Evaluation Kit
Available
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MAX40079/MAX40087/
MAX40077/MAX40089/
MAX40078
Single/Dual/Quad Ultra-Low
Input Bias Current,
Low-Noise Amplifiers
General Description
The
MAX40079/MAX40087/MAX40077/MAX40089/
MAX40078 are wide band, low-noise, low-input bias
current operational amplifiers that offer rail-to-rail outputs
and single-supply operation from 2.7V to 5.5V. These lownoise amps draw 2.2mA of quiescent supply current per
amplifier. This family of amplifiers offers ultra-low distortion
(0.0002% THD+N), as well as low input voltage-noise
density (4.2nV/√Hz) and low input current-noise density
(0.5fA/√Hz). The low input bias current of 0.3pA (typ) and
low noise(4.5nV/√Hz), together with the wide bandwidth,
provides excellent performance for transimpedance (TIA)
and imaging applications.
These amplifiers have outputs which swing rail-to-rail and
their input common-mode voltage range includes ground.
The MAX40079/MAX40077/MAX40078 are single/dual/
quad respectively in unity-gain stable with a bandwidth
of 10MHz. The MAX40087/MAX40089 are single/dual
respectively with gain ≥ 5 stable and bandwidth of 42MHz.
They operate over the full -40°C to +125°C temperature
range.
Single channel op amps are available in 6-bump wafer-level
package (WLP) and SOT23 6-pin packages. The dual channel
op amps are available in 8-bump WLP and μMAX-8 packages.
The quad channel option is available in 14-TSSOP package.
Benefits and Features
●
●
●
●
●
●
●
●
●
●
●
●
Low Input Voltage Noise Density: 4.2nV/√Hz at 30KHz
Low Input Current Noise Density: 0.5fA/√Hz
Low Input Bias Current: 0.3pA (typ)
Low Distortion: 0.00035% or -109dB THD+N (1kΩ
Load)
Single-Supply Operation from +2.7V to +5.5V
Input Common-Mode Voltage Range Includes
Ground
Rail-to-Rail Output Swings with a 1kΩ Load
Wide Bandwidth: MAX40079/MAX40077/MAX40078
(10MHz); MAX40087/MAX40089 (42MHz)
Excellent DC Characteristics: VOS ≤ 30μV
Single-Channel 6-bump WLP in 1.31mm x 0.73mm
with 0.35mm Bump Pitch
Dual-Channel 8-bump WLP in 0.96mm x 1.66mm
with 0.35mm Bump Pitch
Available in Space-Saving 6-WLP, 6-SOT, 8-WLP
and μMAX Packages
THD+N Performance
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. FREQUENCY
Applications
-80
● pH Probes and Reference Electrodes
-90
toc20
VOUT = 4 VP-P
● Transimpedance Amplifiers
THD + N (dB)
● ADC Buffers
● DAC Output Amplifiers
● Low-Noise Microphone/Preamplifiers
● Digital Scales
-100
RL = 1KΩ
-110
● Strain Gauges/Sensor Amplifiers
RL = 10KΩ
● Medical Instrumentation
-120
Ordering Information appears at end of data sheet.
20
200
2000
20000
FREQUENCY(Hz)
19-100237; Rev 10; 10/21
© 2021 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners.
One Analog Way, Wilmington, MA 01887 U.S.A.
|
Tel: 781.329.4700
|
© 2021 Analog Devices, Inc. All rights reserved.
MAX40079/MAX40087/
MAX40077/MAX40089/
MAX40078
Single/Dual/Quad Ultra-Low
Input Bias Current,
Low-Noise Amplifiers
Absolute Maximum Ratings
Input Differential Voltage(IN+ - IN-)
MAX40079/MAX40087/MAX40077/MAX40089/MAX40078
(continuous).............................................................-3V to +3V
MAX40079/MAX40087/MAX40077/MAX40089/MAX40078
(transient, 10s).........................................................-6V to +6V
Power-Supply Voltage (VDD to VSS)........................-0.3V to +6V
Analog Input Voltage
((IN+,IN-) to VSS).............................VSS - 0.3V to VDD + 0.3V
SHDN Input Voltage (to VSS).......................... VSS - 0.3V to +6V
Continuous Input Current (IN+,IN-)...................................±20mA
Output Short-Circuit Duration to Either Supply..........Continuous
Operating Temperature Range.......................... -40°C to +125°C
Continuous Power Dissipation (TA = +70°C)
SOT23-6 (derate 8.7mW/°C above +70°C)..................696mW
6-Bump WLP (derate 10.19mW/°C above +70°C).......815mW
8-μMAX (derate 4.8mW/°C above +70°C)..............387.80mW
8-Bump WLP (derate 10.90mW/°C above +70°C).......872mW
14-TSSOP (derate 10mW/°C above +70°C)...........796.80mW
Storage Temperature Range............................. -65°C to +150°C
Lead Temperature ((soldering, 10s))................................ +300°C
Soldering Temperature (reflow)........................................+260°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 Information
6-SOT23
PACKAGE CODE
U6+1
Outline Number
21-0058
Land Pattern Number
90-0175
Thermal Resistance, Four-Layer Board:
Junction to Ambient (θJA)
115°C/W
Junction to Case (θJC)
80°C/W
6-WLP
PACKAGE CODE
N60F1+1
Outline Number
21-100174
Land Pattern Number
Refer to Application Note 1891
Thermal Resistance, Four-Layer Board:
Junction to Ambient (θJA)
98.06°C/W
Junction to Case (θJC)
N/A
8-μMAX
PACKAGE CODE
U8+1
Outline Number
21-0036
Land Pattern Number
90-0092
Thermal Resistance, Single-Layer Board:
Junction to Ambient (θJA)
221°C/W
Junction to Case (θJC)
42°C/W
Thermal Resistance, Four-Layer Board:
Junction to Ambient (θJA)
206.30°C/W
Junction to Case (θJC)
42°C/W
www.maximintegrated.com
Maxim Integrated │ 2
MAX40079/MAX40087/
MAX40077/MAX40089/
MAX40078
Single/Dual/Quad Ultra-Low
Input Bias Current,
Low-Noise Amplifiers
Package Information (continued)
8-WLP
PACKAGE CODE
N80C1+1
Outline Number
21-100236
Land Pattern Number
Refer to Application Note 1891
Thermal Resistance, Four-Layer Board:
Junction to Ambient (θJA)
91.72°C/W
Junction to Case (θJC)
N/A
14-TSSOP
PACKAGE CODE
U14M+1
Outline Number
21-0066
Land Pattern Number
90-0113
Thermal Resistance, Single-Layer Board:
Junction to Ambient (θJA)
110°C/W
Junction to Case (θJC)
30°C/W
Thermal Resistance, Four-Layer Board:
Junction to Ambient (θJA)
100.4°C/W
Junction to Case (θJC)
30°C/W
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 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.
www.maximintegrated.com
Maxim Integrated │ 3
MAX40079/MAX40087/
MAX40077/MAX40089/
MAX40078
Single/Dual/Quad Ultra-Low
Input Bias Current,
Low-Noise Amplifiers
Package Information (continued)
COMMON DIMENSIONS
Pin 1
Indicator
Marking
E
1
A
see Note 7
0.50 MAX
0.17 0.03
A
A1
0.30 REF
A2
AAAA
D
0.040 BASIC
0.22 0.03
A3
b
SIDE VIEW
TOP VIEW
0.727
1.308
D
E
A
0.35 BASIC
0.70 BASIC
D1
A3
E1
A1
A2
E1
SE
B
B
D1
A
1
2
3
A
BOTTOM VIEW
- DRAWING NOT TO SCALE -
www.maximintegrated.com
SE
0.00 BASIC
DEPOPULATED BUMPS:
NONE
NOTES:
1. Terminal pitch is defined by terminal center to center value.
2. Outer dimension is defined by center lines between scribe lines.
3. All dimensions in millimeter.
4. Marking shown is for package orientation reference only.
5. Tolerance is ± 0.02 unless specified otherwise.
6. All dimensions apply to PbFree (+) package codes only.
7. Front - side finish can be either Black or Clear.
SD
e
b
0.05 M
0.175 BASIC
SD
0.05 S
FRONT VIEW
0.35 BASIC
e
S
0.025
0.025
maxim
integrated
S AB
TITLE
TM
PACKAGE OUTLINE 6 BUMPS
THIN WLP PKG. 0.35 mm PITCH,N60F1+1
APPROVAL
DOCUMENT CONTROL NO.
21-100174
REV.
A
1
1
Maxim Integrated │ 4
MAX40079/MAX40087/
MAX40077/MAX40089/
MAX40078
Single/Dual/Quad Ultra-Low
Input Bias Current,
Low-Noise Amplifiers
Electrical Characteristics
(VDD = +5V, VSS = 0V, VCM = 2.5V, SHDN = VDD, VOUT = VDD/2, RL = 10kΩ = tied to VDD/2, TA = -40°C to +125°C, unless otherwise
noted. Typical values are at TA = +25°C. (Note 1))
PARAMETER
SYMBOL
Supply Voltage Range
VDD
Quiescent Supply Current,
per Amplifier
IDD
Power-Up Time
Shutdown Supply Current
Input Offset Voltage
Input Offset Drift
ISHDN
VOS
MIN
TYP
2.7
MAX
UNITS
5.5
V
VDD = 3.3V (TA = 25°C only)
2.2
2.9
VDD = 5V, over temperature to 125°C
2.5
3.8
VDD = 0 to 5V step, VOUT = 2.5V ±1%
13
µs
SHDN function only for Single Versions
(MAX40079/MAX40087)
0.4
µA
at 25°C
30
Over the full temperature range
350
750
µV
0.3
6
µV/°C
0.3
260
pA
Input Offset Current
(Note 2)
IOS
0.1
150
pA
Input Resistance
RIN
1000
Input Capacitance
CIN
Input Common Mode
Range
Common Mode Rejection
Ratio
VIN+, VIN-
CMRR
Over temperature, to 125°C
mA
IB
Input Bias Current (Note 2)
VOS-TC
CONDITIONS
Guaranteed by PSRR test
Either input, over entire CMIR
-0.2
Guaranteed by CMRR test, -40°C to +125°C
-0.1
VDD
- 1.5
DC, -0.2V < VIN+, VIN- < VDD - 1.5V, at 25°C
90
DC, -0.1V < VIN+, VIN- < VDD - 1.5V, -40°C to
+125°C
87
AC, 100mVPP at 10kHz, DC in 0V to VDD - 2V
range
DC, 2.7V < VDD < 5.5V
Power Supply Rejection
Ratio, AC
PSRR
AC, 100mVPP at 1MHz with VDD = 5V DC
offset
AOL
VDD-VOH
Output Voltage Swing Low
(VOL)
VOL
V
120
dB
60
90
120
dB
40
dB
RL = 10KΩ to VDD/2, VOUT = 200mV to
VDD - 250mV
90
120
RL = 1kΩ to VDD/2, VOUT = 200mV to
VDD - 250mV
85
110
RL = 50Ω to VDD/2, VOUT = 200mV to
VDD - 250mV
85
110
RL = 10KΩ to VDD/2, VDD - VOH
Output Voltage Swing High
(VOH)
pF
Guaranteed by CMRR test at 25°C
PSRR
www.maximintegrated.com
7
VDD 1.5
Power Supply Rejection
Ratio, DC
Open-Loop Gain
GΩ
dB
10
45
RL = 1KΩ to VDD/2, VDD - VOH
80
200
RL = 500Ω to VDD/2, VDD - VOH
100
300
RL = 10KΩ to VDD/2, VOL - VSS
10
40
RL = 1KΩ to VDD/2, VOL - VSS
50
150
RL = 500Ω to VDD/2, VOL - VSS
80
250
mV
mV
Maxim Integrated │ 5
MAX40079/MAX40087/
MAX40077/MAX40089/
MAX40078
Single/Dual/Quad Ultra-Low
Input Bias Current,
Low-Noise Amplifiers
Electrical Characteristics (continued)
(VDD = +5V, VSS = 0V, VCM = 2.5V, SHDN = VDD, VOUT = VDD/2, RL = 10kΩ = tied to VDD/2, TA = -40°C to +125°C, unless otherwise
noted. Typical values are at TA = +25°C. (Note 1))
PARAMETER
Short-Circuit Current
Gain Bandwidth Product
SYMBOL
ISC
GBWP
Phase Margin
Φm
Gain Margin
GM
Slew Rate
SR
Settling Time
Stable Capacitive Load
Integrated 1/f Input
Voltage Noise
CLOAD
Vn
Input Voltage Noise
Density
eN
Input Current Noise density
iN
Total Harmonic Distortion
+ Noise (AV = +1 stable)
Total Harmonic Distortion +
Noise (Min AV = +5 stable)
ElectroMagnetic
Interference Rejection
Ratio
THD+N
THD+N
EMIRR
CONDITIONS
MIN
TYP
To either VDD or VSS
50
Unity Gain, AV = +1 (MAX40079/MAX40077/
MAX40078)
10
Min Gain version, AV = +5 (MAX40087/
MAX40089)
42
Unity Gain version, AV = +1
70
Minimum Gain, AV = +5 version
80
MAX
UNITS
mA
MHz
12
°
dB
Unity Gain version, AV = +1
3
Minimum Gain, AV = +5 version
10
Unity gain version, AV = +1, to 0.01%,
VOUT = 2V step
2
Minimum gain, AV = +5, to 0.01%,
VOUT = 2V step
2
No sustained oscillation
50
pF
0.1Hz to 10Hz
1.7
µVPP
f = 10Hz
260
f = 1kHz
5.5
f = 30kHz
4.2
f = 1kHz
0.5
Unity gain, AV = +1, VOUT = 4VPP at 1kHz,
RL = 10kΩ to GND
114
Unity gain, AV = +1, VOUT = 4VPP at 20kHz,
RL = 10kΩ to GND
103
Unity gain, AV = +1, VOUT = 4VPP at 1kHz,
RL= 1kΩ to GND
114
Unity gain, AV = +1, VOUT = 4VPP at 20kHz,
RL= 1kΩ to GND
100
Unity gain, AV = +5, VOUT = 4VPP at 1kHz,
RL = 10kΩ to GND
108
Unity gain, AV = +5, VOUT = 4VPP at 20kHz,
RL = 10kΩ to GND
110
Unity gain, AV = +5, VOUT = 4VPP at 1kHz,
RL = 1kΩ to GND
106
Unity gain, AV = +5, VOUT = 4VPP at 20kHz,
RL = 1kΩ to GND
110
VRF_PP = 100mV, fIN = 2400MHz
55
V/µs
µs
nV/√Hz
fA/√Hz
dB
dB
dB
Note 1: Limits are 100% tested at TA = +25°C. Limits over the operating temperature range and relevant supply voltage range are
guaranteed by design and characterization.
Note 2: Guaranteed by design and bench characterization.
www.maximintegrated.com
Maxim Integrated │ 6
MAX40079/MAX40087/
MAX40077/MAX40089/
MAX40078
Single/Dual/Quad Ultra-Low
Input Bias Current,
Low-Noise Amplifiers
Typical Operating Characteristics
VDD = +5V, VSS = 0V, VCM = VDD/2, RL = 10kΩ to VDD/2, CL = 10pF to GND, TA = +25°C, unless otherwise noted. (TA = +25°C, unless
otherwise noted.)
6
4
2
0
10
20
30
40
50
60
70
80
90
2.5
2
1.5
1
TA = 25°C
TA = -40°C
0.5
0
100
TA = 125°C
TA = 85°C
OFFSET VOLTAGE (µV)
1.5
2
2.5
3
3.5
4
4.5
5
toc03
2.6
QUIESCENT SUPPLY CURRENT (mA)
QUIESCENT SUPPLY CURRENT (mA)
FREQUENCY (NO. OF UNITS)
8
toc02
3
toc01
0
SUPPLY CURRENT vs. TEMPERATURE
SUPPLY CURRENT vs. SUPPLY VOLTAGE
OFFSET VOLTAGE HISTOGRAM
10
2.55
2.5
2.45
2.4
2.35
5.5
VDD = 3.3V
-40 -25 -10 5
SUPPLY VOLTAGE (V)
INPUT OFFSET VOLTAGE
vs. INPUT COMMON MODE VOTLAGE
INPUT OFFSET VOLTAGE
vs. TEMPERATURE
toc04
50
20
10
0
10
-10
-20
-30
-20
-40
-40 -25 -10 5
TA = 25°C
0
-10
20 35 50 65 80 95 110 125
TA = 85°C
toc07
0.3
0.1
-0.1
-0.3
2
2.5
3
INPUT COMMON MODE VOLTAGE (V)
www.maximintegrated.com
2.9
160
-20
-25
-30
-40
3.5
-40 -25 -10 5
3.5
toc08
120
100
80
60
40
20
0
2
4
ISINK (mA)
6
8
20 35 50 65 80 95 110 125
TEMPERATURE (°C)
140
0
1.5
2.3
10
OUTPUT VOLTAGE HIGH
vs. OUTPUT SOURCE CURRENT
VDD = 5V
140
OUTPUT VOTLAGE HIGH (VDD - VOUT ) (mV)
VDD = 5.0V
OUTPUT VOTLAGE LOW (VOUT -VSS) (mV)
INPUT BIAS CURRENT (pA)
0.5
1
1.7
OUTPUT VOLTAGE LOW
vs. OUTPUT SINK CURRENT
VDD = 5V, VSS = 0V
INPUT BIAS CURRENT vs.
INPUT COMMON MODE VOLTAGE
0.5
1.1
-15
INPUT COMMON MODE VOLTAGE (V)
TEMPERATURE (°C)
0
0.5
-5
-10
-35
TA = 125°C
-0.1
VDD = 5V
0
INPUT BIAS CURRENT (pA)
INPUT OFFSET VOTLAGE (μV)
INPUT OFFSET VOLTAGE (µV)
30
toc06
5
TA = -40°C
20
40
-0.5
INPUT BIAS CURRENT
vs. TEMPERATURE
toc05
30
20 35 50 65 80 95 110 125
TEMPERATURE(°C)
toc09
120
100
80
60
40
20
0
0
2
4
6
8
10
ISOURCE (mA)
Maxim Integrated │ 7
MAX40079/MAX40087/
MAX40077/MAX40089/
MAX40078
Single/Dual/Quad Ultra-Low
Input Bias Current,
Low-Noise Amplifiers
Typical Operating Characteristics (continued)
VDD = +5V, VSS = 0V, VCM = VDD/2, RL = 10kΩ to VDD/2, CL = 10pF to GND, TA = +25°C, unless otherwise noted. (TA = +25°C, unless
otherwise noted.)
OUTPUT VOLTAGE LOW vs. TEMPERATURE
RLOAD = 10kΩ
VSUPPLY = 5V
-50
0
50
100
RLOAD = 10kΩ
VDD = 5.5V
105
VDD = 2.7V
100
VSUPPLY = 5V
-50
0
50
100
95
150
-50
0
50
100
150
TEMPERATURE (°C)
VOLTAGE NOISE DENSITY vs. FREQUENCY
INPUT VOLTAGE NOISE 0.1Hz TO 10Hz NOISE
POWER-SUPPLY REJECTION RATIO
vs. FREQUENCY
toc14
2.E-6
e N = 1.73µV
2.12µVP-P
2.E-6
100
1.E-6
90
80
5.E-7
70
60
50
0.E+0
-5.E-7
40
30
-1.E-6
20
-2.E-6
10
1
10
100
1000
10000
100000
-2.E-6
0
10
140
120
-40
100
DC CMRR (dB)
-30
-50
-60
80
40
-80
20
1
10
100
FREQUENCY(kHz)
www.maximintegrated.com
50
-40
-60
-80
-100
-120
60
0.01
0.1
1
1000 10000 100000
0
10
100
GAIN AND PHASE vs. FREQUENCY
(RL = 10kΩ, CL = 10pF)
toc17
100
90
VDD = 2.7V
toc18
toc13
AV = 1000V/V
80
70
VDD = 5.5V
GAIN
60
50
PHASE CURVE IS
REFERRED TO DEGREE
UNITS ON AXIS FAR RIGHT
-50
-100
10
-150
0
TEMPERATURE (°C)
150
0
20
20 35 50 65 80 95 110 125
200
50
PHASE
40
-10
250
100
30
-40 -25 -10 5
1000 10000 100000
FREQUENCY(kHz)
60
-70
0.1
40
COMMON MODE REJECTION RATIO
vs. TEMPERATURE
toc16
0.01
30
-20
10s/div
COMMON MODE REJECTION RATIO
vs. FREQUENCY
-20
20
toc15
0
POWER-SUPPLY REJECTION RATIO (dB)
toc13
FREQUENCY(Hz)
COMMON MODE REJECTION RATIO(dB)
110
TEMPERATURE (°C)
110
-90
VDD = 5V
115
TEMPERATURE (°C)
120
0
RLOAD = 1kΩ
10
1
150
120
RLOAD = 500Ω
OPEN-LOOP GAIN (dB)
10
toc12
125
GAIN (dB)
VOLTAGE NOISE SPECTRAL DENSITY (nV/ √Hz)
OUTPUT VOTLAGE HIGH (VDD - VOUT ) (mV)
RLOAD = 1kΩ
OPEN-LOOP GAIN vs. TEMPERATURE
toc11
100
in VOLTS
OUTPUT VOTLAGE LOW (VOUT -VSS) (mV)
RLOAD = 500Ω
1
OUTPUT VOLTAGE HIGH vs. TEMPERATURE
toc10
100
-200
0.01
0.1
1
10
100
1000 10000 100000
FREQUENCY (kHz)
Maxim Integrated │ 8
MAX40079/MAX40087/
MAX40077/MAX40089/
MAX40078
Single/Dual/Quad Ultra-Low
Input Bias Current,
Low-Noise Amplifiers
Typical Operating Characteristics (continued)
VDD = +5V, VSS = 0V, VCM = VDD/2, RL = 10kΩ to VDD/2, CL = 10pF to GND, TA = +25°C, unless otherwise noted. (TA = +25°C, unless
otherwise noted.)
GAIN AND PHASE vs. FREQUENCY
(RL = 10kΩ, CL = 10pF)
70
200
PHASE CURVE IS
REFERRED TO DEGREE
UNITS ON AXIS FAR RIGHT
50
40
50
20
0
GAIN
-50
10
RL = 1KΩ
-200
-20
-250
0.01
0.1
1
10
100
20
30
20
UNSTABLE
20000
10
100
1000
2
2.5
3
3.5
4
4.5
5
toc24
IN+
10mV/div
UNSTABLE
STABLE
1
OUTPUT
50mV/div
CAPACITIVE LOAD (pF)
LARGE-SIGNAL PULSE RESPONSE
(CL = 10pF)
1.5
AAVV=1V/V
=1V/V
AV = 5V/V
10
0.1
10000
1
SMALL-SIGNAL PULSE RESPONSE
(CLOAD= 10pF)
10
0
0.5
OUTPUT VOLTAGE SWING (VP-P)
toc23
100
RESISTIVE LOAD (kΩ)
STABLE
2000
STABILITY vs. CAPACITIVE AND RESISTIVE
LOAD IN PARALLEL WITH CL
toc22
40
200
-120
FREQUENCY(Hz)
UNDER THE CURVE AS
SHOWN IS UNSTABLE REGION
50
RL = 1kΩ
RL = 10kΩ
Thousands
ISOLATION RESISTANCE
vs. CAPACITIVE STABILITY
-100
-110
RL = 10KΩ
-120
1000 10000 100000
FREQUENCY (kHz)
60
-110
-150
-10
-90
-100
-100
AV = 5V/V or 14dB
0
fIN = 20kHz
-90
100
PHASE
30
toc21
-80
VOUT = 4 VP-P
150
THD + N (dB)
GAIN (dB)
60
ISOLATION RESISTANCE (Ω)
toc20
-80
250
THD + N (dB)
toc19
toc13
80
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. OUTPUT VOLTAGE SWING
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. FREQUENCY
100
CAPACITIVE LOAD (pF)
1µs/div
1000
CROSSTALK
vs. FREQUENCY
toc25
toc26
0
AVV=1V/V
=1V/V
= 5V/V
V=1V/V
AVAA=1V/V
-20
CROSSTALK (dB)
IN+
100mV/div
OUTPUT
500mV/div
-40
-60
-80
-100
-120
1µs/div
www.maximintegrated.com
10
100
1K
10K
100K
1M
10M
100M
FREQUENCY (Hz)
Maxim Integrated │ 9
MAX40079/MAX40087/
MAX40077/MAX40089/
MAX40078
Single/Dual/Quad Ultra-Low
Input Bias Current,
Low-Noise Amplifiers
Pin Configurations
TOP VIEW
1
VSS
2
INA+
6 VDD
MAX40079
MAX40087
+
OUTA
MAX40079/
MAX40087
TOP VIEW
+
5 SHDN
4 INA-
3
IN+
VSS
OUT
A1
A2
A3
B1
B2
B3
IN-
SHDN
VDD
6-WLP
SOT23-6
TOP VIEW
3
2
4
+
1
A
INA-
INA+
VSS
INB+
OUTA
1
INA-
2
INA+
3
VSS
4
MAX40077/MAX40089
B
OUTA
VDD
OUTB
INB-
+
MAX40077/
MAX40089
8
VDD
7
OUTB
6
INB-
5
INB+
WLP
µMAX
TOP VIEW
+
14
OUTD
13
IND-
12
IND+
11
VSS
5
10
INC+
INB-
6
9
INC-
OUTB
7
8
OUTC
OUTA
1
INA-
2
INA+
3
VDD
4
INB+
MAX40078
TSSOP
www.maximintegrated.com
Maxim Integrated │ 10
MAX40079/MAX40087/
MAX40077/MAX40089/
MAX40078
Single/Dual/Quad Ultra-Low
Input Bias Current,
Low-Noise Amplifiers
Pin Description
PIN
NAME
FUNCTION
SOT23-6
6-WLP
8-WLP
8-ΜMAX
14-TSSOP
1
A3
B1
1
1
OUTA
2
A2
A3
4
11
VSS
Negative Power Supply Input. Connect VSS to 0V
in single-supply application.
3
A1
A2
3
3
INA+
Non-Inverting Input, Channel A
4
B1
A1
2
2
INA-
Inverting Input, Channel A
5
B2
—
—
—
SHDN
6
B3
B2
8
4
VDD
Positive Power Supply Voltage Input
—
—
A4
5
5
INB+
Noninverting Input, Channel B
—
—
B4
6
6
INB-
Inverting Input, Channel B
—
—
B3
7
7
OUTB
Output, Channel B
—
—
—
—
10
INC+
Noninverting Input, Channel C
—
—
—
—
9
INC-
Inverting Input, Channel C
—
—
—
—
8
OUTC
Output, Channel C
—
—
—
—
12
IND+
Noninverting Input, Channel D
—
—
—
—
13
IND-
Inverting Input, Channel D
—
—
—
—
14
OUTD
Output, Channel A
Shutdown. Pull high for normal operation and low
for shutdown
Output, Channel D
Functional Diagram
Internal ESD Protection
VDD
IN-
60Ω
MAX40079
MAX40087
½ MAX40077
½ MAX40089
OUT
IN+
60Ω
VSS
www.maximintegrated.com
SHDN
Maxim Integrated │ 11
MAX40079/MAX40087/
MAX40077/MAX40089/
MAX40078
Detailed Description
The
MAX40079/MAX40087/MAX40077/MAX40089/
MAX40078 single/dual/quad channel operational amplifiers
feature ultra-low noise and distortion. Their low distortion
and low noise make them ideal for use as pre-amplifiers
in wide dynamic range applications, such as 16-bit analogto-digital converters. Their high input impedance and low
noise are also useful for signal conditioning of high-impedance
sources, such as piezoelectric transducers.
These devices have true rail-to-rail output operation, drive
output resistive loads as low as 1kΩ while maintaining DC
accuracy and can drive capacitive loads up to 200pF without
any oscillation. The input common-mode voltage range
extends from 0.2V below VSS to (VDD - 1.5V). The pushpull output stage maintains excellent DC characteristics,
while delivering up to ±20 mA of source/sink output current.
The MAX40079/MAX40079/MAX40078 are single/dual/
quad respectively that are unity-gain stable, while the
MAX40087/MAX40089, single/dual respectively are
decompensated version having higher slew rate and are
stable for Gain ≥ 5V/V. The MAX40079/MAX40087 single
channel op amps feature a low-power shutdown mode,
which reduces the supply current to 0.1μA and places
amplifiers outputs into a high impedance state.
Low Noise
The amplifiers input-referred voltage noise density is
dominated by flicker noise(also known as 1/f noise)
at lower frequencies and by thermal noise at higher
frequencies. Overall thermal noise contribution is affected
by the parallel combination of resistive feedback network
(RF||RG) depicted in Figure 1. These resistors should be
reduced in cases where system bandwidth is large and
thermal noise is dominant. Noise contribution factor can
be reduced with increased gain settings.
For example, the input noise voltage density (eN) of the
circuit with RF = 100kΩ, RG = 10kΩ with Gain = 11V/V
non-inverting configuration is eN = 12nV/√Hz.
eN can be reduced to 6nV/√Hz by choosing RF = 10kΩ,
smaller RG = 1kΩ compared to 10kΩ with still same Gain
= 11V/V but at the expense of higher current consumption
and higher distortion. Noise of this circuit is effectively
reduced due to smaller value of RG that dominates
system noise.
Having a Gain of 101V/V with RF = 100kΩ, RG = 1kΩ,
input referred voltage noise density is still a low 6nV/√Hz
as the noise dominating resistor RG remained the same.
www.maximintegrated.com
Single/Dual/Quad Ultra-Low
Input Bias Current,
Low-Noise Amplifiers
Low Distortion
Many factors can affect the noise and distortion
performance of the amplifier based on the design choices
made. The following guidelines offer valuable information
on the impact of design choices on total harmonic distortion
(THD). Choosing correct feedback and gain resistor
values for a particular application can be a very important
factor in reducing THD. In general, the smaller the closedloop gain, the smaller the THD generated, especially
when driving heavy resistive loads (in other words, smaller
resistive load with higher output current). Operating the
device near or above the full-power bandwidth significantly
degrades distortion.
Referencing the load to either supply also improves the
amplifier distortion performance, because only one of the
MOSFETs of the push-pull output stage drives the output.
Referencing the load to mid-supply increases the amplifier
distortion for a given load and feedback setting (See the
Total Harmonic Distortion vs. Frequency graph in the
Typical Operating Characteristics).
For gains ≥ 5V/V, the de-compensated MAX40087/
MAX40089 deliver the best distortion performance as they
have a higher slew rate and provide a higher amount of
loop gain for a given closed-loop gain setting. Capacitive
loads below 100pF do not significantly affect distortion
results. Distortion performance is relatively constant over
supply voltages.
Input Protection
As per Functional Diagram, when voltage on either of the
input pins goes up or below VDD or VSS by more than a diode
voltage drop, ESD diodes begin to turn-on/forward bias
and large amount of current flow through these diodes. If
op amp inputs in certain applications are subject to these
over-voltage conditions, insert a series current limiting 50
ohm resistors on either inputs. However, note that DC
precision of the system be affected due to these series resistors
and also thermal noise of these resistors need to be considered
while making noise analysis of the entire circuit.
An input differential protection scheme is used (refer to
Functional Diagram) that protect the device if there is a
large differential voltage applied across input pins. A series
of 60Ω resistors are used in conjunction with a pair of
back to back diodes that turn on in an event of differential
voltage beyond a diode drop. A pair of 60Ω resistors limit
current flowing through these diodes so that the current is
limited below abs max rating of ±20mA.
Maxim Integrated │ 12
MAX40079/MAX40087/
MAX40077/MAX40089/
MAX40078
Single/Dual/Quad Ultra-Low
Input Bias Current,
Low-Noise Amplifiers
VDD = 5V
IN+
MAX40079/
½MAX40077
VIN
VOUT
INRG
VSS = 0V
SHDN =5V
RF
CZ
Figure 1. Adding Feed-Forward Compensation
Since there is a differential protection scheme used in
these family of op amps, these amplifiers cannot be used
as comparators in open loop, which is often a possibility
on an unused channel of op amp.
Using a Feed-Forward Compensation
Capacitor, CZ
The amplifier’s input capacitance is 7pF and if the
resistance seen by the inverting input is large (Figure
1) as a result of feedback network, this resistance and
capacitance combination can introduce a pole within the
amplifier’s bandwidth resulting in reduced phase margin.
Compensate the reduced phase margin by introducing
a feed-forward capacitor (CZ) between the inverting
input and the output (shown in Figure 1). This effectively
cancels the pole from the inverting input of the amplifier.
Choose the value of CZ as follows:
CZ = 10 x (RF/RG) [pF]
In the unity-gain stable: MAX40079/MAX40077/MAX40078,
the use of correct value CZ is most important for closed
loop non-inverting gain AV = +2V/V, and inverting gain AV
= -1V/V.
In the de-compensated MAX40087/MAX40089, CZ is
most important for closed loop gain AV = +10V/V.
www.maximintegrated.com
Using a slightly smaller CZ than suggested by the formula
above achieves a higher bandwidth at the expense of
reduced phase and gain margin. As a general guideline,
consider using CZ for cases where RG||RF is greater than
20kΩ (for MAX40079/MAX40077/MAX40078) and greater
than 5kΩ (for MAX40087/MAX40089).
Applications Information
The
MAX40079/MAX40087/MAX40077/MAX40089/
MAX40078 family of op amps combine good driving
capability that can also support ground/low-side sensing
input and rail-to-rail output operation. With their low distortion and low noise, they are ideal for use in ADC buffers,
DAC output buffers, medical instrumentation systems and
other noise-sensitive applications.
However, there are two main application areas where
these ultra-low input bias current op amps find place and
they are to measure high impedance measurements.
High Impedance measurements can be interfacing either
Current output sensors or voltage output sensors that
would need very high output resistance to be interfaced
with. These op amps offer just that as the input impedance of these amplifiers is in the range of 1000GΩ.
Voltage output sensors readout can be accomplished with
unity gain buffer configuration and current output sensors
like photo-diodes current read out can be accomplished
in transimpedance amplifier configuration discussed later
in this data sheet.
Ground-Sensing and Rail-to-Rail Outputs
The common-mode input range of these devices extends
below ground over temperature that offers excellent common mode rejection and can be used in low side current
sensing applications. These devices are guaranteed not
to undergo phase reversal when the input is overdriven
over input common mode voltage range as shown in
Figure 2.
Figure 3 showcases the true rail-to-rail output operation of
the amplifier, configured with AV = 5V/V. The output swings
to within 8mV of the supplies with a 10kΩ load, making the
devices ideal in low-supply voltage applications.
Maxim Integrated │ 13
MAX40079/MAX40087/
MAX40077/MAX40089/
MAX40078
Single/Dual/Quad Ultra-Low
Input Bias Current,
Low-Noise Amplifiers
Figure 2. Scope Plot Showing Overdriven Input with No Phase
Reversal
Figure 3. Rail-to-Rail Output Operation with 10kΩ
RSERIES
IP
IP
CJ
PHOTODIODE
RSHUNT
EQUIVALENT CIRCUIT
CJ
SIMPLIFIED EQUIVALENT
CIRCUIT
Figure 4. Photodiode Equivalent Circuit Showing Parasitics
Typical Application Circuit
Extremely Low-Leakage Op Amp (~50fA) Used as
Transimpedance Amplifier
The ultra-low input bias current and low noise profile
makes it an excellent choice for high impedance applications. It should be noted that unity gain stable is not a
requirement for TIA applications. MAX40087/MAX40089
with increased GBW of 42MHz (min AV ≥ 5V/V) may also
be an option.
Figure 6 shows a transimpedance amplifier using
MAX40077 suited for low to moderate TIA applications in
www.maximintegrated.com
photo-voltaic mode with buffered reference. This enables
negligible reverse-voltage across the photodiode which
ensures little to no dark current. A typical bias point of
100mV–200mV may be used to ensure the output of
amplifier to be in linear range. Because of the nature of
photo-diode in photo-voltaic modes, the input capacitance is more as compared to photo-conductive mode.
Therefore, this mode is chosen for slower to moderate
photo-diode current applications but this methodology
provides high linearity, better accuracy and low noise
performance.
Maxim Integrated │ 14
MAX40079/MAX40087/
MAX40077/MAX40089/
MAX40078
Single/Dual/Quad Ultra-Low
Input Bias Current,
Low-Noise Amplifiers
Photodiode Equivalent Circuit (Figure 4):
IP is current flowing through photodiode proportional to
intensity of light on photodiode sensor
CJ is the junction input capacitance of the photodiode
RSHUNT is the internal shunt resistance of the photodiode
RSERIES is the internal series resistance of the photodiode
is required to add a zero to compensate for the phase
shift. To learn more about Trans-impedance amplifier
stabilization, please refer to the app note: AN5129:
Stabilize your Transimpedance Amplifier.
For a critically damped system the f-3dB =
√(GBW/(2 x π x R1 x (C1 + CJ)) and the value of C1
where VOUT = IP x R1
= √(CJ/2 x π x R1 x GBW) .
where same equation still applies VOUT = IP x R1
When using MAX40087 de-compensated Op-Amp, care
must be taken that the noise gain (1 + CJ/C1) at higher
frequencies is higher than gain of 5V/V in order to stabilize
the TIA.
The input capacitance of the diode can destabilize the
amplifier when choosing R1 in such a way that 1/(2 x π x
R1 x CJ) < GBW of the op amp. A feedback capacitance
C1
The noise contribution of R1 can be reduced by increasing
the C1 value, but this lowers the bandwidth. A careful
trade-off must be done to improve the signal-to-noise
ratio (SNR).
R1
5V
D1
Output Buffering of an Un-Buffered DAC:
MAX40079
5V
Noise Consideration: choosing lower R1 will provide lower
transimpedance and higher BW, but this may result in
higher noise as the signal reduces by a factor of R1 and
noise reduces by factor of √R1.
R2
R3
Figure 5. Single-Supply Transimpedance Amplifier Configuration
with Single-Channel Op Amp
The Figure 7 shows the single MAX40079 configured as
an output buffer for the MAX5541 16-bit DAC. Because
the MAX5541 has an unbuffered voltage output, the
input bias current of the op amp used must be less than
6nA to maintain 16-bit accuracy. This family of amplifiers
have an input bias current of only 160pA (max) over
temperature, virtually eliminating this as a source of error. In
addition, the MAX40079 has excellent open loop gain and
common-mode rejection, making this an excellent output
buffer amplifier.
C1
R1
5V
5V
D1
R2
½
MAX40077
½
MAX40077
R3
Figure 6. Single-Supply Transimpedance Amplifier Configuration with Dual-Channel Op Amp
www.maximintegrated.com
Maxim Integrated │ 15
MAX40079/MAX40087/
MAX40077/MAX40089/
MAX40078
Single/Dual/Quad Ultra-Low
Input Bias Current,
Low-Noise Amplifiers
VDD=5V
VREF=2.5V
VDD=5V
CS
SERIAL
INTERFACE
VDD
REF
MAX5541
SCLK
DIN DGND
OUT
IN+
MAX40079
AGND
0V TO +2.5V
OUTPUT
INVSS=0V
SHDN =5V
Figure 7. DAC Output Buffering with Op Amp
Capacitive Load Stability
The MAX40079 family of op amps drive up to 50pF in
all configurations without any oscillation. Driving higher
capacitive loads than 50pF might lead to oscillation in
certain configurations due to reduction in phase margin
and it can be seen as overshoot and undershoot with a
step response on oscilloscope. If the application demands
for the op amp to drive more than 50pF capacitive loads,
it is recommended to add a series isolation resistor of
10-50Ω on the op amp output before capacitive load. Size
of this resistor depends on the amount of capacitive load
op amp is driving. Please refer to Isolation Resistance
vs. Capacitive Stability graph in Typical Operating
Characteristics for more information on resistance sizing.
This series isolation resistance is very useful in unity gain
buffer configuration when full scale signal output swing is
used as the unity gain configuration is the worst case for
stability while driving capacitive loads.
Flux and Solder Contaminant Removal
Upon soldering process of the op amp on the PCB,
remains of solder flux is a major performance degrading
factor in measuring ultra-low input bias currents in the
order of 50fA. Solvents like isopropyl alcohol (IPA) are
effective in cleaning up solder flux contaminants. Upon
clearly rubbing off the solder flux areas with IPA, ultrasonic
www.maximintegrated.com
cleaning in bath is highly recommended. Once the bath is
completed, it can be dried up either at room temperature
for several hours or placing the cleaned up PCB in an
oven at elevated temperature for quick usage.
Power Supplies and Layout
The
MAX40079/MAX40087/MAX40077/MAX40089/
MAX40078 op amps operate from a single +2.7V to
+5.5V power supply or from dual supplies of ±1.35V to
±2.75V. For single-supply operation, bypass the VDD power
supply pin with a 0.1μF ceramic capacitor placed close to
the VDD pin. If operating from dual supplies, bypass both
VDD and VSS supply pins with 0.1μF ceramic capacitor
to ground. If additional decoupling is needed add another
4.7μF or 10μF where supply voltage is applied on PCB.
Good layout improves performance by decreasing
the amount of stray capacitance and noise at the op
amp inputs and output. To decrease stray capacitance,
minimize PC board trace lengths and resistor leads, and
place external components close to the op amp’s pins.
Guard rings and Shielding is highly recommended to
guard the high impedance input traces against input leakage current. Refer to MAX40077 EV kit data sheet for
more information on this. This is accomplished using a
Triax connector and drving it's guard to the same potential
as the signal on high impedance input.
Maxim Integrated │ 16
MAX40079/MAX40087/
MAX40077/MAX40089/
MAX40078
Single/Dual/Quad Ultra-Low
Input Bias Current,
Low-Noise Amplifiers
Ordering Information
NUMBER OF
CHANNELS
TEMP RANGE
MAX40079ANT+T
Single
MAX40079AUT+T
Single
MAX40087ANT+T
Single
MAX40087AUT+T
Single
MAX40077ANA+T
Dual
MAX40077AUA+T
Dual
MAX40089ANA+T
Dual
MAX40089AUA+T
Dual
MAX40078AUD+T
MAX40077AUA/V+T*
MAX40089AUA/V+T*
PART NUMBER
PIN-PACKAGE
[STABLE GAIN V/V]
[GAIN BANDWIDTH
PRODUCT IN MHZ]
-40°C to +125°C
6-WLP
1
10
-40°C to +125°C
6-SOT23
1
10
-40°C to +125°C
6-WLP
5
42
-40°C to +125°C
6-SOT23
5
42
-40°C to +125°C
8-WLP
1
10
-40°C to +125°C
μMAX-8
1
10
-40°C to +125°C
8-WLP
5
42
-40°C to +125°C
μMAX-8
5
42
Quad
-40°C to +125°C
14 TSSOP
1
10
Dual
-40°C to +125°C
μMAX-8
1
10
Dual
-40°C to +125°C
μMAX-8
5
42
/V denotes an automotive qualified part.
* Denotes Future Product-Contact Maxim for availability
+Denotes a lead(Pb)-free/RoHS-compliant package.
T = Denotes tape-and-reel.
www.maximintegrated.com
Maxim Integrated │ 17
MAX40079/MAX40087/
MAX40077/MAX40089/
MAX40078
Single/Dual/Quad Ultra-Low
Input Bias Current,
Low-Noise Amplifiers
Revision History
REVISION
NUMBER
REVISION
DATE
DESCRIPTION
PAGES
CHANGED
0
1/18
Initial release
1
3/18
Updated Electrical Characteristics and Ordering Information tables
—
2
5/18
Updated future product status of MAX40078AUD+T in Ordering Information table
16
3
7/18
Updated General Description section and Ordering Information table
16
4
3/19
Updated Ordering Information
5
7/19
Updated Pin Configuration diagram and Pin Description table
6
11/19
Updated Pin Configuration, Pin Description, and Ordering Information
7
1/20
Updated Pin Configuration and Ordering Information
9, 16
8
4/20
Updated Benefits and Features, added package outline drawing
1, 3
9
6/21
Updated Ordering Information table.
17
10
10/21
Updated Electrical Characteristics table
5
3, 4, 6, 8, 16
16
9, 10
9, 10, 16
Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is
assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties that
may result from its use.Specifications subject to change without notice. No license is granted by implicationor
otherwise under any patent or patent rights of Analog Devices. Trademarks andregistered trademarks are the
property of their respective owners.
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