General Description
The single MAX4036/MAX4037 and dual MAX4038/
MAX4039 operational amplifiers operate from a single
+1.4V to +3.6V (without reference) or +1.8V to +3.6V (with
reference) supply and consume only 800nA of supply
current per amplifier, and 1.1µA for the optional refer-
ence. The MAX4036/MAX4038 feature a common-mode
input voltage range from 0V to VDD - 0.4V at VDD = 1.4V.
The MAX4037/MAX4039 feature a 1.232V voltage refer-
ence capable of sourcing 100µA and sinking 20µA.
The MAX4036–MAX4039s’ rail-to-rail outputs drive 5kΩ
loads to within 25mV of the rails. Ultra-low supply current,
low operating voltage, and rail-to-rail outputs make the
MAX4036–MAX4039 ideal for use in single-cell lithium-ion
(Li+), or two-cell NiCd/NiMH/alkaline battery-powered
applications.
The MAX4036 is available in an SC70 package, the
MAX4037 in a SOT23 package, and the MAX4038/
MAX4039 in UCSP™, µMAX®, and TDFN packages.
Applications
Battery-Powered/Solar-Powered Systems
Portable Medical Instrumentation
Pagers and Cell Phones
Micropower Thermostats and Potentiostats
Electrometer Amplifiers
Remote Sensor Amplifiers
Active Badges
pH Meters
Features
♦Ultra-Low 800nA per Amplifier Supply Current
♦Ultra-Low 1.4V Supply Voltage Operation (1.8V for
MAX4037/MAX4039)
♦Rail-to-Rail Outputs Drive 5kΩand 5000pF Load
♦1.232V ±0.5%, 120ppm/°C (max) Reference
(MAX4037/MAX4039)
♦No External Reference Bypass Capacitor
Required
♦No Phase Reversal for Overdriven Inputs
♦Low 1.0pA (typ) Input Bias Current
♦Low 200µV Input Offset Voltage
♦Unity-Gain Stable
♦Available in Tiny UCSP, SC70, SOT23, TDFN, and
µMAX Packages
♦Available in -40°C to +125°C Temperature Range
(MAX4036A/MAX4038A)
MAX4036–MAX4039
Low IBIAS, +1.4V/800nA, Rail-to-Rail Op Amps
with +1.2V Buffered Reference
________________________________________________________________ Maxim Integrated Products 1
INA+ SENSOR
REF
THREE-ELECTRODE POTENTIOSTAT APPLICATION
INB+
OUTA
INB-
OUTB
INA-
VDD
VSS
MAX4039
3V
ADC
Typical Operating Circuit
Ordering Information
MAX4039
OUTA
REF
INA-
INA+
VSS
OUTB
INB-
INB+
VDD
REF
Functional Diagram
19-3142; Rev 4; 3/06
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
+Denotes lead-free package.
*EP = Exposed paddle.
Ordering Information continued at end of data sheet.
µMAX is a registered trademark and UCSP is a trademark of
Maxim Integrated Products, Inc.
PART
TEMP RANGE
PIN-
PACKAGE
TOP
MARK
MAX4036EXK-T
-40°C to +85°C
5 SC70-5
AFR
MAX4036AAXK+T
-40°C to +125°C
5 SC70-5
ASN
MAX4037EUT-T
-40°C to +85°C
6 SOT23-6
ABRX
MAX4038ETA-T
-40°C to +85°C
8 TDFN-EP*
AGO
MAX4038EUA
-40°C to +85°C
8 µMAX —
MAX4038EBL-T
-40°C to +85°C
9 UCSP-9
AEG
MAX4038AAUA
-40°C to +125°C
8 µMAX —
Pin Configurations and Selector Guide appear at end of
data sheet.
MAX4036–MAX4039
Low IBIAS, +1.4V/800nA, Rail-to-Rail Op Amps
with +1.2V Buffered Reference
2_______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(VDD = +3V, VSS = VCM = 0V, VOUT_ = VDD/2, RLto VDD/2, CL= 15pF, TA= +25°C,unless otherwise specified.)
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.
VDD to VSS .............................................................-0.3V to +4.0V
INA+, INB+, INA-, INB-, IN+, IN-, OUTA,
OUTB, OUT, REF .........................(VSS - 0.3V) to (VDD + 0.3V)
OUTA, OUTB, OUT, REF Shorted to VSS or VDD .......Continuous
Maximum Continuous Power Dissipation (TA= +70°C)
5-Pin SC70 (derate 3.1mW/°C above +70°C)..............247mW
6-Pin SOT23 (derate 8.7mW/°C above +70°C)............696mW
8-Pin µMAX (derate 4.5mW/°C above +70°C) .............362mW
8-Pin TDFN (derate 24.4mW/°C above +70°C) .........1951mW
9-Bump UCSP (derate 5.2mW/°C above +70°C).........412mW
10-Pin µMAX (derate 5.6mW/°C above +70°C) ...........444mW
10-Pin TDFN (derate 24.4mW/°C above +70°C) .......1951mW
Operating Temperature Range
MAX403_E_ _...................................................-40°C to +85°C
MAX403_A_ _ ................................................-40°C to +125°C
Junction Temperature .....................................................+150°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
PARAMETER
SYMBOL
CONDITIONS
MIN TYP MAX
MAX4036/MAX4038, guaranteed by PSRR
tests 1.4 3.6
Supply Voltage Range VDD MAX4037/MAX4039, guaranteed by PSRR
and line regulation tests 1.8 3.6
V
VDD = 1.4V 0.8 1.2
MAX4036 VDD = 3.6V 0.9 1.3
VDD = 1.8V 1.9 2.4
MAX4037 VDD = 3.6V 2.0 2.5
VDD = 1.4V 1.7 2.3
MAX4038 VDD = 3.6V 1.9 2.5
VDD = 1.8V 2.8 4.0
Supply Current IDD
MAX4039 VDD = 3.6V 3.0 4.1
µA
OPERATIONAL AMPLIFIERS
Input Offset Voltage VOS
±0.2 ±2.0
mV
Input Bias Current IB(Note 1)
±1.0
±10 pA
Input Offset Current IOS (Note 1)
±0.3
±20 pA
V
D D
= 1.4V
( M AX 4036/M AX 4038 onl y) VSS
VDD -
0.4
VDD = 1.8V
VSS
VDD -
0.3
Input Common-Mode Voltage
Range VCM Guaranteed by
CMRR test
VDD = 3.3V
VSS
VDD -
0.2
V
VDD = 1.4V, VSS ≤ VCM ≤ (VDD - 0.4V)
(MAX4036/MAX4038 only) 50 70
VDD = 1.8V, VSS ≤ VCM ≤ (VDD - 0.3V) 50 70
Common-Mode Rejection Ratio CMRR
VDD = 3.3V, VSS ≤ VCM ≤ (VDD - 0.2V) 56 76
dB
1.4V ≤ VDD ≤ 3.6V (MAX4036/MAX4038
only) 62 82
Power-Supply Rejection Ratio PSRR
1.8V ≤ VDD ≤ 3.6V 62 84
dB
MAX4036–MAX4039
Low IBIAS, +1.4V/800nA, Rail-to-Rail Op Amps
with +1.2V Buffered Reference
_______________________________________________________________________________________ 3
ELECTRICAL CHARACTERISTICS (continued)
(VDD = +3V, VSS = VCM = 0V, VOUT_ = VDD/2, RLto VDD/2, CL= 15pF, TA= +25°C,unless otherwise specified.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
RL = 100kΩ, 50mV ≤ VOUT ≤ (VDD - 50mV)
80 108
Large-Signal Voltage Gain AVOL
RL = 5kΩ, 150mV ≤ VOUT ≤ (VDD - 150mV)
78 105 dB
RL = 100kΩ25
Output Voltage Swing High
VDD - VOH
RL = 5kΩ25 50 mV
RL = 100kΩ25
Output Voltage Swing Low
VOL - VSS
RL = 5kΩ25 50 mV
Output Short-Circuit Current ISCO To VDD or VSS
±13
mA
Gain-Bandwidth Product GBW 4 kHz
Phase Margin θM90
Degrees
Slew Rate SR 4
V/ms
Power-On Time tON (Note 3)
0.25
ms
Input Noise-Voltage Density enf = 1kHz 500
nV/√Hz
Capacitive-Load Stability CLOAD AVCL = 1V/V, no sustained oscillations
5000
pF
REFERENCE (MAX4037/MAX4039)
Reference Voltage VREF
1.226 1.232 1.238
V
Line Regulation ∆VREF/
∆VDD VDD = +1.8V to +3.6V 0.3 %/V
0 ≤ ILOAD ≤ 100µA, sourcing
0.0015
Load Regulation ∆VREF/
∆ILOAD -20µA ≤ ILOAD ≤ 0, sinking
0.0075
%/µA
Reference Output Voltage Noise
en0.1Hz to 10Hz 60
µVP-P
Short to VDD
0.25
Output Short-Circuit Current ISCR Short to VSS 1.9 mA
Capacitive-Load Stability Range
CLOAD (Note 1) 0 250 pF
ELECTRICAL CHARACTERISTICS
(VDD = +3V, VSS = VCM = 0V, VOUT_ = VDD/2, RLto VDD/2, CL= 15pF, TA= TMIN to TMAX,unless otherwise specified.) (Note 2)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
MAX4036/MAX4038, guaranteed by PSRR
test 1.4 3.6
Supply Voltage Range VDD MAX4037/MAX4039, guaranteed by PSRR
and line regulation tests 1.8 3.6
V
VDD = 1.4V 1.7
MAX4036 VDD = 3.6V 1.8
VDD = 1.4V 2.0
MAX4036A VDD = 3.6V 2.1
VDD = 1.8V 3.1
Supply Current IDD
MAX4037 VDD = 3.6V 3.2
µA
ELECTRICAL CHARACTERISTICS (continued)
(VDD = +3V, VSS = VCM = 0V, VOUT_ = VDD/2, RLto VDD/2, CL= 15pF, TA= TMIN to TMAX,unless otherwise specified.) (Note 2)
PARAMETER
SYMBOL
CONDITIONS
MIN TYP MAX
UNITS
VDD = 1.4V 2.9
MAX4038 VDD = 3.6V 3.2
VDD = 1.4V 3.4
MAX4038A VDD = 3.6V 3.7
VDD = 1.8V 5.2
Supply Current IDD
MAX4039 VDD = 3.6V 5.3
µA
OPERATIONAL AMPLIFIERS
Input Offset Voltage VOS ±8 mV
Input Offset Voltage Temperature
Coefficient TCVOS ±1
µV/°C
Input Bias Current IB
±100
pA
Input Offset Current IOS
±200
pA
VDD = 1.4V
(MAX4036/MAX4038 only) VSS
VDD -
0.4
VDD = 1.8V
VSS
VDD -
0.4
Input Common-Mode Voltage
Range VCM Guaranteed by
CMRR test
VDD = 3.3V
VSS
VDD -
0.2
V
VDD = 1.4V, VSS ≤ VCM ≤ (VDD - 0.5V)
(MAX4036/MAX4038 only) 44
VDD = 1.8V, VSS ≤ VCM ≤ (VDD - 0.4V) 50
Common-Mode Rejection Ratio CMRR
VDD = 3.3V, VSS ≤ VCM ≤ (VDD - 0.3V) 52
dB
1.4V ≤ VDD ≤ 3.6V
(MAX4036/MAX4038 only) 60
Power-Supply Rejection Ratio PSRR
1.8V ≤ VDD ≤ 3.6V 60
dB
RL = 100kΩ, 50mV ≤ VOUT ≤ (VDD - 50mV) 75
Large-Signal Voltage Gain AVOL
RL = 5kΩ, 150mV ≤ VOUT ≤ (VDD - 150mV) 73
dB
RL = 100kΩ10
Output Voltage Swing High
VDD - VOH
RL = 5kΩ
100
mV
RL = 100kΩ10
Output Voltage Swing Low
VOL - VSS
RL = 5kΩ
100
mV
REFERENCE (MAX4037/MAX4039)
MAX4037EUT-T, MAX4039ETB,
MAX4039EUB 25
120
Reference Voltage Temperature
Coefficient
TCVREF (Note 1)
MAX4039EBL-T 35
200
ppm/°C
Line Regulation ∆VREF/
∆VDD VDD = 1.8V to 3.6V 0.6 %/V
0 ≤ ILOAD ≤ 100µA, sourcing
0.003
Load Regulation ∆VREF/
∆ILOAD
-20µA ≤ ILOAD ≤ 0, sinking
0.015
%/µA
Capacitive-Load Stability Range
CLOAD (Note 1) 0
250
pF
Note 1: Guaranteed by design.
Note 2: All devices are production tested at TA= +25°C. All temperature limits are guaranteed by design.
Note 3: Output settles within 1% of final value.
MAX4036–MAX4039
Low IBIAS, +1.4V/800nA, Rail-to-Rail Op Amps
with +1.2V Buffered Reference
4_______________________________________________________________________________________
MAX4036–MAX4039
Low IBIAS, +1.4V/800nA, Rail-to-Rail Op Amps
with +1.2V Buffered Reference
_______________________________________________________________________________________ 5
MAX4036
SUPPLY CURRENT
vs. SUPPLY VOLTAGE AND TEMPERATURE
MAX4036 toc01
SUPPLY VOLTAGE (V)
SUPPLY CURRENT (µA)
3.02.62.21.8
0.4
0.8
1.2
1.6
0
1.4 3.4
TA = +85°C
TA = -40°C
TA = +25°C
MAX4037
SUPPLY CURRENT
vs. SUPPLY VOLTAGE AND TEMPERATURE
MAX4036 toc02
SUPPLY VOLTAGE (V)
SUPPLY CURRENT (µA)
3.33.02.72.42.1
0.5
1.0
1.5
2.0
2.5
3.0
0
1.8 3.6
TA = +85°C
TA = -40°C
TA = +25°C
MAX4038
SUPPLY CURRENT
vs. SUPPLY VOLTAGE AND TEMPERATURE
MAX4036 toc03
SUPPLY VOLTAGE (V)
SUPPLY CURRENT (µA)
3.02.62.21.8
0.5
1.5
1.0
2.0
2.5
3.0
0
1.4 3.4
TA = +85°C
TA = -40°C
TA = +25°C
MAX4039
SUPPLY CURRENT
vs. SUPPLY VOLTAGE AND TEMPERATURE
MAX4036 toc04
SUPPLY VOLTAGE (V)
SUPPLY CURRENT (µA)
3.33.02.72.42.1
1
2
4
3
5
0
1.8 3.6
TA = +85°C
TA = -40°C
TA = +25°C
OFFSET VOLTAGE
vs. COMMON-MODE VOLTAGE
MAX4036 toc05
COMMON-MODE VOLTAGE (V)
OFFSET VOLTAGE (mV)
21
0.2
0.4
0.6
0.8
1.0
0
03
VDD = 1.4V
VDD = 1.8V VDD = 3.0V
OFFSET VOLTAGE
vs. TEMPERATURE
MAX4036 toc06
TEMPERATURE (°C)
OFFSET VOLTAGE (mV)
603510-15
-0.20
-0.10
0
0.10
0.20
0.30
-0.30
-40 85
INPUT BIAS CURRENT
vs. TEMPERATURE
MAX4036 toc07
TEMPERATURE (°C)
INPUT BIAS CURRENT (pA)
603510-15
0
10
20
30
40
-10
-40 85
VCM = 3V
VCM = 0V
INPUT BIAS CURRENT
vs. COMMON-MODE VOLTAGE
MAX4036 toc08
COMMON-MODE VOLTAGE (V)
INPUT BIAS CURRENT (pA)
2.52.01.51.00.5
10
20
30
40
0
0 3.0
TA = +25°C
TA = +85°C
-10
-100
10 10k1k100
OP AMP POWER-SUPPLY REJECTION RATIO
vs. FREQUENCY
-70
-90
-30
-50
0
-60
-80
-20
-40
MAX4036 toc09
FREQUENCY (Hz)
PSRR (dB)
AV = 1V/V
Typical Operating Characteristics
(VDD = 3V, VSS = VCM = 0V, RLto VDD/2, TA= +25°C, unless otherwise noted.)
MAX4036–MAX4039
Low IBIAS, +1.4V/800nA, Rail-to-Rail Op Amps
with +1.2V Buffered Reference
6_______________________________________________________________________________________
OUTPUT VOLTAGE SWING HIGH
vs. TEMPERATURE
MAX4036 toc10
TEMPERATURE (°C)
VDD - VOH (mV)
603510-15
5
10
15
20
25
30
0
-40 85
RL = 5kΩ
RL = 100kΩ
OUTPUT VOLTAGE SWING LOW
vs. TEMPERATURE
MAX4036 toc11
TEMPERATURE (°C)
VOL - VSS (mV)
603510-15
5
10
15
20
25
30
35
0
-40 85
RL = 100kΩ
RL = 5kΩ
AV
vs. OUTPUT SWING LOW
MAX4036 toc12
VOL (mV)
AV (dB)
400300100 200
60
80
100
120
140
40
0500
RL = 5kΩ
RL = 100kΩ
AV
vs. OUTPUT SWING HIGH
MAX4036 toc13
VDD - VOH (mV)
AV (dB)
400300100 200
60
80
100
120
140
40
0500
RL = 5kΩ
RL = 100kΩ
AV
vs. TEMPERATURE
MAX4036 toc14
TEMPERATURE (°C)
AVOL (dB)
603510-15
20
40
60
80
100
120
140
0
-40 85
RL = 100kΩ
RL = 5kΩ
0
-100
0 0.1 10k 100k
CROSSTALK
vs. FREQUENCY
-60
-80
-40
-20
MAX4036 toc15
FREQUENCY (Hz)
CROSSTALK (dB)
1k
RL = 5kΩ
RL = 100kΩ
AV = 1V/V
MAX4038/MAX4039
100
0.01
0.01 0.1 10 100
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. FREQUENCY
0.1
1
10
MAX4036 toc16
FREQUENCY (kHz)
THD+N (%)
1
AV = 1V/V
VIN_ = VDD/2
VOUT = 2.5VP-P
RL = 100kΩ TO VSS
VOUT = 2.5VP-P
RL = 5kΩ TO VSS
100,000
100
10k 100k 1M
OP AMP STABILITY
vs. CAPACITIVE AND RESISTIVE LOADS
MAX4036 toc17
RESISTIVE LOAD (Ω)
CAPACITIVE LOAD (pF)
1000
10,000
STABLE
REGION RL TO VSS
UNSTABLE
REGION
OP AMP SINK CURRENT
vs. OUTPUT VOLTAGE
MAX4036 toc18
VOUT_ (V)
SINK CURRENT (mA)
2.41.81.20.6
2
4
6
8
10
12
14
0
0 3.0
VDD = 3.0V
VDD = 1.8V
VID = -100mV
Typical Operating Characteristics (continued)
(VDD = 3V, VSS = VCM = 0V, RLto VDD/2, TA= +25°C, unless otherwise noted.)
MAX4036–MAX4039
Low IBIAS, +1.4V/800nA, Rail-to-Rail Op Amps
with +1.2V Buffered Reference
________________________________________________________________________________________ 7
OP AMP SOURCE CURRENT
vs. OUTPUT VOLTAGE
MAX4036 toc19
VOUT_ (V)
SOURCE CURRENT (mA)
2.41.81.20.6
2
4
6
8
10
12
14
16
18
0
03.0
VDD = 3.0V
VDD = 1.8V
VID = +100mV
1000
0.1
10 1k 10k
OP AMP VOLTAGE NOISE DENSITY
vs. FREQUENCY
1
10
100
MAX4036 toc20
FREQUENCY (Hz)
NOISE (µV/√Hz)
100
OP AMP
SMALL-SIGNAL TRANSIENT RESPONSE
MAX4036 toc21
2.55V
2.45V
2.55V
2.45V
VIN+
VOUT_
AV = 1V/V
CL = 12pF TO VSS
RL = 1MΩ TO VSS
OP AMP
SMALL-SIGNAL TRANSIENT RESPONSE
MAX4036 toc22
40µs/div
AV = 1V/V
CL = 250pF TO VSS
RL = 1MΩ TO VSS
VIN+
VOUT_
2.55V
2.45V
2.55V
2.45V
OP AMP
LARGE-SIGNAL TRANSIENT RESPONSE
MAX4036 toc23
100µs/div
AV = 1V/V
CL = 12pF TO VSS
RL = 1MΩ TO VSS
VIN+
VOUT_
500mV/div
2.5V
1.5V
OP AMP
TURN-ON TRANSIENT RESPONSE
MAX4036 toc24
100µs/div
3.0V
0V
VOUT_
50mV/div
AV = 1V/V
CL = 12pF TO GND
RL = 1MΩ TO GND
VIN+ = VDD / 2
VDD
Typical Operating Characteristics (continued)
(VDD = 3V, VSS = VCM = 0V, RLto VDD/2, TA= +25°C, unless otherwise noted.)
MAX4036–MAX4039
Low IBIAS, +1.4V/800nA, Rail-to-Rail Op Amps
with +1.2V Buffered Reference
8_______________________________________________________________________________________
80
70
60
50
40
30
20
10
0
-10
-20
-30
-40
110100 1k 10k 100k
GAIN AND PHASE
vs. FREQUENCY
MAX4036 toc25
FREQUENCY (Hz)
GAIN (dB)
180
135
90
45
0
-45
-90
-135
PHASE (DEGREES)
AV = 1000V/V
VIN_ = 1mVP-P
GAIN
PHASE
2
-30
100 10k 100k
LARGE-SIGNAL GAIN
vs. FREQUENCY
-22
-26
-18
-14
-10
-6
-2
MAX4036 toc26
FREQUENCY (Hz)
GAIN (dB)
1k
RL = 1MΩ
AV = 1
VOUT_ = 1VP-P
CL = 12pF
RL = 100kΩ
RL = 5kΩ
REFERENCE VOLTAGE
vs. TEMPERATURE
MAX4036 toc27
TEMPERATURE (°C)
VREF (V)
603510-15
1.228
1.230
1.232
1.234
1.236
1.226
-40 85
MAX4037/MAX4039
REFERENCE VOLTAGE CHANGE
vs. TIME
MAX4036 toc28
TIME (HR)
VREF (V)
500400300200100
1.231
1.232
1.233
1.234
1.230
0600
MAX4037
MAX4039
REFERENCE VOLTAGE CHANGE
vs. LOAD CURRENT
MAX4036 toc29
LOAD CURRENT (µA)
NORMALIZED VREF
4003002001000
0.99
1.00
1.01
1.02
0.98
-100 500
TA = +85°C
TA = +25°C
TA = -40°C
REFERENCE VOLTAGE CHANGE
vs. SUPPLY VOLTAGE
MAX4036 toc30
VDD (V)
NORMALIZED VREF
3.33.02.1 2.4 2.7
0.9996
0.9997
0.9998
0.9999
1.0000
1.0001
1.0002
1.0003
0.9995
1.8 3.6
TA = +85°C
TA = +25°C
TA = -40°C
Typical Operating Characteristics (continued)
(VDD = 3V, VSS = VCM = 0V, RLto VDD/2, TA= +25°C, unless otherwise noted.)
REFERENCE LINE-TRANSIENT RESPONSE
MAX4036 toc31
1ms/div
VDD
VREF
AC-COUPLED
50mV/div
0V
1.8V
3.6V
MAX4036–MAX4039
Low IBIAS, +1.4V/800nA, Rail-to-Rail Op Amps
with +1.2V Buffered Reference
_______________________________________________________________________________________ 9
REFERENCE LOAD-TRANSIENT RESPONSE
(SINKING CURRENT)
MAX4036 toc32
2.5ms/div
0
VREF
500mV/div
0
2µA
IREF
MAX4036 toc33
2.5ms/div
0
0
20µA
IREF
VREF
500mV/div
REFERENCE LOAD-TRANSIENT RESPONSE
(SINKING CURRENT)
REFERENCE LOAD-TRANSIENT RESPONSE
(SOURCING CURRENT)
MAX4036 toc34
1ms/div
0
0
IREF
10µA
VREF
500mV/div
MAX4036 toc35
1ms/div
0
0
IREF
100µA
VREF
500mV/div
REFERENCE LOAD-TRANSIENT RESPONSE
(SOURCING CURRENT)
REFERENCE TURN-ON
TRANSIENT RESPONSE
MAX4036 toc36
1ms/div
VDD
0V
3V
0V
VREF
0.1Hz TO 10Hz REFERENCE NOISE
MAX4036 toc37
1s/div
20µV/div
Typical Operating Characteristics (continued)
(VDD = 3V, VSS = VCM = 0V, RLto VDD/2, TA= +25°C, unless otherwise noted.)
MAX4036–MAX4039
Low IBIAS, +1.4V/800nA, Rail-to-Rail Op Amps
with +1.2V Buffered Reference
10 ______________________________________________________________________________________
Detailed Description
The MAX4036–MAX4039 consume an ultra-low supply
current and have rail-to-rail output stages specifically
designed for low-voltage operation. The input common-
mode voltage range extends from VDD - 0.4V to VSS,
although full rail-to-rail input range is possible with
degraded performance when operating from a supply
voltage above 3.0V. The input offset voltage is typically
200µV. Low-operating supply voltage, low supply current,
and rail-to-rail outputs make the MAX4036–MAX4039 an
excellent choice for precision or general-purpose low-
voltage, battery-powered systems.
Rail-to-Rail Outputs
The MAX4036–MAX4039 output stages can drive a 5kΩ
load and still swing to within 40mV of the rails. Figure 1
shows the output voltage swing of the MAX4036–
MAX4039 configured as a unity-gain buffer, powered
from a single 2.4V supply. The output for this setup typi-
cally swings from 5mV to VDD - 5mV with a 100kΩload.
PIN
MAX4038/
MAX4038A MAX4039
MAX4036/
MAX4036A
MAX4037
µMAX*/TDFN UCSP
µMAX/TDF
UCSP
NAME FUNCTION
13———— IN+ Noninverting Amplifier Input
22 4A25A2 VSS Negative Power-Supply Voltage
34———— IN- Inverting Amplifier Input
41————OUT Amplifier Output
56 8C210C2V
DD Positive Power-Supply Voltage
—5 ——6B2REF Reference Voltage Output
—— 1C11 C1 OUTA Amplifier Output (Channel A)
—— 2B12 B1 INA- Inverting Amplifier Input (Channel A)
—— 3A13 A1 INA+ Noninverting Amplifier Input (Channel A)
—— 5A37 A3 INB+ Noninverting Amplifier Input (Channel B)
—— 6B38 B3 INB- Inverting Amplifier Input (Channel B)
—— 7C39 C3 OUTB Amplifier Output (Channel B)
—— —B24 —N.C. No Connection. Not internally connected.
—— ————EP
(TDFN only)
Exposed Paddle. Solder EP to VSS or leave
unconnected (TDFN packages only).
2ms/div
1V/div
VIN_+ 1.5V
1.5V
VOUT+
AV = 1V/V
Figure 1. Rail-to-Rail Input/Output Voltage Range
*Both MAX4038/MAX4038A available in µMAX package only.
MAX4036–MAX4039
Low IBIAS, +1.4V/800nA, Rail-to-Rail Op Amps
with +1.2V Buffered Reference
______________________________________________________________________________________ 11
Applications Information
Power-Supply Considerations
The MAX4036–MAX4039 operate from a single 1.4V
(MAX4036/MAX4038) or 1.8V (MAX4037/MAX4039) to
3.6V supply. A high amplifier power-supply rejection
ratio of 82dB and the excellent reference line regulation
allow the devices to be powered directly from a decay-
ing battery voltage, simplifying design and extending
battery life. The MAX4036–MAX4039 are ideally suited
for low-voltage battery-powered systems. The Typical
Operating Characteristics show the changes in supply
current and reference output as a function of supply
voltage.
Power-Up Settling Time
The MAX4036–MAX4039 typically require 0.25ms to
power-up. During this startup time, the output is inde-
terminate. The application circuit should allow for this
initial delay. See the Typical Operating Characteristics
for amplifier and reference settling time curves.
Driving Capacitive Loads: Op Amps
The MAX4036–MAX4039 amplifier(s) require no output
capacitor for stability, and are unity-gain stable for
loads up to 5000pF. Applications that require greater
capacitive-drive capability should use an isolation
resistor between the output and the capacitive load
(Figure 2). Note that this solution reduces the gain and
output voltage swing because RISO forms a voltage-
divider with the load resistor.
Crossover Distortion
The MAX4036–MAX4039 output stages are capable of
sourcing and sinking currents with orders of magnitude
greater than the stages’ quiescent current, which is
less than 1µA. This ability to drive heavy loads with
such a small quiescent current introduces crossover
distortion as the output stage passes between sinking
and sourcing. In the crossover regions, the output
impedance of the MAX4036–MAX4039 increases sub-
stantially, thereby changing the load-driving character-
istics. The distortion can be greatly reduced by
increasing the load resistance. For applications where
low load resistance is required, bias the load such that
the output current is always in one direction, to avoid
crossover distortion.
Reference Bypassing
The MAX4037/MAX4039 reference requires no external
capacitors.
Using the MAX4036–MAX4039 as a
Comparator
Although optimized for use as an operational amplifier,
the MAX4036–MAX4039 can be used as a rail-to-rail
I/O comparator (Figures 3, 4). External hysteresis can
be used to minimize the risk of output oscillation. The
positive feedback circuit, shown in Figure 4, causes the
input threshold to change when the output voltage
changes state.
Battery Monitoring Using the
MAX4037/MAX4039 and Hysteresis
The internal reference and low operating voltage of the
MAX4037/MAX4039 make the devices ideal for battery-
monitoring applications. Hysteresis can be set using
resistors as shown in Figure 4, and the following design
procedure:
1) Choose R3. The input bias current of IN_+ is under
100pA over temperature, so a current through R3
around 100nA maintains accuracy. The current
through R3 at the trip point is VREF / R3, or 100nA
for R3 = 12MΩ. 10MΩis a good practical value.
2) Choose the hysteresis voltage (VHB), the voltage
between the upper and lower thresholds. In this
example, choose VHB = 50mV (see Figure 3).
MAX4038
RISO
RLCL
RL
RL + RISO
AV = = 1
Figure 2. Using a Resistor to Isolate a Capacitive Load from
the Op Amp
VHB
VOH
VOL
VTHR
VTHF
INPUT
OUTPUT
Figure 3. Hysteresis
MAX4036–MAX4039
Low IBIAS, +1.4V/800nA, Rail-to-Rail Op Amps
with +1.2V Buffered Reference
12 ______________________________________________________________________________________
3) Calculate R1:
4) Choose the threshold voltage for VIN rising (VTHR).
In this example, choose VTHR = 2.0V.
5) Calculate R2:
6) Verify the threshold voltages with these formulas:
VIN rising:
VIN falling:
In this application, the MAX4036–MAX4039 supply cur-
rent will vary, depending on the output state of the
comparator.
Power Supplies and Layout
The MAX4036–MAX4039 operate from a single 1.4V
(MAX4036/MAX4038) or 1.8V (MAX4037/MAX4039) to
3.6V power supply. Bypass VDD with a 0.1µF capacitor
to ground to minimize noise.
Good layout techniques optimize performance by
decreasing the amount of stray capacitance to the op
amp’s inputs and outputs. To decrease stray capaci-
tance, minimize trace lengths by placing external com-
ponents close to the device.
The exposed paddle (EP) on the TDFN packages of the
MAX4038 and MAX4039 is internally connected to the
device substrate, VSS. Connect the exposed paddle to
VSS or leave EP unconnected. Running traces below the
exposed paddle is not recommended.
Chip Information
MAX4036 TRANSISTOR COUNT: 49
MAX4037 TRANSISTOR COUNT: 119
MAX4038 TRANSISTOR COUNT: 146
MAX4039 TRANSISTOR COUNT: 146
PROCESS: BiCMOS
VV RV
R
THF THR DD
=−×
⎛
⎝
⎜⎞
⎠
⎟
1
3
VVR
RR R
THR REF
=××++
⎛
⎝
⎜⎞
⎠
⎟
11
1
1
2
1
3
R
V
VRRR
V
Vk k M
k
THR
REF
21
1
1
1
1
3
1
20
1 2 210
1
210
1
10
325
.
.
=
×
⎛
⎝
⎜⎞
⎠
⎟−−
⎡
⎣
⎢
⎢
⎤
⎦
⎥
⎥
=
×
⎛
⎝
⎜⎞
⎠
⎟−−
⎡
⎣
⎢⎤
⎦
⎥
=
ΩΩΩ
Ω
RR V
V
MV
V
k
HB
DD
13
10 05
24
210
.
.
=×
=×
=
Ω
Ω
VREF
R3
R1
R2
VBATT
VBGOOD
VSS
VSS
VDD
VDD
IN+
REF
IN-
OUT
MAX4037
Figure 4. Battery Monitoring
Selector Guide
PART
NO. OF AMPLIFIERS
REFERENCE
MAX4036 1 —
MAX4037 1 √
MAX4038 2 —
MAX4039 2 √
Ordering Information (continued)
PART
TEMP RANGE
PIN-
PACKAGE
TOP
MARK
MAX4039EBL-T
-40°C to +85°C
9 UCSP-9
AEH
MAX4039ETB-T
-40°C to +85°C 10 TDFN-EP*
AAN
MAX4039EUB
-40°C to +85°C
10 µMAX —
*EP = Exposed paddle.
MAX4036–MAX4039
Low IBIAS, +1.4V/800nA, Rail-to-Rail Op Amps
with +1.2V Buffered Reference
______________________________________________________________________________________ 13
Pin Configurations
INB-
OUTB
INB+VSS
1
2
8
7
VDD
INA-
INA+
OUTA
µMAX
3
4
6
5
1
2
3
4
5
10
9
8
7
6
VDD
OUTB
INB-
INB+N.C.
INA+
INA-
OUTA
µMAX
REF
VSS
OUT
IN+
1
2
3
6
4IN-
VSS
VSS
VSS
VDD
VDD
VDD
SOT23
5REF
IN+
IN-
1
2
3
5
4OUT
VSS
VDD
SC70
TOP VIEW
OUTA
INA-
INA+
N.C.
OUTB
INB-
INB+
REF
3mm x 3mm x 0.8mm TDFN
OUTA
INA-
INA+
1
2
3
4
1
2
3
4
5
OUTB
INB-
INB+
8
7
6
5
8
7
6
9
10
3mm x 3mm x 0.8mm TDFN
MAX4036
MAX4036A
MAX4037
MAX4038
MAX4038A MAX4038
MAX4039 MAX4039
C
A
B
UCSP
MAX4038
INB+
VSS
INA+
INB-INA- N.C.
VDD OUTBOUTA
123
C
A
B
UCSP
MAX4039
INB+
VSS
INA+
INB-INA- REF
VDD OUTBOUTA
123
(BUMP SIDE DOWN)
TDFN EXPOSED PAD CONNECTED TO VSS.
TDFN EXPOSED PAD CONNECTED TO VSS.
(BUMP SIDE DOWN)
MAX4036–MAX4039
Low IBIAS, +1.4V/800nA, Rail-to-Rail Op Amps
with +1.2V Buffered Reference
14 ______________________________________________________________________________________
SC70, 5L.EPS
PACKAGE OUTLINE, 5L SC70
21-0076 1
1
C
Package Information
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information,
go to www.maxim-ic.com/packages.)
MAX4036–MAX4039
Low IBIAS, +1.4V/800nA, Rail-to-Rail Op Amps
with +1.2V Buffered Reference
______________________________________________________________________________________ 15
6LSOT.EPS
PACKAGE OUTLINE, SOT 6L BODY
21-0058 1
1
G
Package Information (continued)
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information,
go to www.maxim-ic.com/packages.)
MAX4036–MAX4039
Low IBIAS, +1.4V/800nA, Rail-to-Rail Op Amps
with +1.2V Buffered Reference
16 ______________________________________________________________________________________
8LUMAXD.EPS
PACKAGE OUTLINE, 8L uMAX/uSOP
1
1
21-0036
J
REV.DOCUMENT CONTROL NO.APPROVAL
PROPRIETARY INFORMATION
TITLE:
MAX
0.043
0.006
0.014
0.120
0.120
0.198
0.026
0.007
0.037
0.0207 BSC
0.0256 BSC
A2 A1
c
eb
A
L
FRONT VIEW SIDE VIEW
E H
0.6±0.1
0.6±0.1
Ø0.50±0.1
1
TOP VIEW
D
8
A2 0.030
BOTTOM VIEW
1
6°
S
b
L
H
E
D
e
c
0°
0.010
0.116
0.116
0.188
0.016
0.005
8
4X S
INCHES
-
A1
A
MIN
0.002
0.950.75
0.5250 BSC
0.25 0.36
2.95 3.05
2.95 3.05
4.78
0.41
0.65 BSC
5.03
0.66
6°0°
0.13 0.18
MAX
MIN
MILLIMETERS
-1.10
0.05 0.15
α
α
DIM
Package Information (continued)
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information,
go to www.maxim-ic.com/packages.)
MAX4036–MAX4039
Low IBIAS, +1.4V/800nA, Rail-to-Rail Op Amps
with +1.2V Buffered Reference
______________________________________________________________________________________ 17
6, 8, &10L, DFN THIN.EPS
L
CL
C
PIN 1
INDEX
AREA
D
E
L
e
L
A
e
E2
N
G
12
21-0137
PACKAGE OUTLINE, 6,8,10 & 14L,
TDFN, EXPOSED PAD, 3x3x0.80 mm
-DRAWING NOT TO SCALE-
k
e
[(N/2)-1] x e
REF.
PIN 1 ID
0.35x0.35
DETAIL A
b
D2
A2
A1
COMMON DIMENSIONS
SYMBOL MIN. MAX.
A0.70 0.80
D2.90 3.10
E2.90 3.10
A1 0.00 0.05
L0.20 0.40
PKG. CODE ND2 E2 eJEDEC SPEC b[(N/2)-1] x e
PACKAGE VARIATIONS
0.25 MIN.k
A2 0.20 REF.
2.30±0.101.50±0.106T633-1 0.95 BSC MO229 / WEEA 1.90 REF0.40±0.05
1.95 REF0.30±0.05
0.65 BSC
2.30±0.108T833-1
2.00 REF0.25±0.05
0.50 BSC
2.30±0.1010T1033-1
2.40 REF0.20±0.05- - - -
0.40 BSC
1.70±0.10 2.30±0.1014T1433-1
1.50±0.10
1.50±0.10
MO229 / WEEC
MO229 / WEED-3
0.40 BSC - - - - 0.20±0.05 2.40 REFT1433-2 14 2.30±0.101.70±0.10
T633-2 6 1.50±0.10 2.30±0.10 0.95 BSC MO229 / WEEA 0.40±0.05 1.90 REF
T833-2 8 1.50±0.10 2.30±0.10 0.65 BSC MO229 / WEEC 0.30±0.05 1.95 REF
T833-3 8 1.50±0.10 2.30±0.10 0.65 BSC MO229 / WEEC 0.30±0.05 1.95 REF
-DRAWING NOT TO SCALE-
G22
21-0137
PACKAGE OUTLINE, 6,8,10 & 14L,
TDFN, EXPOSED PAD, 3x3x0.80 mm
DOWNBONDS
ALLOWED
NO
NO
NO
NO
YES
NO
YES
NO
Package Information (continued)
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information,
go to www.maxim-ic.com/packages.)
MAX4036–MAX4039
Low IBIAS, +1.4V/800nA, Rail-to-Rail Op Amps
with +1.2V Buffered Reference
18 ______________________________________________________________________________________
10LUMAX.EPS
PACKAGE OUTLINE, 10L uMAX/uSOP
1
1
21-0061
REV.DOCUMENT CONTROL NO.APPROVAL
PROPRIETARY INFORMATION
TITLE:
TOP VIEW
FRONT VIEW
1
0.498 REF
0.0196 REF
S
6°
SIDE VIEW
α
BOTTOM VIEW
0° 0° 6°
0.037 REF
0.0078
MAX
0.006
0.043
0.118
0.120
0.199
0.0275
0.118
0.0106
0.120
0.0197 BSC
INCHES
1
10
L1
0.0035
0.007
e
c
b
0.187
0.0157
0.114
H
L
E2
DIM
0.116
0.114
0.116
0.002
D2
E1
A1
D1
MIN
-A
0.940 REF
0.500 BSC
0.090
0.177
4.75
2.89
0.40
0.200
0.270
5.05
0.70
3.00
MILLIMETERS
0.05
2.89
2.95
2.95
-
MIN
3.00
3.05
0.15
3.05
MAX
1.10
10
0.6±0.1
0.6±0.1
Ø0.50±0.1
H
4X S
e
D2
D1
b
A2 A
E2
E1 L
L1
c
α
GAGE PLANE
A2 0.030 0.037 0.75 0.95
A1
Package Information (continued)
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information,
go to www.maxim-ic.com/packages.)
MAX4036–MAX4039
Low IBIAS, +1.4V/800nA, Rail-to-Rail Op Amps
with +1.2V Buffered Reference
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________ 19
©2006 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products, Inc.
9LUCSP, 3x3.EPS
PACKAGE OUTLINE, 3x3 UCSP
21-0093
1
1
J
Package Information (continued)
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information,
go to www.maxim-ic.com/packages.)
ENGLISH • ???? • ??? • ???
WHAT'S NEW
PRODUCTS
SOLUTIONS
DESIGN
APPNOTES
SUPPORT
BUY
COMPANY
MEMBERS
MAX4038
Part Number Table
Notes:
See the MAX4038 QuickView Data Sheet for further information on this product family or download the
MAX4038 full data sheet (PDF, 540kB).
1.
Other options and links for purchasing parts are listed at: http://www.maxim-ic.com/sales.2.
Didn't Find What You Need? Ask our applications engineers. Expert assistance in finding parts, usually within
one business day.
3.
Part number suffixes: T or T&R = tape and reel; + = RoHS/lead-free; # = RoHS/lead-exempt. More: See full
data sheet or Part Naming Conventions.
4.
* Some packages have variations, listed on the drawing. "PkgCode/Variation" tells which variation the product
uses.
5.
Part Number
Free
Sample
Buy
Direct
Package:
TYPE PINS SIZE
DRAWING CODE/VAR *
Temp
RoHS/Lead-Free?
Materials Analysis
MAX4038ETA
THIN QFN (Dual);8 pin;3X3X0.8mm
Dwg: 21-0137I (PDF)
Use pkgcode/variation: T833-2*
-40C to +85C
RoHS/Lead-Free: No
Materials Analysis
MAX4038ETA+
THIN QFN (Dual);8 pin;3X3X0.8mm
Dwg: 21-0137I (PDF)
Use pkgcode/variation: T833+2*
-40C to +85C
RoHS/Lead-Free: Yes
Materials Analysis
MAX4038ETA-T
THIN QFN (Dual);8 pin;3X3X0.8mm
Dwg: 21-0137I (PDF)
Use pkgcode/variation: T833-2*
-40C to +85C
RoHS/Lead-Free: No
Materials Analysis
MAX4038ETA+T
THIN QFN (Dual);8 pin;3X3X0.8mm
Dwg: 21-0137I (PDF)
Use pkgcode/variation: T833+2*
-40C to +85C
RoHS/Lead-Free: Yes
Materials Analysis
MAX4038EBL
UC SP;9 pin;
Dwg: 21-0093L (PDF)
Use pkgcode/variation: B9-1*
-40C to +85C
RoHS/Lead-Free: No
Materials Analysis
MAX4038EBL+
UC SP;9 pin;
Dwg: 21-0093L (PDF)
Use pkgcode/variation: B9+1*
-40C to +85C
RoHS/Lead-Free: Yes
Materials Analysis
MAX4038EBL-T
UC SP;9 pin;
Dwg: 21-0093L (PDF)
Use pkgcode/variation: B9-1*
-40C to +85C
RoHS/Lead-Free: No
Materials Analysis
MAX4038EBL+T
UC SP;9 pin;
Dwg: 21-0093L (PDF)
Use pkgcode/variation: B9+1*
-40C to +85C
RoHS/Lead-Free: Yes
Materials Analysis
MAX4038AAUA+T
uMAX;8 pin;3 x 3mm
Dwg: 21-0036J (PDF)
Use pkgcode/variation: U8+1*
-40C to +125C
RoHS/Lead-Free: Yes
Materials Analysis
MAX4038AAUA+
uMAX;8 pin;3 x 3mm
Dwg: 21-0036J (PDF)
Use pkgcode/variation: U8+1*
-40C to +125C
RoHS/Lead-Free: Yes
Materials Analysis
MAX4038EUA
uMAX;8 pin;3 x 3mm
Dwg: 21-0036J (PDF)
Use pkgcode/variation: U8-1*
-40C to +85C
RoHS/Lead-Free: No
Materials Analysis
MAX4038EUA-T
uMAX;8 pin;3 x 3mm
Dwg: 21-0036J (PDF)
Use pkgcode/variation: U8-1*
-40C to +85C
RoHS/Lead-Free: No
Materials Analysis
MAX4038EUA+T
uMAX;8 pin;3 x 3mm
Dwg: 21-0036J (PDF)
Use pkgcode/variation: U8+1*
-40C to +85C
RoHS/Lead-Free: Yes
Materials Analysis
MAX4038EUA+
uMAX;8 pin;3 x 3mm
Dwg: 21-0036J (PDF)
Use pkgcode/variation: U8+1*
-40C to +85C
RoHS/Lead-Free: Yes
Materials Analysis
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