19-1343; Rev 3; 9/06
Single/Dual/Quad, +1.8V/10µA, SOT23,
Beyond-the-Rails Op Amps
Features
The MAX4240–MAX4244 family of micropower op amps
operate from a single +1.8V to +5.5V supply or dual
±0.9V to ±2.75V supplies and have Beyond-the-Rails™
inputs and rail-to-rail output capabilities. These amplifiers provide a 90kHz gain-bandwidth product while
using only 10µA of supply current per amplifier. The
MAX4241/MAX4243 have a low-power shutdown mode
that reduces supply current to less than 1µA and forces
the output into a high-impedance state. Although the
minimum operating voltage is specified at +1.8V, these
devices typically operate down to +1.5V. The combination of ultra-low-voltage operation, beyond-the-rails
inputs, rail-to-rail outputs, and ultra-low power consumption makes these devices ideal for any portable/
two-cell battery-powered system.
♦ Ultra-Low-Voltage Operation:
Guaranteed Down to +1.8V
Typical Operation to +1.5V
These amplifiers have an input common-mode range
that extends 200mV beyond each rail, and their outputs typically swing to within 9mV of the rails with a
100kΩ load. Beyond-the-rails input and rail-to-rail output characteristics allow the full power-supply voltage
to be used for signal range. The combination of low
input offset voltage, low input bias current, and high
open-loop gain makes them suitable for low-power/lowvoltage precision applications.
The MAX4240 is offered in a space-saving 5-pin
SOT23 package. All specifications are guaranteed
over the -40°C to +85°C extended temperature range.
♦ Unity-Gain Stable for Capacitive Loads up to 200pF
Applications
Two-Cell BatteryPowered Systems
Portable/Battery-Powered
Electronic Equipment
Digital Scales
Strain Gauges
Sensor Amplifiers
Cellular Phones
Notebook Computers
PDAs
♦ Ultra-Low Power Consumption:
10µA Supply Current per Amplifier
1µA Shutdown Mode (MAX4241/MAX4243)
Up to 200,000 Hours Operation from Two AA
Alkaline Cells
♦ Beyond-the-Rails Input Common-Mode Range
♦ Outputs Swing Rail-to-Rail
♦ No Phase Reversal for Overdriven Inputs
♦ 200µV Input Offset Voltage
♦ 90kHz Gain-Bandwidth Product
♦ Available in Space-Saving 5-Pin SOT23 and
8-Pin µMAX® Packages
Ordering Information
PART
TEMP RANGE
PINPACKAGE
TOP
MARK
MAX4240EUK-T
-40°C to +85°C
5 SOT23-5
ACCS
MAX4241EUA
-40°C to +85°C
8 µMAX
—
MAX4241ESA
-40°C to +85°C
8 SO
—
MAX4242EUA
-40°C to +85°C
8 µMAX
—
MAX4242ESA
-40°C to +85°C
8 SO
—
MAX4243EUB
-40°C to +85°C
10 µMAX
—
MAX4243ESD
-40°C to +85°C
14 SO
—
MAX4244ESD
-40°C to +85°C
14 SO
—
Pin Configurations
Selector Guide
PART
NO. OF
AMPS
SHUTDOWN
MAX4240
1
—
MAX4241
1
Yes
8-pin µMAX/SO
MAX4242
2
—
8-pin µMAX/SO
MAX4243
2
Yes
MAX4244
4
—
PIN-PACKAGE
5-pin SOT23
10-pin µMAX,
14-pin SO
14-pin SO
Beyond-the-Rails is a trademark and µMAX is a registered
trademark of Maxim Integrated Products, Inc.
TOP VIEW
OUT
1
VEE 2
IN+ 3
5
VCC
4
IN-
MAX4240
SOT23-5
Pin Configurations continued at end of data sheet.
________________________________________________________________ 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
MAX4240–MAX4244
General Description
MAX4240–MAX4244
Single/Dual/Quad, +1.8V/10µA, SOT23,
Beyond-the-Rails Op Amps
ABSOLUTE MAXIMUM RATINGS
Supply Voltage (VCC to VEE) ....................................................6V
All Other Pins ...................................(VCC + 0.3V) to (VEE - 0.3V)
Output Short-Circuit Duration (to VCC or VEE)............Continuous
Continuous Power Dissipation (TA = +70°C)
5-pin SOT23 (derate 7.1mW/°C above +70°C).............571mW
8-pin µMAX (derate 4.1mW/°C above +70°C) ..............330mW
8-pin SO (derate 5.88mW/°C above +70°C).................471mW
10-pin µMAX (derate 5.6mW/°C above +70°C) ............444mW
14-pin SO (derate 8.33mW/°C above +70°C)...............667mW
Operating Temperature Range ...........................-40°C to +85°C
Junction Temperature ......................................................+150°C
Storage Temperature Range .............................-65°C to +160°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
(VCC = +1.8V to +5.5V, VEE = 0, VCM = 0, VOUT = VCC / 2, RL = 100kΩ tied to VCC / 2, SHDN = VCC, TA = +25°C, unless
otherwise noted.) (Note 1)
PARAMETER
SYMBOL
Supply-Voltage Range
VCC
Inferred from PSRR test
Supply Current
per Amplifier
ICC
SHDN = VCC
ICC(SHDN)
SHDN = VEE
Shutdown Supply
Current (Note 2)
Input Offset Voltage
Input Bias Current
Input Offset Current
Differential Input
Resistance
Input Common-Mode
Voltage Range
VOS
CONDITIONS
(VEE - 0.2V) ≤ VCM ≤
(VCC + 0.2V)
MAX
UNITS
5.5
V
VCC = 1.8V
10
12
VCC = 5.0V
14
18
VCC = 1.8V
1.0
1.5
VCC = 5.0V
2.0
3.0
MAX4241ESA
±0.20
±0.75
MAX4242ESA/MAX4243ESD/
MAX4244ESD
±0.20
±0.88
MAX4240EUK/MAX424_EUA/
MAX4243EUB
±0.25
±1.40
(Note 3)
±2
±6
IOS
(Note 3)
±0.5
±1.5
RIN(DIFF)
VCM
µA
µA
mV
nA
nA
⎥ VIN+ - VIN-⎥ < 1.0V
45
MΩ
⎥ VIN+ - VIN-⎥ > 2.5V
4.4
kΩ
Inferred from the CMRR test
CMRR
VCC = 5.0V
2
TYP
1.8
IB
VCC = 1.8V
Common-Mode
Rejection Ratio
(Note 4)
MIN
VEE - 0.2
VCC + 0.2
MAX4241ESA
72
90
MAX4242ESA/MAX4243ESD/
MAX4244ESD
69
90
MAX4240EUK/MAX424_EUA/
MAX4243EUB
63
88
MAX4241ESA
74
94
MAX4242ESA/MAX4243ESD/
MAX4244ESD
74
94
MAX4240EUK/MAX424_EUA/
MAX4243EUB
69
90
_______________________________________________________________________________________
V
dB
Single/Dual/Quad, +1.8V/10µA, SOT23,
Beyond-the-Rails Op Amps
(VCC = +1.8V to +5.5V, VEE = 0, VCM = 0, VOUT = VCC / 2, RL = 100kΩ tied to VCC / 2, SHDN = VCC, TA = +25°C, unless
otherwise noted.) (Note 1)
PARAMETER
SYMBOL
Power-Supply
Rejection Ratio
PSRR
Large-Signal
Voltage Gain
AVOL
Output Voltage
Swing High
VOH
Output Voltage
Swing Low
VOL
Output Short-Circuit
Current
IOUT(SC)
Output Leakage
Current in Shutdown
(Notes 2, 5)
CONDITIONS
1.8V ≤ VCC ≤ 5.5V
(VEE + 0.2V) ≤ VOUT ≤
(VCC - 0.2V)
Specified as
⎥VCC - VOH⎥
Specified as
⎥VEE - VOL⎥
MIN
TYP
MAX4241ESA
77
85
MAX4242ESA/MAX4243ESD/
MAX4244ESD
77
85
MAX4240EUK/MAX424_EUA/
MAX4243EUB
75
82
RL = 100kΩ
76
85
RL = 10kΩ
66
73
RL = 100kΩ
86
94
RL = 10kΩ
78
85
VCC = 1.8V
VCC = 5.0V
VCC = 1.8V
VCC = 5.0V
VCC = 1.8V
VCC = 5.0V
MAX
dB
dB
RL = 100kΩ
8
20
RL = 10kΩ
40
65
RL = 100kΩ
10
25
RL = 10kΩ
60
95
RL = 100kΩ
6
15
RL = 10kΩ
23
35
RL = 100kΩ
10
20
40
60
RL = 10kΩ
Sourcing
0.7
Sinking
2.5
IOUT(SHDN) SHDN = VEE = 0, VCC = 5.5V
20
UNITS
mV
mV
mA
50
nA
SHDN Logic Low
(Note 2)
VIL
SHDN Logic High
(Note 2)
VIH
SHDN Input Bias
Current (Note 2)
IIH, IIL
SHDN = VCC = 5.5V or SHDN = VEE = 0
40
Channel-to-Channel
Isolation (Note 6)
CHISO
Specified at DC
80
dB
Gain-Bandwidth
Product
GBW
90
kHz
Phase Margin
Φm
68
degrees
Gain Margin
Gm
18
dB
Slew Rate
SR
40
V/ms
0.3 x VCC
0.7 x VCC
V
V
80
nA
_______________________________________________________________________________________
3
MAX4240–MAX4244
ELECTRICAL CHARACTERISTICS (continued)
Single/Dual/Quad, +1.8V/10µA, SOT23,
Beyond-the-Rails Op Amps
MAX4240–MAX424
ELECTRICAL CHARACTERISTICS (continued)
(VCC = +1.8V to +5.5V, VEE = 0, VCM = 0, VOUT = VCC / 2, RL = 100kΩ tied to VCC / 2, SHDN = VCC, TA = +25°C, unless
otherwise noted.) (Note 1)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Input Voltage-Noise
Density
en
f = 1kHz
70
nV/√Hz
Input Current-Noise
Density
in
f = 1kHz
0.05
pA/√Hz
AVCL = +1V/V, no sustained oscillations
200
pF
tSHDN
50
µs
tENABLE
150
µs
Power-Up Time
tON
200
µs
Input Capacitance
CIN
3
pF
Total Harmonic
Distortion
THD
0.05
%
50
µs
Capacitive-Load
Stability
Shutdown Time
Enable Time from
Shutdown
Settling Time to 0.01%
tS
fIN = 1kHz, VCC = 5.0V, VOUT = 2Vp-p, AV = +1V/V
AV = +1V/V, VCC = 5.0V, VOUT = 2VSTEP
ELECTRICAL CHARACTERISTICS
(VCC = +1.8V to +5.5V, VEE = 0, VCM = 0, VOUT = VCC / 2, RL = 100kΩ tied to VCC / 2, SHDN = VCC, TA = TMIN to TMAX, unless oth
erwise noted.) (Note 1)
PARAMETER
SYMBOL
Supply-Voltage Range
VCC
Supply Current
per Amplifier
Shutdown Supply
Current (Note 2)
Input Offset Voltage
Input Offset Voltage
Drift
Input Bias Current
CONDITIONS
Inferred from PSRR test
ICC
SHDN = VCC
ICC(SHDN)
SHDN = VEE
VOS
(VEE - 0.2V) ≤ VCM ≤
(VCC + 0.2V)
MIN
TYP
1.8
MAX
UNITS
5.5
V
VCC = 1.8V
14
VCC = 5.0V
19
VCC = 1.8V
2.0
VCC = 5.0V
3.5
MAX4241ESA
±1.2
MAX4242ESA/MAX4243ESD/
MAX4244ESD
±1.3
MAX4240EUK/MAX424_EUA/
MAX4243EUB
±2.0
TCVOS
2
µA
µA
mV
µV/°C
IB
(Note 3)
±15
nA
Input Offset Current
IOS
(Note 3)
±7
nA
Input Common-Mode
Voltage Range
VCM
Inferred from the CMRR test
4
-0.2
_______________________________________________________________________________________
VCC + 0.2
V
Single/Dual/Quad, +1.8V/10µA, SOT23,
Beyond-the-Rails Op Amps
(VCC = +1.8V to +5.5V, VEE = 0, VCM = 0, VOUT = VCC / 2, RL = 100kΩ tied to VCC / 2, SHDN = VCC, TA = TMIN to TMAX, unless oth
erwise noted.) (Note 1)
PARAMETER
SYMBOL
CONDITIONS
VCC = 1.8V
Common-Mode
Rejection Ratio
(Note 4)
CMRR
VCC = 5.0V
Power-Supply
Rejection Ratio
PSRR
Large-Signal
Voltage Gain
AVOL
Output Voltage
Swing High
VOH
Output Voltage
Swing Low
VOL
Output Leakage
Current in Shutdown
(Notes 2, 5)
SHDN Logic Low
(Note 2)
1.8V ≤ VCC ≤ 5.5V
(VEE + 0.2V) ≤ VOUT ≤
(VCC - 0.2V)
Specified as
⎥VCC - VOH⎥
Specified as
⎥VEE - VOL⎥
65
MAX4242ESA/MAX4243ESD/
MAX4244ESD
65
MAX4240EUK/MAX424_EUA/
MAX4243EUB
61
MAX4241ESA
71
MAX4242ESA/MAX4243ESD/
MAX4244ESD
71
MAX4240EUK/MAX424_EUA/
MAX4243EUB
67
MAX4241ESA
73
MAX4242ESA/MAX4243ESD/
MAX4244ESD
73
MAX4240EUK/MAX424_EUA/
MAX4243EUB
71
VCC = 1.8V
VCC = 5.0V
VCC = 1.8V
VCC = 5.0V
VCC = 1.8V
VCC = 5.0V
IOUT(SHDN) SHDN = VEE = 0, VCC = 5.5V
VIL
MIN
MAX4241ESA
RL = 100kΩ
72
RL = 10kΩ
62
RL = 100kΩ
80
RL = 10kΩ
72
TYP
MAX
UNITS
dB
dB
dB
RL = 100kΩ
25
RL = 10kΩ
95
RL = 100kΩ
30
RL = 10kΩ
145
RL = 100kΩ
20
RL = 10kΩ
50
RL = 100kΩ
25
RL = 10kΩ
75
100
0.3 x VCC
mV
mV
nA
V
_______________________________________________________________________________________
5
MAX4240–MAX4244
ELECTRICAL CHARACTERISTICS
ELECTRICAL CHARACTERISTICS (continued)
(VCC = +1.8V to +5.5V, VEE = 0, VCM = 0, VOUT = VCC / 2, RL = 100kΩ tied to VCC / 2, SHDN = VCC, TA = TMIN to TMAX, unless oth
erwise noted.) (Note 1)
PARAMETER
SYMBOL
SHDN Logic High
(Note 2)
VIH
SHDN Input Bias
Current (Note 2)
IIH, IIL
CONDITIONS
MIN
TYP
MAX
UNITS
0.7 x VCC
V
120
SHDN = VCC = 5.5V or SHDN = VEE = 0
nA
Note 1: The MAX4240EUK, MAX4241EUA, MAX4242EUA, and MAX4243EUB specifications are 100% tested at TA = +25°C. All
temperature limits are guaranteed by design.
Note 2: Shutdown mode applies to the MAX4241/MAX4243 only.
Note 3: Input bias current and input offset current are tested with VCC = +0.5V and +0.5V ≤ VCM ≤ +4.5V.
Note 4: Tested over the specified input common-mode range.
Note 5: Tested for 0 ≤ VOUT ≤ VCC. Does not include current through external feedback network.
Note 6: Channel-to-channel isolation specification applies to the MAX4242/MAX4243/MAX4244 only.
__________________________________________Typical Operating Characteristics
(VCC = +5.0V, VEE = 0, VCM = VCC / 2, V SHDN = VCC, RL = 100kΩ to VCC / 2, TA = +25°C, unless otherwise noted.)
VCC = +5.5V
14
12
10
VCC = +1.8V
8
6
4
1.8
4
1.6
1.5
3
VCC = +5.5V
2
1.4
1.3
VCC = +1.8V
1.2
1
1.1
2
0
0
-20
0
20
40
60
80
100
1.0
-60 -40
-20
0
20
40
60
80
100
-20
20
0
40
60
80
100
TEMPERATURE (°C)
INPUT OFFSET VOLTAGE
vs. TEMPERATURE
INPUT BIAS CURRENT
vs. TEMPERATURE
INPUT BIAS CURRENT vs.
COMMON-MODE VOLTAGE (VCC = 1.8V)
200
100
VCM = 0
VCC = +1.8V
-20
0
20
40
TEMPERATURE (°C)
60
80
100
VCC = +1.8V
2.5
-1
VCC = +5.5V
-2
-3
0
-2.5
-5.0
-4
0
5.0
MAX4240/44-06a
0
MAX4240/44-05
MAX4240/44-04
300
-40
-40
TEMPERATURE (°C)
400
-60
-60
TEMPERATURE (°C)
IBIAS (nA)
-40
INPUT BIAS CURRENT (nA)
-60
6
PSRR ≥ 80dB
1.7
VCC (V)
SUPPLY CURRENT (µA)
16
5
MINIMUM OPERATING VOLTAGE
vs. TEMPERATURE
MAX4240/44-02
18
SHUTDOWN SUPPLY CURRENT (µA)
MAX4240/44-01
20
SHUTDOWN SUPPLY CURRENT
PER AMPLIFIER vs. TEMPERATURE
MAX4240/44-03
SUPPLY CURRENT PER AMPLIFIER
vs. TEMPERATURE
INPUT OFFSET VOLTAGE (µV)
MAX4240–MAX4244
Single/Dual/Quad, +1.8V/10µA, SOT23,
Beyond-the-Rails Op Amps
-60
-40
-20
0
20
40
TEMPERATURE (°C)
60
80
100
-0.2
0.2
0.6
1.0
VCM (V)
_______________________________________________________________________________________
1.4
1.8
Single/Dual/Quad, +1.8V/10µA, SOT23,
Beyond-the-Rails Op Amps
0
-2.5
RL TO VEE
100
VCC = +1.8V, RL = 10kΩ
80
60
VCC = +5.5V, RL = 20kΩ
40
1.5
0.5
2.5
3.5
4.5
-60
-20
40
20
0
60
VCC = +1.8V, RL = 10kΩ
VCC = +5.5V, RL = 100kΩ
VCC = +1.8V, RL = 100kΩ
0
80
100
-60
-40
-20
20
0
40
60
100
COMMON-MODE REJECTION
vs. TEMPERATURE
OPEN-LOOP GAIN vs. OUTPUT SWING LOW
(VCC = +1.8V, RL TIED TO VEE)
OPEN-LOOP GAIN vs. OUTPUT SWING HIGH
(VCC = +1.8V, RL TIED TO VEE)
90
RL = 100kΩ
60
-20
0
20
40
60
80
70
60
50
50
40
40
30
-40
30
0
100
RL = 10kΩ
100
300
200
400
500
0
100
300
200
ΔVOUT (mV)
ΔVOUT (mV)
OPEN-LOOP GAIN vs. OUTPUT SWING LOW
(VCC = +5.5V, RL TIED TO VEE)
OPEN-LOOP GAIN vs. OUTPUT SWING HIGH
(VCC = +5.5V, RL TIED TO VEE)
OPEN-LOOP GAIN
vs. TEMPERATURE
RL = 100kΩ
100
110
MAX4240/44-13
RL = 100kΩ
90
110
MAX4240/44-12
110
105
GAIN (dB)
80
70
VCC = +5.5V, RL = 20kΩ TO VEE
100
90
RL = 20kΩ
RL = 20kΩ
80
70
500
400
TEMPERATURE (°C)
MAX4240/44-14
VCC = +5.5V
-95
70
GAIN (dB)
GAIN (dB)
VCC = +1.8V
-90
RL = 100kΩ
90
80
RL = 10kΩ
MAX4240/44-11
100
MAX4240/44-10
MAX4240/44-09
100
80
100
80
TEMPERATURE (°C)
-85
-60
VCC = +5.5V, RL = 20kΩ
40
TEMPERATURE (°C)
-100
GAIN (dB)
-40
60
VCM (V)
-80
COMMON-MODE REJECTION (dB)
5.5
80
20
VCC = +1.8V, RL = 100kΩ
0
-0.5
RL TO VCC
100
VCC = +5.5V, RL = 100kΩ
20
-5.0
120
MAX4240/44-08
120
GAIN (dB)
IBIAS (nA)
2.5
OUTPUT SWING LOW
vs. TEMPERATURE
MAX4240/44-07
VCC = +5.5V
VOLTAGE FROM VCC (mV)
MAX4240/44-06b
5.0
OUTPUT SWING HIGH
vs. TEMPERATURE
VOLTAGE FROM VEE (mV)
INPUT BIAS CURRENT vs.
COMMON-MODE VOLTAGE (VCC = 5.5V)
95
90
VCC = +5.5V, RL = 20kΩ TO VCC
85
60
60
50
50
75
40
40
70
0
100
200
ΔVOUT (mV)
300
400
VCC = +1.8V, RL = 10kΩ TO VEE
80
0
100
200
ΔVOUT (mV)
300
400
VCC = +1.8V, RL = 10kΩ TO VCC
-60
-40
-20
0
20
40
60
80
100
TEMPERATURE (°C)
_______________________________________________________________________________________
7
MAX4240–MAX4244
____________________________________Typical Operating Characteristics (continued)
(VCC = +5.0V, VEE = 0, VCM = VCC / 2, V SHDN = VCC, RL = 100kΩ to VCC / 2, TA = +25°C, unless otherwise noted.)
Typical Operating Characteristics (continued)
(VCC = +5.0V, VEE = 0, VCM = VCC/2, V SHDN = VCC, RL = 100kΩ to VCC/2, TA = +25°C unless otherwise noted.)
VCC = +1.8V, RL TO VEE
85
VCC = +1.8V, RL TO VCC
80
108
40
108
72
30
72
20
36
10
0
0
-10
-20
20
36
10
0
0
-36
-72
-10
-72
-108
-20
-108
-144
-36
-30
-144
-30
70
-40
-180
-40
-40
0
-20
20
40
60
80
100
10
100
1k
10k
1k
MAX4242/MAX4243/MAX4244
CROSSTALK vs. FREQUENCY
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. FREQUENCY
VOLTAGE NOISE
vs. FREQUENCY
0.1
-100
RL = 100k1
100
RL = 10k1
10
0.01
FREQUENCY (Hz)
FREQUENCY (Hz)
1
FREQUENCY (Hz)
LOAD RESISTOR vs.
CAPACITIVE LOAD
SMALL-SIGNAL TRANSIENT RESPONSE
(NONINVERTING)
SMALL-SIGNAL TRANSIENT RESPONSE
(INVERTING)
MAX4240/44-22
MAX4240/44-23
100
1
10k
1k
10
100
MAX4240/44-20
MAX4240/44-21
1000
10%
OVERSHOOT
REGION OF
MARGINAL STABILITY
100
0.1
1000
100mV
IN
IN
0V
0mV/div
0V
50mV/div
OUT
REGION OF
STABLE OPERATION
100mV
OUT
0V
0V
10
250
500
750
1000
10
100mV
100mV
10μs/div
CLOAD (pF)
8
100k
1000
VOLTAGE NOISE DENSITY (nV√Hz)
THD + NOISE (%)
-90
MAX4240/44-19
1
MAX4240/44-18
/
-80
0
10k
FREQUENCY (Hz)
-70
10
100
FREQUENCY (Hz)
RL = 10k1
-110
-180
10
100k
TEMPERATURE (°C)
-60
GAIN (dB)
40
30
75
-60
144
MAX4240 toc20
90
GAIN (dB)
GAIN (dB)
VCC = +5.5V, RL TO VCC
95
180
AV = +1000V/V
50
144
GAIN (dB)
VCC = +5.5V, RL TO VEE
50
MAX4240/44-17
60
180
AV = +1000V/V
PHASE (DEGREES)
105
MAX4240/44-16
60
MAX4240/44-15
110
100
GAIN AND PHASE vs. FREQUENCY
(CL = 100pF)
GAIN AND PHASE vs. FREQUENCY
(CL = 0pF)
PHASE (DEGREES)
OPEN-LOOP GAIN
vs. TEMPERATURE
RLOAD (k1)
MAX4240–MAX4244
Single/Dual/Quad, +1.8V/10µA, SOT23,
Beyond-the-Rails Op Amps
_______________________________________________________________________________________
10μs/div
Single/Dual/Quad, +1.8V/10µA, SOT23,
Beyond-the-Rails Op Amps
Pin Description
_______________________________________________________________________________________
9
MAX4240–MAX4244
Typical Operating Characteristics (continued)
(VCC = +5.0V, VEE = 0, VCM = VCC/2, V SHDN = VCC, RL = 100kΩ to VCC/2, TA = +25°C unless otherwise noted.)
Single/Dual/Quad, +1.8V/10µA, SOT23,
Beyond-the-Rails Op Amps
MAX4240–MAX424
_______________Detailed Description
Beyond-the-Rails Input Stage
The MAX4240–MAX4244 have Beyond-the-Rails inputs
and rail-to-rail output stages that are specifically
designed for low-voltage, single-supply operation. The
input stage consists of separate NPN and PNP differen
tial stages, which operate together to provide a com
mon-mode range extending to 200mV beyond both
supply rails. The crossover region of these two pairs
occurs halfway between VCC and VEE. The input offset
voltage is typically 200µV. Low operating supply voltage,
low supply current, beyond-the-rails common-mode
input range, and rail-to-rail outputs make this family of
operational amplifiers an excellent choice for precision or
general-purpose, low-voltage battery-powered systems.
Since the input stage consists of NPN and PNP pairs,
the input bias current changes polarity as the commonmode voltage passes through the crossover region.
Match the effective impedance seen by each input to
reduce the offset error caused by input bias currents
flowing through external source impedances (Figures
1a and 1b). The combination of high source impedance
plus input capacitance (amplifier input capacitance
plus stray capacitance) creates a parasitic pole that
produces an underdamped signal response. Reducing
input capacitance or placing a small capacitor across
the feedback resistor improves response in this case.
The MAX4240–MAX4244 family’s inputs are protected
from large differential input voltages by internal 2.2kΩ
series resistors and back-to-back triple-diode stacks
across the inputs (Figure 2). For differential input volt
ages (much less than 1.8V), input resistance is typically
45MΩ. For differential input voltages greater than 1.8V,
input resistance is around 4.4kΩ, and the input bias
current can be approximated by the following equation:
IBIAS = (VDIFF - 1.8V) / 4.4kΩ
MAX4240
MAX4241
MAX4242
MAX4243
MAX4244
VIN
R3
R3 = R1
R2
R1
R2
Figure 1a. Minimizing Offset Error Due to Input Bias Current
(Noninverting)
MAX4240
MAX4241
MAX4242
MAX4243
MAX4244
R3
R3 = R1
R2
VIN
R1
R2
Figure 1b. Minimizing Offset Error Due to Input Bias Current
(Inverting)
IN+
2.2k Ω
IN2.2kΩ
Figure 2. Input Protection Circuit
10
______________________________________________________________________________________
Single/Dual/Quad, +1.8V/10µA, SOT23,
Beyond-the-Rails Op Amps
MAX4240–MAX4244
In the region where the differential input voltage
approaches 1.8V, the input resistance decreases expo
nentially from 45MΩ to 4.4kΩ as the diode block begins
conducting. Conversely, the bias current increases with
the same curve.
MAX4240-44 fig03
RL = 100kΩ TIED TO VEE
VIN = 2.0V
fIN = 1kHz
1V/div
OUT
Rail-to-Rail Output Stage
The MAX4240–MAX4244 output stage can drive up to a
10kΩ load and still swing to within 40mV of the rails.
Figure 3 shows the output voltage swing of a MAX4240
configured as a unity-gain buffer, powered from a single
+2V supply voltage. The output for this setup typically
swings from (VEE + 6mV) to (VCC - 8mV) with a 100kΩ
load.
The MAX4240–MAX4244 operate from a single +1.8V
to +5.5V supply (or dual ±0.9V to ±2.75V supplies) and
consume only 10µA of supply current per amplifier. A
high power-supply rejection ratio of 85dB allows the
amplifiers to be powered directly off a decaying battery
voltage, simplifying design and extending battery life.
The MAX4240–MAX4244 are ideally suited for use with
most battery-powered systems. Table 1 lists a variety of
typical battery types showing voltage when fresh, volt
age at end-of-life, capacity, and approximate operating
time from a MAX4240/MAX4241, assuming nominal
conditions for both normal and shutdown modes.
Although the amplifiers are fully guaranteed over temperature for operation down to a +1.8V single supply,
even lower-voltage operation is possible in practice.
Figures 4 and 5 show the PSRR and supply current as
a function of supply voltage and temperature.
Figure 3. Rail-to-Rail Input/Output Voltage Range
100
MAX4240-44 fig04
Power-Supply Considerations
IN
200µs/div
TA = +85°C
90
PSRR (dB)
__________Applications Information
1V/div
80
TA = -40°C
70
TA = +25°C
60
1.0
1.2
1.4
1.6
1.8
2.0
SUPPLY VOLTAGE (V)
Figure 4. Power-Supply Rejection Ratio vs. Supply Voltage
Power-Up Settling Time
Shutdown Mode
The MAX4241 (single) and MAX4243 (dual) feature a
low-power shutdown mode. When the shutdown pin
(SHDN) is pulled low, the supply current drops to 1µA
per amplifier, the amplifier is disabled, and the outputs
enter a high-impedance state. Pulling SHDN high or
leaving it floating enables the amplifier. Take care to
ensure that parasitic leakage current at the SHDN pin
does not inadvertently place the part into shutdown
mode when SHDN is left floating. Figure 6 shows the
output voltage response to a shutdown pulse. The logic
threshold for SHDN is always referred to VCC / 2 (not to
MAX4240-44 fig05
12
10
SUPPLY CURRENT (µA)
The MAX4240–MAX4244 typically require 200µs to
power up after VCC is stable. During this start-up time,
the output is indeterminant. The application circuit
should allow for this initial delay.
8
TA = +85°C
6
4
TA = -40°C
TA = +25°C
2
0
1.0
1.2
1.4
1.6
1.8
2.0
SUPPLY VOLTAGE (V)
Figure 5. Supply Current vs. Supply Voltage
______________________________________________________________________________________
11
Table 1. MAX4240/MAX4241 Characteristics with Typical Battery Systems
RECHARGEABLE
VFRESH
(V)
VEND-OF-LIFE
(V)
CAPACITY,
AA SIZE
(mA-h)
MAX4240/MAX4241
OPERATING TIME
IN NORMAL MODE
(Hours)
MAX4241
OPERATING TIME
IN SHUTDOWN
MODE (Hours)
Alkaline (2 Cells)
No
3.0
1.8
2000
200,000
2 x 106
NickelCadmium (2 Cells)
Yes
2.4
1.8
750
75,000
0.75 x 106
Lithium-Ion (1 Cell)
Yes
3.5
2.7
1000
100,000
106
Nickel-MetalHydride (2 Cells)
Yes
2.4
1.8
1000
100,000
106
MAX4240-44 fig06
1200
VIN = 2V
RL = 100kΩ TIED TO VEE
5V/div
1V/div
OUTPUT SOURCE CURRENT (µA)
VCC = 5.5V, VOH = 200mV
SHDN
OUT
MAX4240-44 fig07a
BATTERY TYPE
1000
800
VCC = 1.8V,
VOH = 200mV
VCC = 5.5V, VOH = 100mV
600
VCC = 1.8V,
VOH = 100mV
400
200
VCC = 5.5V, VOH = 50mV
VCC = 1.8V, VOH = 50mV
0
-60 -40
200µs/div
-20
0
20
40
60
80
100
TEMPERATURE (°C)
Figure 7a. Output Source Current vs. Temperature
GND). When using dual supplies, pull SHDN to VEE to
enter shutdown mode.
3000
Load-Driving Capability
2500
The MAX4240–MAX4244 are fully guaranteed over tem
perature and supply voltage to drive a maximum resis
tive load of 10kΩ to VCC / 2, although heavier loads can
be driven in many applications. The rail-to-rail output
stage of the amplifier can be modeled as a current
source when driving the load toward VCC, and as a cur
rent sink when driving the load toward VEE. The magnitude of this current source/sink varies with supply
voltage, ambient temperature, and lot-to-lot variations
of the units.
Figures 7a and 7b show the typical current source and
sink capability of the MAX4240–MAX4244 family as a
function of supply voltage and ambient temperature.
The contours on the graph depict the output current
12
2000
MAX4240-44 fig07b
Figure 6. Shutdown Enable/Disable Output Voltage
OUTPUT SINK CURRENT (µA)
MAX4240–MAX4244
Single/Dual/Quad, +1.8V/10µA, SOT23,
Beyond-the-Rails Op Amps
VCC = 5.5V, VOL = 200mV
VCC = 1.8V, VOL = 200mV
VCC = 5.5V,
VOL = 100mV
1500
1000
500
VCC = 1.8V, VOL = 100mV
VCC = 5.5V, VOL = 50mV
VCC = 1.8V, VOL = 50mV
0
-60 -40
-20
0
20
40
60
80
TEMPERATURE (°C)
Figure 7b. Output Sink Current vs. Temperature
______________________________________________________________________________________
100
Single/Dual/Quad, +1.8V/10µA, SOT23,
Beyond-the-Rails Op Amps
RL =
1.8V - 0.1V
= 7kΩ to VEE
240µA
and VEE supplies should be bypassed to ground with
separate 100nF capacitors.
Good PC board layout techniques optimize perfor
mance by decreasing the amount of stray capacitance
at the op amp’s inputs and output. To decrease stray
capacitance, minimize trace lengths by placing exter
nal components as close as possible to the op amp.
Surface-mount components are an excellent choice.
The same application can drive a 3.3kΩ load resistor
when terminated in VCC / 2 (+0.9V in this case).
Driving Capacitive Loads
The MAX4240–MAX4244 are unity-gain stable for loads
up to 200pF (see Load Resistor vs. Capacitive Load
graph in Typical Operating Characteristics). Applica
tions that require greater capacitive drive capability
should use an isolation resistor between the output and
the capacitive load (Figure 8). Note that this alternative
results in a loss of gain accuracy because RISO forms a
voltage divider with the load resistor.
RISO
MAX4240
MAX4241
MAX4242
MAX4243
MAX4244
Power-Supply Bypassing and Layout
The MAX4240–MAX4244 family operates from either a
single +1.8V to +5.5V supply or dual ±0.9V to ±2.75V
supplies. For single-supply operation, bypass the
power supply with a 100nF capacitor to VEE (in this
case GND). For dual-supply operation, both the V CC
RL
CL
AV =
RL
≈1
R L + RISO
Figure 8a Using a Resistor to Isolate a Capacitive Load from
the Op Amp
MAX4240-44 fig08c
MAX4240-44 fig08b
50mV/div
IN
50mV/div
IN
50mV/div
OUT
50mV/div
OUT
100µs/div
RISO = NONE, RL = 100kΩ, CL = 700pF
Figure 8b. Pulse Response without Isolating Resistor
100µs/div
RISO = 1kΩ, RL = 100kΩ, CL = 700pF
Figure 8c. Pulse Response with Isolating Resistor
______________________________________________________________________________________
13
MAX4240–MAX4244
value, based on driving the output voltage to within
50mV, 100mV, and 200mV of either power-supply rail.
For example, a MAX4241 running from a single +1.8V
supply, operating at TA = +25°C, can source 240µA to
within 100mV of VCC and is capable of driving a 7kΩ
load resistor to VEE:
Using the MAX4240–MAX4244
as Comparators
Although optimized for use as operational amplifiers,
the MAX4240–MAX4244 can also be used as rail-to-rail
I/O comparators. Typical propagation delay depends
on the input overdrive voltage, as shown in Figure 9.
External hysteresis can be used to minimize the risk of
output oscillation. The positive feedback circuit, shown
in Figure 10, causes the input threshold to change
when the output voltage changes state. The two thresh
olds create a hysteresis band that can be calculated by
the following equations:
VHYST = VHI - VLO
VLO = VIN x R2 / (R1 + (R1 x R2 / RHYST) + R2)
V HI = [(R2 / R1 x V IN ) + (R2 / R HYST ) x V CC ] /
(1 + R1 / R2 + R2 / RHYST)
The MAX4240–MAX4244 contain special circuitry to
boost internal drive currents to the amplifier output
stage. This maximizes the output voltage range over
which the amplifiers are linear. In an open-loop com
parator application, the excursion of the output voltage
is so close to the supply rails that the output stage tran
sistors will saturate, causing the quiescent current to
increase from the normal 10µA. Typical quiescent cur
rents increase to 35µA for the output saturating at VCC
and 28µA for the output at VEE.
MAX4240-44 fig09
10,000
tPD+; VCC = +5V
1000
Using the MAX4240–MAX4244
as Ultra-Low-Power Current Monitors
The MAX4240–MAX4244 are ideal for applications
powered from a 2-cell battery stack. Figure 11 shows
an application circuit in which the MAX4240 is used for
monitoring the current of a 2-cell battery stack. In this
circuit, a current load is applied, and the voltage drop
at the battery terminal is sensed.
The voltage on the load side of the battery stack is
equal to the voltage at the emitter of Q1, due to the
feedback loop containing the op amp. As the load cur
rent increases, the voltage drop across R1 and R2
increases. Thus, R2 provides a fraction of the load cur
rent (set by the ratio of R1 and R2) that flows into the
emitter of the PNP transistor. Neglecting PNP base cur
rent, this current flows into R3, producing a ground-ref
erenced voltage proportional to the load current. Scale
R1 to give a voltage drop large enough in comparison
to VOS of the op amp, in order to minimize errors.
The output voltage of the application can be calculated
using the following equation:
VOUT = [ILOAD x (R1 / R2)] x R3
For a 1V output and a current load of 50mA, the choice
of resistors can be R1 = 2Ω, R2 = 100kΩ, R3 = 1MΩ.
The circuit consumes less power (but is more suscepti
ble to noise) with higher values of R1, R2, and R3.
INPUT
VOH
HYSTERESIS
VHI
VLO
VOH
OUTPUT
VOL
tPD (µs)
MAX4240–MAX4244
Single/Dual/Quad, +1.8V/10µA, SOT23,
Beyond-the-Rails Op Amps
tPD-; VCC = +5V
VIN
RHYST
R1
100
VCC
tPD+; VCC = +1.8V
VOUT
tPD-; VCC = +1.8V
10
0
10 20 30 40 50 60 70 80
90 100
VOD (mV)
R2
VEE
VEE
Figure 9. Propagation Delay vs. Input Overdrive
14
Figure 10. Hysteresis Comparator Circuit
______________________________________________________________________________________
MAX4240
MAX4241
MAX4242
MAX4243
MAX4244
Single/Dual/Quad, +1.8V/10µA, SOT23,
Beyond-the-Rails Op Amps
MAX4240/MAX4241
TRANSISTOR COUNT: 234
R1
VCC
MAX4242/MAX4243
TRANSISTOR COUNT: 466
R2
MAX4244
TRANSISTOR COUNT: 932
SUBSTRATE CONNECTED TO VEE
Q1
VOUT
R3
MAX4240
VEE
Figure 11. Current Monitor for a 2-Cell Battery Stack
_____________________________________________Pin Configurations (continued)
TOP VIEW
N.C. 1
IN- 2
8
SHDN
7
VCC
MAX4241
3
6
OUT
VEE 4
5
N.C.
IN+
OUTA 1
INA- 2
8
VCC
7
OUTB
OUTA 1
INA-
2
INA+
3
VEE
SHDNA
MAX4242
3
6
INB-
VEE 4
5
INB+
INA+
10 VCC
9
OUTB
8
INB-
4
7
INB+
5
6
SHDNB
MAX4243
µMAX
SO/µMAX
SO/µMAX
14 VCC
OUTA 1
INA-
2
INA+
3
VEE 4
MAX4243
N.C. 5
INA-
2
12 INB-
INA+
3
11 INB+
VCC 4
10 N.C.
INB+ 5
SHDNA 6
9
SHDNB
N.C. 7
8
N.C.
SO
14 OUTD
OUTA 1
13 OUTB
13 IND12 IND+
MAX4244
11 VEE
10 INC+
INB- 6
9
INC-
OUTB 7
8
OUTC
SO
______________________________________________________________________________________
15
MAX4240–MAX4244
___________________Chip Information
ILOAD
Tape-and-Reel Information
D
P0
W
P2
B0
t
D1
F
P
NOTE: DIMENSIONS ARE IN MM.
AND FOLLOW EIA481-1 STANDARD.
K0
A0
A0
3.200
±0.102
E
1.753
±0.102
P0
B0
3.099
±0.102
F
3.505
±0.051
P010
40.005
±0.203
D
1.499
+0.102
+0.000
K0
1.397
±0.102
P2
2.007
±0.051
3.988
±0.102
t
0.254
±0.127
0.991
+0.254
+0.000
P
D1
8.001
+0.305
-0.102
W
3.988
±0.102
5 SOT23-5
E
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.)
SOT-23 5L .EPS
MAX4240–MAX4244
Single/Dual/Quad, +1.8V/10µA, SOT23,
Beyond-the-Rails Op Amps
Revision History
Pages changed at Rev 3: 1, 8, 9, 16
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.
16 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2006 Maxim Integrated Products
is a registered trademark of Maxim Integrated Products. Inc.
工商网监
湘ICP备2023018690号
