ
R3
20kΩ
C2
10nF
Figure 1. High-Impedance Source/Sensor Preamp Application
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Maxim Integrated │ 10
MAX40242
20V, Low Input Bias-Current,
Low-Noise, Dual Op Amp
Package Information
Ordering Information
PART
TEMP RANGE
MAX40242ANA+ -40ºC to +125ºC
PINPACKAGE
TOP
MARK
8-THIN WLP
+AAN
+Denotes lead(Pb)-free/RoHS-compliant package.
Chip Information
PROCESS: BiCMOS
www.maximintegrated.com
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-THIN WLP
N80D1+1
21-100280
Apps Note
1891
Maxim Integrated │ 11
MAX40242
20V, Low Input Bias-Current,
Low-Noise, Dual Op Amp
Revision History
REVISION
NUMBER
REVISION
DATE
0
6/18
DESCRIPTION
Initial release
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.
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