MAXIM MAX4036|MAX4037|MAX4038|MAX4039

19-3142; Rev 0; 1/04
Low IBIAS, +1.4V/800nA, Rail-to-Rail Op Amps
with +1.2V Buffered Reference
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 reference. 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 reference 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 singlecell 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 µMAX and TDFN packages. All devices
are specified over the -40°C to +85°C extended temperature range.
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 5kΩ and 5000pF Load
♦ 1.232V ±0.5%, 80ppm/°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 SC70, SOT23, TDFN, and µMAX
Packages
Ordering Information
PART
TEMP RANGE
PINPACKAGE
Battery-Powered/Solar-Powered Systems
MAX4036EXK-T*
-40°C to +85°C
5 SC70-5
Portable Medical Instrumentation
MAX4037EUT-T
-40°C to +85°C
6 SOT23-6
ABRX
MAX4038ETA
-40°C to +85°C
8 TDFN-EP**
AGO
MAX4038EUA
-40°C to +85°C
8 µMAX
MAX4039ETB*
-40°C to +85°C
10 TDFN-EP**
MAX4039EUB
-40°C to +85°C
10 µMAX
Applications
Pagers and Cell Phones
Micropower Thermostats and Potentiostats
Electrometer Amplifiers
Remote Sensor Amplifiers
pH Meters
—
AAN
—
Pin Configurations and Selector Guide appear at end of
data sheet.
Rail-to-Rail is a registered trademark of Nippon Motorola, Ltd.
Functional Diagram
Typical Operating Circuit
3V
INAOUTA
VDD
MAX4039
VDD
OUTB
INA-
AFR
*Future product—contact factory for availability.
**EP = Exposed paddle.
Active Badges
OUTA
TOP
MARK
INA+
REF
SENSOR
MAX4039
INB-
INBINA+
INB+
REF
INB+
REF
OUTB
ADC
VSS
VSS
THREE-ELECTRODE POTENTIOSTAT APPLICATION
________________________________________________________________ Maxim Integrated Products
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.
1
MAX4036–MAX4039
General Description
MAX4036–MAX4039
Low IBIAS, +1.4V/800nA, Rail-to-Rail Op Amps
with +1.2V Buffered Reference
ABSOLUTE MAXIMUM RATINGS
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
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 ...........................-40°C to +85°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.
ELECTRICAL CHARACTERISTICS
(VDD = +3V, VSS = VCM = 0V, VOUT_ = VDD/2, RL to VDD/2, CL = 15pF, TA = +25°C, unless otherwise specified.)
PARAMETER
Supply Voltage Range
SYMBOL
VDD
CONDITIONS
TYP
MAX
MAX4036/MAX4038, guaranteed by PSRR
tests
1.4
3.6
MAX4037/MAX4039, guaranteed by PSRR
and line regulation tests
1.8
3.6
UNITS
V
MAX4036
MAX4037
Supply Current
MIN
IDD
MAX4038
MAX4039
VDD = 1.4V
0.8
1.2
VDD = 3.6V
0.9
1.3
VDD = 1.8V
1.9
2.4
VDD = 3.6V
2.0
2.5
VDD = 1.4V
1.7
2.3
VDD = 3.6V
1.9
2.5
VDD = 1.8V
2.8
4.0
VDD = 3.6V
3.0
4.1
µA
OPERATIONAL AMPLIFIERS
Input Offset Voltage
Input Bias Current
Input Offset Current
Input Common-Mode Voltage
Range
Common-Mode Rejection Ratio
Power-Supply Rejection Ratio
2
VOS
±0.2
±2.0
mV
IB
(Note 1)
±1.0
±10
pA
IOS
(Note 1)
±0.3
±20
pA
VCM
CMRR
PSRR
Guaranteed by
CMRR test
VDD = 1.4V
(MAX4036/MAX4038 only)
VSS
VDD 0.4
VDD = 1.8V
VSS
VDD 0.3
VDD = 3.3V
VSS
VDD 0.2
VDD = 1.4V, VSS † VCM † (VDD - 0.4V)
(MAX4036/MAX4038 only)
50
70
VDD = 1.8V, VSS † VCM † (VDD - 0.3V)
50
70
VDD = 3.3V, VSS † VCM † (VDD - 0.2V)
56
76
1.4V † VDD † 3.6V (MAX4036/MAX4038
only)
62
82
1.8V † VDD † 3.6V
62
84
_______________________________________________________________________________________
V
dB
dB
Low IBIAS, +1.4V/800nA, Rail-to-Rail Op Amps
with +1.2V Buffered Reference
(VDD = +3V, VSS = VCM = 0V, VOUT_ = VDD/2, RL to VDD/2, CL = 15pF, TA = +25°C, unless otherwise specified.)
PARAMETER
SYMBOL
Large-Signal Voltage Gain
AVOL
Output Voltage Swing High
VDD - VOH
Output Voltage Swing Low
VOL - VSS
Output Short-Circuit Current
ISCO
Gain-Bandwidth Product
GBW
MIN
TYP
RL = 100kΩ, 50mV † VOUT † (VDD - 50mV)
CONDITIONS
80
108
RL = 5kΩ, 150mV † VOUT † (VDD - 150mV)
78
105
MAX
dB
RL = 100kΩ
2
5
RL = 5kΩ
25
50
RL = 100kΩ
2
5
RL = 5kΩ
25
50
To VDD or VSS
UNITS
mV
mV
±13
mA
4
kHz
Phase Margin
θM
90
Degrees
Slew Rate
SR
0.4
V/ms
Power-On Time
tON
(Note 3)
0.25
ms
en
f = 1kHz
500
nV/√Hz
AVCL = 1V/V, no sustained oscillations
5000
pF
Input Noise-Voltage Density
Capacitive-Load Stability
CLOAD
REFERENCE (MAX4037/MAX4039)
Reference Voltage
VREF
Line Regulation
∆VREF/
∆VDD
Load Regulation
∆VREF/
∆ILOAD
Reference Output Voltage Noise
Output Short-Circuit Current
Capacitive-Load Stability Range
en
ISCR
CLOAD
1.226
1.232
VDD = +1.8V to +3.6V
1.238
V
0.3
%/V
0 † ILOAD † 100µA, sourcing
0.0015
-20µA † ILOAD † 0, sinking
0.0075
0.1Hz to 10Hz
60
Short to VDD
0.25
Short to VSS
1.9
(Note 1)
0
%/µA
µVP-P
mA
250
pF
ELECTRICAL CHARACTERISTICS
(VDD = +3V, VSS = VCM = 0V, VOUT_ = VDD/2, RL to VDD/2, CL = 15pF, TA = TMIN to TMAX, unless otherwise specified.) (Note 2)
PARAMETER
SYMBOL
CONDITIONS
MAX4036/MAX4038, guaranteed by PSRR
test
Supply Voltage Range
VDD
1.4
TYP
MAX
UNITS
3.6
V
MAX4037/MAX4039, guaranteed by PSRR
and line regulation tests
MAX4036
MAX4037
Supply Current
MIN
IDD
MAX4038
MAX4039
1.8
3.6
VDD = 1.4V
1.7
VDD = 3.6V
1.8
VDD = 1.8V
3.1
VDD = 3.6V
3.2
VDD = 1.4V
2.9
VDD = 3.6V
3.2
VDD = 1.8V
5.2
VDD = 3.6V
5.3
µA
_______________________________________________________________________________________
3
MAX4036–MAX4039
ELECTRICAL CHARACTERISTICS (continued)
MAX4036–MAX4039
Low IBIAS, +1.4V/800nA, Rail-to-Rail Op Amps
with +1.2V Buffered Reference
ELECTRICAL CHARACTERISTICS (continued)
(VDD = +3V, VSS = VCM = 0V, VOUT_ = VDD/2, RL to VDD/2, CL = 15pF, TA = TMIN to TMAX, unless otherwise specified.) (Note 2)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
±8
mV
OPERATIONAL AMPLIFIERS
Input Offset Voltage
VOS
Input Offset Voltage Temperature
Coefficient
±1
TCVOS
Input Bias Current
Input Offset Current
Input Common-Mode Voltage
Range
IB
±100
pA
IOS
±200
pA
VCM
Common-Mode Rejection Ratio
CMRR
Power-Supply Rejection Ratio
PSRR
Large-Signal Voltage Gain
µV/°C
AVOL
Output Voltage Swing High
VDD - VOH
Output Voltage Swing Low
VOL - VSS
Guaranteed by
CMRR test
VDD = 1.4V
(MAX4036/MAX4038 only)
VSS
VDD 0.4
VDD = 1.8V
VSS
VDD 0.4
VDD = 3.3V
VSS
VDD 0.2
VDD = 1.4V, VSS ≤ VCM ≤ (VDD - 0.4V)
(MAX4036/MAX4038 only)
44
VDD = 1.8V, VSS ≤ VCM ≤ (VDD - 0.4V)
50
VDD = 3.3V, VSS ≤ VCM ≤ (VDD - 0.2V)
52
1.4V ≤ VDD ≤ 3.6V
(MAX4036/MAX4038 only)
60
1.8V ≤ VDD ≤ 3.6V
60
RL = 100kΩ, 50mV ≤ VOUT ≤ (VDD - 50mV)
75
RL = 5kΩ, 150mV ≤ VOUT ≤ (VDD - 150mV)
73
V
dB
dB
dB
RL = 100kΩ
10
RL = 5kΩ
100
RL = 100kΩ
10
RL = 5kΩ
100
mV
mV
REFERENCE (MAX4037/MAX4039)
Reference Voltage Temperature
Coefficient
TCVREF
(Note 1)
Line Regulation
∆VREF/
∆VDD
VDD = 1.8V to 3.6V
Load Regulation
∆VREF/
∆ILOAD
0 ≤ ILOAD ≤ 100µA, sourcing
0.003
-20µA ≤ ILOAD ≤ 0, sinking
0.015
Capacitive-Load Stability Range
CLOAD
(Note 1)
20
0
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.
4
_______________________________________________________________________________________
80
ppm/°C
0.6
%/V
250
%/µA
pF
Low IBIAS, +1.4V/800nA, Rail-to-Rail Op Amps
with +1.2V Buffered Reference
TA = +25°C
0.8
TA = -40°C
0.4
TA = +25°C
2.5
2.0
1.5
TA = -40°C
1.0
3.0
0
1.4
1.8
2.2
2.6
3.4
3.0
1.5
1.0
TA = -40°C
0
1.8
2.1
2.4
2.7
3.0
3.3
3.6
1.4
1.8
2.2
2.6
SUPPLY VOLTAGE (V)
MAX4039
SUPPLY CURRENT
vs. SUPPLY VOLTAGE AND TEMPERATURE
OFFSET VOLTAGE
vs. COMMON-MODE VOLTAGE
OFFSET VOLTAGE
vs. TEMPERATURE
2
TA = -40°C
0.6
VDD = 1.8V
VDD = 3.0V
VDD = 1.4V
0.4
0.2
1
2.1
2.4
2.7
3.0
3.3
-0.10
1
-40
3
2
-15
10
35
60
85
SUPPLY VOLTAGE (V)
COMMON-MODE VOLTAGE (V)
TEMPERATURE (°C)
INPUT BIAS CURRENT
vs. TEMPERATURE
INPUT BIAS CURRENT
vs. COMMON-MODE VOLTAGE
OP AMP POWER-SUPPLY REJECTION RATIO
vs. FREQUENCY
20
VCM = 3V
10
0
-30
TA = +85°C
20
10
35
TEMPERATURE (°C)
-40
-50
-60
-70
10
-80
-90
VCM = 0V
-15
-20
30
TA = +25°C
-10
AV = 1V/V
-10
PSRR (dB)
INPUT BIAS CURRENT (pA)
30
0
MAX4036 toc09
40
MAX4036 toc07
40
-40
0
-0.30
0
3.6
MAX4036 toc08
1.8
0.10
-0.20
0
0
MAX4036 toc06
0.20
OFFSET VOLTAGE (mV)
3
0.30
MAX4036 toc05
0.8
OFFSET VOLTAGE (mV)
TA = +25°C
MAX4036 toc04
TA = +85°C
1.0
3.4
3.0
SUPPLY VOLTAGE (V)
4
SUPPLY CURRENT (µA)
2.0
SUPPLY VOLTAGE (V)
5
INPUT BIAS CURRENT (pA)
TA = +25°C
0.5
0.5
0
TA = +85°C
2.5
SUPPLY CURRENT (µA)
TA = +85°C
1.2
TA = +85°C
MAX4036 toc02
MAX4036 toc01
3.0
SUPPLY CURRENT (µA)
SUPPLY CURRENT (µA)
1.6
MAX4038
SUPPLY CURRENT
vs. SUPPLY VOLTAGE AND TEMPERATURE
MAX4037
SUPPLY CURRENT
vs. SUPPLY VOLTAGE AND TEMPERATURE
MAX4036 toc03
MAX4036
SUPPLY CURRENT
vs. SUPPLY VOLTAGE AND TEMPERATURE
0
60
85
-100
0
0.5
1.0
1.5
2.0
2.5
COMMON-MODE VOLTAGE (V)
3.0
10
100
1k
10k
FREQUENCY (Hz)
_______________________________________________________________________________________
5
MAX4036–MAX4039
Typical Operating Characteristics
(VDD = 3V, VSS = VCM = 0V, RL to VDD/2, TA = +25°C, unless otherwise noted.)
Typical Operating Characteristics (continued)
(VDD = 3V, VSS = VCM = 0V, RL to VDD/2, TA = +25°C, unless otherwise noted.)
VOL - VSS (mV)
RL = 5kΩ
100
AV (dB)
20
15
10
RL = 5kΩ
120
MAX4036 toc12
30
25
15
140
MAX4036 toc11
RL = 5kΩ
20
RL = 100kΩ
80
10
60
5
5
RL = 100kΩ
0
RL = 100kΩ
40
0
-15
10
35
85
60
-40
-15
10
35
60
0
85
100
200
300
400
TEMPERATURE (°C)
TEMPERATURE (°C)
VOL (mV)
AV
vs. OUTPUT SWING HIGH
AV
vs. TEMPERATURE
CROSSTALK
vs. FREQUENCY
140
MAX4036 toc13
140
RL = 5kΩ
120
0
120
500
MAX4036 toc15
-40
MAX4036 toc14
VDD - VOH (mV)
35
MAX4036 toc10
30
25
AV
vs. OUTPUT SWING LOW
OUTPUT VOLTAGE SWING LOW
vs. TEMPERATURE
OUTPUT VOLTAGE SWING HIGH
vs. TEMPERATURE
MAX4038/MAX4039
AV = 1V/V
-20
AV (dB)
AVOL (dB)
RL = 5kΩ
100
RL = 100kΩ
80
CROSSTALK (dB)
100
RL = 100kΩ
80
60
-40
RL = 5kΩ
-60
RL = 100kΩ
40
-80
60
20
0
0
100
200
300
400
500
-100
-40
-15
35
60
85
0
0.1
10k
1k
100k
TEMPERATURE (°C)
FREQUENCY (Hz)
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. FREQUENCY
OP AMP STABILITY
vs. CAPACITIVE AND RESISTIVE LOADS
OP AMP SINK CURRENT
vs. OUTPUT VOLTAGE
100,000
UNSTABLE
REGION
1
VOUT = 2.5VP-P
RL = 5kΩ TO VSS
0.1
10,000
1000
VOUT = 2.5VP-P
RL = 100kΩ TO VSS
STABLE
REGION
0.01
0.1
1
FREQUENCY (kHz)
10
100
VDD = 3.0V
10
8
6
VDD = 1.8V
4
2
RL TO VSS
0
100
0.01
VID = -100mV
12
SINK CURRENT (mA)
CAPACITIVE LOAD (pF)
10
14
MAX4036 toc17
AV = 1V/V
VIN_ = VDD/2
MAX4036 toc16
VDD - VOH (mV)
100
6
10
MAX4036 toc18
40
THD+N (%)
MAX4036–MAX4039
Low IBIAS, +1.4V/800nA, Rail-to-Rail Op Amps
with +1.2V Buffered Reference
10k
100k
RESISTIVE LOAD (Ω)
1M
0
0.6
1.2
1.8
VOUT_ (V)
_______________________________________________________________________________________
2.4
3.0
Low IBIAS, +1.4V/800nA, Rail-to-Rail Op Amps
with +1.2V Buffered Reference
OP AMP SOURCE CURRENT
vs. OUTPUT VOLTAGE
OP AMP VOLTAGE NOISE DENSITY
vs. FREQUENCY
100
VDD = 3.0V
12
NOISE (µV/√Hz)
SOURCE CURRENT (mA)
14
10
8
6
MAX4036 toc20
VID = +100mV
16
1000
MAX4036 toc19
18
VDD = 1.8V
10
1
4
2
0
0.1
0.6
1.2
1.8
2.4
3.0
10
1k
100
10k
FREQUENCY (Hz)
OP AMP
SMALL-SIGNAL TRANSIENT RESPONSE
OP AMP
SMALL-SIGNAL TRANSIENT RESPONSE
AV = 1V/V
CL = 12pF TO VSS
RL = 1MΩ TO VSS
2.55V
MAX4036 toc21
VOUT_ (V)
AV = 1V/V
CL = 250pF TO VSS
RL = 1MΩ TO VSS
2.55V
MAX4036 toc22
0
VIN+
VIN+
2.45V
2.45V
2.55V
2.55V
VOUT_
2.45V
VOUT_
2.45V
40µs/div
MAX4036 toc23
AV = 1V/V
CL = 12pF TO VSS
RL = 1MΩ TO VSS
2.5V
VIN+
1.5V
AV = 1V/V
CL = 12pF TO GND
RL = 1MΩ TO GND
VIN+ = VDD / 2
MAX4036 toc24
OP AMP
TURN-ON TRANSIENT RESPONSE
OP AMP
LARGE-SIGNAL TRANSIENT RESPONSE
3.0V
VDD
0V
VOUT_
500mV/div
100µs/div
VOUT_
50mV/div
100µs/div
________________________________________________________________________________________
7
MAX4036–MAX4039
Typical Operating Characteristics (continued)
(VDD = 3V, VSS = VCM = 0V, RL to VDD/2, TA = +25°C, unless otherwise noted.)
Typical Operating Characteristics (continued)
(VDD = 3V, VSS = VCM = 0V, RL to VDD/2, TA = +25°C, unless otherwise noted.)
GAIN AND PHASE
vs. FREQUENCY
GAIN
40
30
180
2
135
-2
90
-6
45
PHASE
0
-45
-40
1
10
100
1k
RL = 5kΩ
RL = 100kΩ
-22
AV = 1
VOUT_ = 1VP-P
CL = 12pF
-26
-135
100k
10k
RL = 1MΩ
-14
-18
-90
AV = 1000V/V
VIN_ = 1mVP-P
-10
-30
100
REFERENCE VOLTAGE CHANGE
vs. LOAD CURRENT
REFERENCE VOLTAGE CHANGE
vs. TIME
1.234
1.02
MAX4036 toc28
1.234
MAX4036 toc27
MAX4037/MAX4039
TA = +85°C
NORMALIZED VREF
VREF (V)
1.230
TA = +25°C
1.01
1.233
1.232
100k
FREQUENCY (Hz)
REFERENCE VOLTAGE
vs. TEMPERATURE
1.236
10k
1k
FREQUENCY (Hz)
MAX4037
1.232
MAX4039
MAX4036 toc29
20
10
0
-10
-20
-30
GAIN (dB)
GAIN (dB)
70
60
50
PHASE (DEGREES)
MAX4036 toc25
MAX4036 toc26
LARGE-SIGNAL GAIN
vs. FREQUENCY
80
VREF (V)
TA = -40°C
1.00
0.99
1.231
1.228
0.98
1.230
1.226
-15
10
35
60
0
85
100
200
300
400
500
-100
600
REFERENCE VOLTAGE CHANGE
vs. SUPPLY VOLTAGE
1.0002
100
REFERENCE LINE-TRANSIENT RESPONSE
MAX4036 toc30
1.0003
0
1.0001
3.6V
VDD
1.8V
1.0000
0.9999
0V
0.9998
TA = -40°C
VREF
AC-COUPLED
50mV/div
TA = +25°C
0.9997
TA = +85°C
0.9996
0.9995
1.8
2.1
2.4
2.7
3.0
3.3
3.6
1ms/div
VDD (V)
8
200
300
LOAD CURRENT (µA)
TIME (HR)
TEMPERATURE (°C)
MAX4036 toc31
-40
NORMALIZED VREF
MAX4036–MAX4039
Low IBIAS, +1.4V/800nA, Rail-to-Rail Op Amps
with +1.2V Buffered Reference
_______________________________________________________________________________________
400
500
Low IBIAS, +1.4V/800nA, Rail-to-Rail Op Amps
with +1.2V Buffered Reference
REFERENCE LOAD-TRANSIENT RESPONSE
(SINKING CURRENT)
REFERENCE LOAD-TRANSIENT RESPONSE
(SINKING CURRENT)
MAX4036 toc33
MAX4036 toc32
0
IREF
0
IREF
2µA
20µA
VREF
500mV/div
VREF
500mV/div
0
0
2.5ms/div
2.5ms/div
REFERENCE LOAD-TRANSIENT RESPONSE
(SOURCING CURRENT)
REFERENCE LOAD-TRANSIENT RESPONSE
(SOURCING CURRENT)
MAX4036 toc34
MAX4036 toc35
10µA
100µA
IREF
0
IREF
0
VREF
500mV/div
VREF
500mV/div
0
0
1ms/div
1ms/div
REFERENCE TURN-ON
TRANSIENT RESPONSE
0.1Hz TO 10Hz REFERENCE NOISE
MAX4036 toc36
MAX4036 toc37
3V
VDD
0V
VREF
0V
1ms/div
1s/div
20µV/div
_______________________________________________________________________________________
9
MAX4036–MAX4039
Typical Operating Characteristics (continued)
(VDD = 3V, VSS = VCM = 0V, RL to 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
Pin Description
PIN
MAX4036
NAME
FUNCTION
MAX4037
MAX4038
MAX4039
1
3
—
—
IN+
Noninverting Amplifier Input
2
2
4
5
VSS
Negative Power-Supply Voltage
3
4
—
—
IN-
Inverting Amplifier Input
4
1
—
—
OUT
Amplifier Output
5
6
8
10
VDD
Positive Power-Supply Voltage
—
5
—
6
REF
Reference Voltage Output
—
—
1
1
OUTA
—
—
2
2
INA-
Inverting Amplifier Input (Channel A)
—
—
3
3
INA+
Noninverting Amplifier Input (Channel A)
—
—
5
7
INB+
Noninverting Amplifier Input (Channel B)
—
—
6
8
INB-
Inverting Amplifier Input (Channel B)
—
—
7
9
OUTB
—
—
—
4
N.C.
—
—
—
—
Amplifier Output (Channel A)
Amplifier Output (Channel B)
No Connection. Not internally connected.
EP
Exposed Paddle. Solder EP to VSS or leave unconnected
(TDFN only) (TDFN packages only).
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 commonmode 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 lowvoltage, battery-powered systems.
AV = 1V/V
VIN_+
1.5V
VOUT+
1.5V
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 typically swings from 5mV to VDD - 5mV with a 100kΩ load.
10
2ms/div
1V/div
Figure 1. Rail-to-Rail Input/Output Voltage Range
______________________________________________________________________________________
Low IBIAS, +1.4V/800nA, Rail-to-Rail Op Amps
with +1.2V Buffered Reference
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 decaying 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 indeterminate. 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 voltagedivider 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
RISO
MAX4038
RL
AV =
CL
INPUT
VTHR
VHB
VTHF
VOH
OUTPUT
VOL
Figure 3. Hysteresis
distortion as the output stage passes between sinking
and sourcing. In the crossover regions, the output
impedance of the MAX4036–MAX4039 increases substantially, thereby changing the load-driving characteristics. 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 batterymonitoring 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. 10MΩ is 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).
RL
=1
RL + RISO
Figure 2. Using a Resistor to Isolate a Capacitive Load from
the Op Amp
______________________________________________________________________________________
11
MAX4036–MAX4039
Applications Information
MAX4036–MAX4039
Low IBIAS, +1.4V/800nA, Rail-to-Rail Op Amps
with +1.2V Buffered Reference
3)
Calculate R1:
VHB
VDD
0.5V
= 10MΩ ×
2.4 V
= 210kΩ
R3
R1 = R 3 ×
4)
5)
= 325kΩ
OUT
VSS
REF
VREF
 R1 × VDD 
VTHF = VTHR − 



R3
In this application, the MAX4036–MAX4039 supply current 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 capacitance, minimize trace lengths by placing external components 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.
MAX4037
VSS
Figure 4. Battery Monitoring
Selector Guide
PART
VIN falling:
VBGOOD
IN-
Verify the threshold voltages with these formulas:
VIN rising:
1
1 
 1
VTHR = VREF × R1 × 
+
+

 R1
R2
R3 
12
IN+
R2
1
 VTHR 
1
1 

 − R1 − R 3 
V
R
1
×

 REF

1
=

2.0V
1
1 

−
 −


210kΩ
10MΩ 
 1.2V × 210kΩ 
6)
VBATT
Choose the threshold voltage for VIN rising (VTHR).
In this example, choose VTHR = 2.0V.
Calculate R2:
R2 =
VDD
VDD
R1
NO. OF AMPLIFIERS
REFERENCE
MAX4036
1
—
MAX4037
1
√
MAX4038
2
—
MAX4039
2
√
Chip Information
MAX4036 TRANSISTOR COUNT: 49
MAX4037 TRANSISTOR COUNT: 119
MAX4038 TRANSISTOR COUNT: 146
MAX4039 TRANSISTOR COUNT: 146
PROCESS: BiCMOS
______________________________________________________________________________________
Low IBIAS, +1.4V/800nA, Rail-to-Rail Op Amps
with +1.2V Buffered Reference
TOP VIEW
IN+ 1
VSS 2
5 VDD
OUT 1
MAX4036
VSS 2
4 OUT
IN- 3
4 IN-
8 VDD
OUTA 1
7 OUTB
INA- 2
INA+ 3
6 INB-
INA+ 3
VSS 4
5 INB+
VSS 4
MAX4038
7 OUTB
MAX4038
6 INB5 INB+
3mm x 3mm x 0.8mm TDFN
µMAX
OUTA 1
5 REF
SOT23
8 VDD
INA- 2
MAX4037
IN+ 3
SC70
OUTA 1
6 VDD
10 VDD
OUTA 1
10 VDD
9 OUTB
9 OUTB
INA- 2
8 INB-
INA+ 3
4
7 INB+
N.C. 4
7 INB+
5
6 REF
VSS 5
6 REF
INA-
2
INA+
3
N.C.
VSS
MAX4039
MAX4039
8 INB-
3mm x 3mm x 0.8mm TDFN
µMAX
TDFN EXPOSED PAD CONNECTED TO VSS.
______________________________________________________________________________________
13
MAX4036–MAX4039
Pin Configurations
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.)
SC70 5L EPS
MAX4036–MAX4039
Low IBIAS, +1.4V/800nA, Rail-to-Rail Op Amps
with +1.2V Buffered Reference
14
______________________________________________________________________________________
Low IBIAS, +1.4V/800nA, Rail-to-Rail Op Amps
with +1.2V Buffered Reference
6LSOT.EPS
PACKAGE OUTLINE, SOT-23, 6L
21-0058
F
1
______________________________________________________________________________________
1
15
MAX4036–MAX4039
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.)
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.)
4X S
8
E
ÿ 0.50±0.1
8
INCHES
DIM
A
A1
A2
b
H
c
D
e
E
H
0.6±0.1
1
L
1
α
0.6±0.1
S
BOTTOM VIEW
D
MIN
0.002
0.030
MAX
0.043
0.006
0.037
0.014
0.010
0.007
0.005
0.120
0.116
0.0256 BSC
0.120
0.116
0.198
0.188
0.026
0.016
6∞
0∞
0.0207 BSC
8LUMAXD.EPS
MAX4036–MAX4039
Low IBIAS, +1.4V/800nA, Rail-to-Rail Op Amps
with +1.2V Buffered Reference
MILLIMETERS
MAX
MIN
0.05
0.75
1.10
0.15
0.95
0.25
0.36
0.13
0.18
2.95
3.05
0.65 BSC
2.95
3.05
4.78
5.03
0.41
0.66
0∞
6∞
0.5250 BSC
TOP VIEW
A1
A2
e
FRONT VIEW
A
c
b
α
L
SIDE VIEW
PROPRIETARY INFORMATION
TITLE:
PACKAGE OUTLINE, 8L uMAX/uSOP
APPROVAL
DOCUMENT CONTROL NO.
21-0036
16
______________________________________________________________________________________
REV.
J
1
1
Low IBIAS, +1.4V/800nA, Rail-to-Rail Op Amps
with +1.2V Buffered Reference
6, 8, &10L, DFN THIN.EPS
L
A
D
D2
A2
PIN 1 ID
1
N
1
C0.35
b
E
PIN 1
INDEX
AREA
[(N/2)-1] x e
REF.
E2
DETAIL A
e
k
A1
CL
CL
L
L
e
e
A
DALLAS
SEMICONDUCTOR
PROPRIETARY INFORMATION
TITLE:
PACKAGE OUTLINE, 6, 8 & 10L,
TDFN, EXPOSED PAD, 3x3x0.80 mm
NUMBER OF LEADS SHOWN ARE FOR REFERENCE ONLY
APPROVAL
DOCUMENT CONTROL NO.
21-0137
REV.
D
1
2
COMMON DIMENSIONS
SYMBOL
A
MIN.
MAX.
0.70
0.80
D
2.90
3.10
E
2.90
3.10
A1
0.00
0.05
L
k
0.20
0.40
0.25 MIN.
A2
0.20 REF.
PACKAGE VARIATIONS
PKG. CODE
N
D2
E2
e
JEDEC SPEC
b
T633-1
6
1.50±0.10
2.30±0.10
0.95 BSC
MO229 / WEEA
0.40±0.05
1.90 REF
T833-1
8
1.50±0.10
2.30±0.10
0.65 BSC
MO229 / WEEC
0.30±0.05
1.95 REF
T1033-1
10
1.50±0.10
2.30±0.10
0.50 BSC
MO229 / WEED-3
0.25±0.05
2.00 REF
[(N/2)-1] x e
DALLAS
SEMICONDUCTOR
PROPRIETARY INFORMATION
TITLE:
PACKAGE OUTLINE, 6, 8 & 10L,
TDFN, EXPOSED PAD, 3x3x0.80 mm
APPROVAL
DOCUMENT CONTROL NO.
21-0137
REV.
D
2
2
______________________________________________________________________________________
17
MAX4036–MAX4039
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.)
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.)
e
10LUMAX.EPS
MAX4036–MAX4039
Low IBIAS, +1.4V/800nA, Rail-to-Rail Op Amps
with +1.2V Buffered Reference
4X S
10
INCHES
10
H
ÿ 0.50±0.1
0.6±0.1
1
1
0.6±0.1
BOTTOM VIEW
TOP VIEW
D2
MILLIMETERS
MAX
DIM MIN
A
0.043
A1
0.002
0.006
A2
0.030
0.037
D1
0.116
0.120
D2
0.114
0.118
E1
0.116
0.120
0.118
E2
0.114
0.199
H
0.187
L
0.0157 0.0275
L1
0.037 REF
b
0.007
0.0106
e
0.0197 BSC
c
0.0035 0.0078
0.0196 REF
S
α
0∞
6∞
MAX
MIN
1.10
0.15
0.05
0.75
0.95
3.05
2.95
3.00
2.89
2.95
3.05
2.89
3.00
4.75
5.05
0.40
0.70
0.940 REF
0.177
0.270
0.500 BSC
0.090
0.200
0.498 REF
0∞
6∞
E2
GAGE PLANE
A2
c
A
b
D1
A1
α
E1
L
L1
FRONT VIEW
SIDE VIEW
PROPRIETARY INFORMATION
TITLE:
PACKAGE OUTLINE, 10L uMAX/uSOP
APPROVAL
DOCUMENT CONTROL NO.
21-0061
REV.
I
1
1
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.
18 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2004 Maxim Integrated Products
Printed USA
is a registered trademark of Maxim Integrated Products.