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19-1343; Rev 3; 9/06
Single/Dual/Quad, +1.8V/10µA, SOT23,
Beyond-the-Rails Op Amps
General Description
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 90kH z 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 pow er consumption makes these devices ideal for any portable/
two-cell battery-powered system.
These amplifiers have an input common-mode range
that extends 200mV beyond each rail, and their outputs typically sw ing to within 9mV of the rails with a
100kload. Beyond-the-rails input and rail-to-rail output characteristics allow the full power-supply voltage
M
Features
A
X
Guaranteed Down to +1.8V
Typical Operation to +1.5V
4
2
4
0
♦ Ultra-Low Power Consumption:
10µA Supply Current per Amplifier
M
♦ Beyond-the-Rails Input Common-Mode Range
A
X
4
2
4
4
♦ No Phase Reversal for Overdriven Inputs
♦ 200µV Input Offset Voltage
♦ Unity-Gain Stable for Capacitive Loads up to 200pF
♦ 90kHz Gain-Bandwidth Product
♦ Available in Space-Saving 5-Pin SOT23 and
®
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 M AX4240 is of fered in a sp ace-s aving 5-pin
SOT23 pack ag e. All sp ecificat ions are guaranteed
over the -40°C to +85°C extended temperature range.
Applications
Two-Cell BatteryPowered Systems
Portable/Battery-Powered
Electronic Equipment
Digital Scales
Strain Gauges
Sensor Amplifiers
Cellular Phones
Notebook Computers
PDAs
PART
TEMP RANGE
PIN-
MAX4240EUK-T
-40°C to +85°C
5 SOT23-5
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
TOP
ACCS
—
—
—
—
—
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
TOP VIEW
PART
NO. OF
AMPS
MAX4240
1
—
MAX4241
1
Yes
8-pin µMAX/SO
MAX4242
2
—
8-pin µMAX/SO
MAX4243
2
Yes
MAX4244
4
—
SHUTDOWN
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.
OUT 1
VEE 2
5 VCC
MAX4240
IN+ 3
4 IN-
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
–
Beyond-the-Rails Op Amps
4
4
2
4
ABSOLUTE MAXIMUM RATINGS
All Other Pins ...................................(VCC + 0.3V) to (VEE - 0.3V)
Continuous Power Dissipation (TA = +70°C)
5-pin SOT23 (derate 7.1mW/°C above +70°C).............571mW
X 8-pin µMAX (derate 4.1mW/°C above +70°C) ..............330mW
A 8-pin SO (derate 5.88mW/°C above +70°C).................471mW
M
–
0
14-pin SO (derate 8.33mW/°C above +70°C)...............667mW
Junction Temperature......................................................+150°C
Storage Temperature Range .............................-65°C to +160°C
Lead Temperature (soldering, 10s) .................................+300°C
Single/Dual/Quad, +1.8V/10µA, SOT23,
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
ELECTRICAL CHARACTERISTICS
4
2 (V
= +1.8V to +5.5V, V
= 0, V
= 0, V
= V
/ 2, R = 100k tied to V
/ 2, SHDN = V , T = +25°C, unless
Supply
otherwise
Voltage
noted.)
(V(Note
to 1)
V ) ....................................................6V
10-pin µMAX (derate 5.6mW/°C above +70°C) ............444mW

4
MIN
TYP to +85°C
MAX
Short-Circuit Duration SYMBOL
(to V
or V )............Continuous CONDITIONS
Operating Temperature Range ...........................-40°C
X OutputPARAMETER
UNITS
A
Supply-Voltage Range
V
Inferred from PSRR test
I
M
Shutdown Supply
Current (Note 2)
I
1.8
V
SHDN = V
5.5
= 1.8V
VCC = 5.0V
V
= 1.8V
SHDN = V
10
12
14
1.0
18
1.5
±0.20
±0.75
V
µA
µA
CC
MAX4241ESA
MAX4242ESA/MAX4243ESD/
Input Offset Voltage
EE
V
(V
CM
±0.20
±0.88
±0.25
±1.40
±2
±6
±0.5
45
±1.5
nA
M
+ 0.2
V
+ 0.2V)
MAX4240EUK/MAX424_EUA/
mV
MAX4243EUB
Input Bias Current
Input Offset Current
Resistance
Input Common-Mode
IB
(Note 3)
IOS
(Note 3)
- V < 1.0V
R
IN+
V
nA
IN-
Inferred from the CMRR test
V
- 0.2
V
Voltage Range
MAX4241ESA
MAX4242ESA/MAX4243ESD/
CC
Rejection Ratio
MAX4244ESD
MAX4240EUK/MAX424_EUA/
MAX4243EUB
MAX4241ESA
CMRR
(Note 4)
MAX4242ESA/MAX4243ESD/
MAX4244ESD
72
90
69
90
63
88
74
94
74
94
69
90
CC
MAX4240EUK/MAX424_EUA/
MAX4243EUB
2
_______________________________________________________________________________________
dB
Single/Dual/Quad, +1.8V/10µA, SOT23,
Beyond-the-Rails Op Amps
M
ELECTRICAL CHARACTERISTICS (continued)
A
(VCC = +1.8V to +5.5V, VEE = 0, VCM = 0, VOUT = VCC / 2, RL = 100ktied to VCC / 2, SHDN = VCC, TA = +25°C, unless
otherwise noted.) (Note 1)
PARAMETER
SYMBOL
CONDITIONS
MAX4241ESA
Power-Supply
Rejection Ratio
Large-Signal
Voltage Gain
PSRR
AVOL
1.8V VCC 5.5V
(VEE + 0.2V) VOUT 
(VCC - 0.2V)
MAX4242ESA/MAX4243ES
D/
MAX4244ESD
MAX4240EUK/MAX424_EU
A/
MAX4243EUB
RL = 100k
VCC = 1.8V
RL = 10k
RL = 100k
VCC = 5.0V
RL = 10k
VCC = 1.8V
Output Voltage
Swing High
Output Voltage
Swing Low
V
Specified as
- V 
CC
V
OH
Specified as
EE
- V OL
VCC = 5.0V
VCC = 1.8V
VCC = 5.0V
Output Short-Circuit
Current
IOUT(SC)
Output Leakage
Current in Shutdown
(Notes 2, 5)
IOUT(SHDN)
MIN
TYP
77
85
77
85
75
82
76
66
85
73
86
94
78
85
MAX
dB
A
8
20
40
65
RL = 100k
10
25
RL = 10k
RL = 100k
60
6
95
15
RL = 10k
23
35
RL = 100k
10
20
RL = 10k
40
60
0.7
2.5
SHDN = VEE = 0, VCC = 5.5V
20
X
4
2
4
4
dB
RL = 10k
Sinking
X
4
2
4
0
M
RL = 100k
Sourcing
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
m
68
degrees
Gain Margin
Gm
18
dB
Slew Rate
SR
40
V/ms
0.3 x
VCC
V
V
0.7 x VCC
80
_______________________________________________________________________________________
nA
–
3
Single/Dual/Quad, +1.8V/10µA, SOT23,
Beyond-the-Rails Op Amps
ELECTRICAL CHARACTERISTICS (continued)
(V
4
2
4
= +1.8V to +5.5V, V
= 0, V
CC
EE
otherwise noted.) (Note 1)
PARAMETER
= 0, V
CM
= V
OUT
/ 2, R = 100k tied to V

CC
SYMBOL
L
, T = +25°C, unless
/ 2, SHDN = V
CC
CONDITIONS
CC
MIN
A
TYP
MAX
UNITS
Input Voltage-Noise
Density
en
f = 1kHz
70
nV/Hz
A
M
–
0
4
2
4
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
X
Power-Up Time
tON
200
µs
A
Input Capacitance
CIN
3
pF
0.05
%
50
µs
X
Capacitive-Load
Stability
Shutdown Time
Enable Time from
Shutdown
Total Harmonic
THD
M Distortion
Settling Time to 0.01%
fIN = 1kHz, VCC = 5.0V, VOUT = 2Vp-p, AV = +1V/V
tS
AV = +1V/V, VCC = 5.0V, VOUT = 2VSTEP
ELECTRICAL CHARACTERISTICS
(V
= +1.8V to +5.5V, V
CC
= 0, V
EE
= 0, V
CM
erwisePARAMETER
noted.) (Note 1)
SYMBOL
Supply-Voltage Range
VCC
/ 2, SHDN = V
CC
Inferred from PSRR test
ICC
I
SHDN = VCC
SHDN = V
VOS
EE
(VEE - 0.2V) VCM 
(VCC + 0.2V)
Input Offset Voltage
Drift
L
CONDITIONS
CC(SHDN)
Input Offset Voltage
/ 2, R = 100ktied to V
CC
,T =T
CC
MIN
A
to T
MIN
TYP
1.8
, unless othMAX
MAX
5.5
UNITS
V
14
VCC = 1.8V
Supply Current
per Amplifier
Shutdown Supply
Current (Note 2)
=V
OUT
VCC = 5.0V
19
VCC = 1.8V
2.0
VCC = 5.0V
MAX4241ESA
±1.2
3.5
MAX4242ESA/MAX4243ES
D/
MAX4244ESD
MAX4240EUK/MAX424_EU
A/
MAX4243EUB
±1.3
µA
µA
mV
±2.0
2
TCVOS
µV/°C
Input Bias Current
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
M
ELECTRICAL CHARACTERISTICS
A
X
(VCC = +1.8V to +5.5V, VEE = 0, VCM = 0, VOUT = VCC / 2, RL = 100ktied to VCC / 2, SHDN = VCC, TA = TMIN to TMAX, unless otherwise noted.) (Note 1)
PARAMETER
UNITS
SYMBOL
CONDITIONS
MAX4241ESA
MAX4242ESA/MAX4243ES
D/
MAX4244ESD
MAX4240EUK/MAX424_EU
A/
MAX4243EUB
MAX4241ESA
VCC = 1.8V
Common-Mode
Rejection
(Note 4) Ratio
CMRR
MAX4242ESA/MAX4243ES
D/
MAX4244ESD
MAX4240EUK/MAX424_EU
A/
MAX4243EUB
MAX4241ESA
VCC = 5.0V
Power-Supply
PSRR
1.8V VCC 5.5V
Rejection Ratio
Large-Signal
Voltage Gain
AVOL
(VEE + 0.2V) VOUT 
(VCC - 0.2V)
MAX4242ESA/MAX4243ES
D/
MAX4244ESD
MAX4240EUK/MAX424_EU
A/
MAX4243EUB
RL = 100k
VCC = 1.8V
VCC = 5.0V
Output Voltage
Swing High
VCC = 1.8V
Specified as
VOH
CC

OH
-V

VCC = 5.0V
Output Voltage
Swing Low
VOL
Specified as
EE - VOL
VCC = 1.8V
VCC = 5.0V
Output Leakage
Current in Shutdown
(Notes 2, 5)
SHDN Logic Low
(Note 2)
IOUT(SHDN)
VIL
MIN
SHDN = VEE = 0, VCC = 5.5V
TYP
4
2
4
0
MAX
65
65
61
M
71
A
X
dB
71
4
2
4
4
67
73
73
dB
71
72
RL = 10k
62
RL = 100k
80
RL = 10k
72
dB
RL = 100k
25
RL = 10k
95
RL = 100k
30
RL = 10k
145
RL = 100k
20
RL = 10k
50
RL = 100k
25
RL = 10k
75
100
0.3 x VCC
_______________________________________________________________________________________
mV
–
mV
nA
V
5
Beyond-the-Rails Op Amps
4
4
2
4
X
ELECTRICAL CHARACTERISTICS (continued)
(VCC = +1.8V to +5.5V, VEE = 0, VCM = 0, VOUT = VCC / 2, RL = 100ktied to VCC / 2, SHDN = VCC, TA = TMIN to MAX, unless othT
erwise noted.) (Note 1)
PARAMETER
SYMBOL
SHDN Logic High
(Note 2)
CONDITIONS
MIN
VIH
TYP
MAX
UNITS
V
0.7 x VCC
Single/Dual/Quad, +1.8V/10µA, SOT23,
A
SHDN Input Bias
IIH, IIL
SHDN = VCC = 5.5V or SHDN = VEE = 0
M Current (Note 2)
–
0 Note 1: The MAX4240EUK, MAX4241EUA, MAX4242EUA, and MAX4243EUB specifications are 100% tested at T
temperature limits are guaranteed by design.
4
120
nA
= +25°C. All
2 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 V
V . Does not include current through external feedback network.
X Note 6: Channel-to-channel isolation specification applies to the MAX4242/MAX4243/MAX4244 only.
A
__________________________________________Typical Operating
M
Characteristics
(VCC = +5.0V, VEE = 0, VCM = VCC / 2, VSHDN = VCC, RL = 100kto VCC / 2, TA = +25°C, unless otherwise noted.)
SUPPLY CURRENT PER AMPLIFIER
vs. TEMPERATURE
OPERATING
VOLTAGE
TEMPERATURE
1
20
16
CC
V CC = +1.8V
-4 2
442X
5
-4
4 )
24X
4 
42X
T
R
R
U
Y
)L
U
SN
3
A
14
N 12
R
V 310
C
P
P
U
S 6
SHUTDOWN SUPPLY CURRENT
PER AMPLIFIER vs. TEMPERATURE
1.8
PSRR 80dB
4
C
V
1.4
= +1.8V
2
1.1
0
0
-60
60
400
6
-
1.6
CC
U
S
MINIMUM
vs.
-40
80
-20
0
20
40
60
100
TEMPERATURE (°C)
80
O
T 200
F
F
O
T
-60
-40
-20
0
20
40
1.0
80
60
100
-60
TEMPERATURE (°C)
vs. TEMPERATURE
INPUT
CC OFFSET VOLTAGE
vs.
300
100
V
V
=0
0
-4
4
a
V
= +1.8V
24
2.5
A
( nS
IB
I
-2.5
IN
-4
0
-60 -40 -20 0
20
40
60
TEMPERATURE (°C)
80
100
-5.0
-60 -40 -20
0
20
40
60
80 10
0
-0.2
0.2
TEMPERATURE (°C)
0.6
1.0
VC (V)
M
6
20
40
TEMPERATURE (°C)
M
= +1.8V
-20
COMMON-MODE VOLTAGE (V
INPUT BIAS CURRENT
5.0 = 1.8V)
0
INPUT BIAS CURRENT
50
/440
X
0/4A )
X
A A
(T
N
E
R
C -2
A
U
P
N -3
-40
_______________________________________________________________________________________
1.4
1.8
Single/Dual/Quad, +1.8V/10µA, SOT23,
Beyond-the-Rails Op Amps
M
____________________________________Typical Operating Characteristics (continued)
A
X
(VCC = +5.0V, VEE = 0, VCM = VCC / 2, VSHDN = VCC, RL = 100kto VCC / 2, TA = +25°C, unless otherwise noted.)
5.0
8
INPUT BIAS CURRENT vs.
COMMON-MODE
VOLTAGE (V = 5.5V)
LOW
TEMPERATURE
120
0b
OUTPUT SWING HIGH
vs. TEMPERATURE
44
-24
X
100
4A )V
m
(
C 80
C
M
O
R 60
O
60
T
O
V
CC
2.5
V
A
B
L
EE
V = +1.8V, R =
10k
7
44
MA
M
120
L
M
E 80
CC
CC
-5.0
0.5
1.5
80 100
2.5
3.5
4.5
5.5
-60
VCM (V)
100
11
A
)B
(X
A
N
-85
O
100k
T
E
R
( -90
M
N
O
M
-95
C
0
20
40
60
4
2
4
4
L
0
100
80
-60
-40
-20
0
20
40
TEMPERATURE (°C)
(VCC = +1.8V, RL TIED TOEE
V )
CC
EEOPEN-LOOP GAIN vs. OUTPUT
100 LOW
10 SWING
/
0
4
2
4X
A
90
R =
L
OPEN-LOOP GAIN vs.
0
4
4
R = 100k2
90
80
80
L
V
dB 70
B
A
(I
G
A
= +1.8V
CC
R = 10k
d
I
G
50
50
40
40
-100
30
-60
400
4
-20
CC
TEMPERATURE (°C)
COMMON-MODE REJECTION
09-4
OUTPUT SWING HIGH
110
20
= +1.8V, R = 100k
-40
L
V = +5.5V, R =
100k
0
-0.5
60
A
X
L
V = +5.5V, R =
100k
V
CC
100
F
G
T
O
V = +5.5V, R =
20k
20
4
2
4
0
OUTPUT SWING
vs.
-40
-20
500
0
20
40
60
80
100
0
(V = +5.5V, R TIED TO V )
TEMPERATURE
TEMPERATURE (°C)
(V
142
/41 LOW
OPEN-LOOP GAIN vs. OUTPUT SWING
4
100
X
OPEN-LOOP
R =GAIN
100k
44
X
90
R = 20k
B 80
(N
I
100
200
300
30
500
400
0
= +5.5V, R TIED TO V )
VOUT (mV)
3
110
/44
L
OPEN-LOOP
GAIN vs. OUTPUT
SWING
HIGH
4
105
X
M
V
V
M 100
)B
(N
R = 20kB
100
vs.
VOUT (mV)
/
= +5.5V, R = 20kTO
CC
L
CC
V CC= +1.8V, LR =
10kTO V
G5070
300
95
(
IN
60
G5070
200
EE
G
85
80
V (mV)
TEMPERATURE (°C)
V
(mV)
VCC = +1.8V, RL = 10kTO VCC
40
40
0
80
100
100
200
300
400
0
100
200
300
70
400
-60
-40
-20
0
20
OUT
_______________________________________________________________________________________
7
40
60
Beyond-the-Rails Op Amps
Typical Operating Characteristics (continued)
4
4 (VCC = +5.0V, VEE = 0, VCM = VCC/2, VSHDN = VCC, RL = 100k to VCC/2, TA = +25°C unless otherwise noted.)
2
4
OPEN-LOOP GAIN
GAIN AND PHASE vs. FREQUENCY

Single/Dual/Quad, +1.8V/10µA, SOT23,
GAIN AND PHASE vs. FREQUENCY
L
X
110
A
100
0
95
(
)B
4N
2 A
G
VC = +5.5V, RL
C TO V
M
EE
C
vs. TEMPERATURE
90
VC =100pF)
+1.8V, RL
C TO V
85
EE
VC = +1.8V, RL CC
C TO V
80
75
A
70
M
0
20
40
60
80
40
108
30
72
20
36
36
E
-10
-72
-20
-108
D (
R
G ) 10
BG
0
)H
( N-10
E A
A -20
-30
-144
-30
-180
-40
0
-36
1
0
10
0
1k
10k
(C =
0
-36
-72
-108
FREQUENCY (Hz)
TOTAL HARMONIC DISTORTION PLUS
NOISE
)SP
(
E
A
10
0
1
10k
k
FREQUENCY (Hz)
100k
VOLTAGE NOISE
vs. FREQUENCY
1000
/
X
840
2
D
R
G
-180
10
X
A
4
)
A
0
ct
4
vs. FREQUENCY
) -80
d
N
G -90
A
E
-144
100k
A
-70
50
72
100
MAX4242/MAX4243/MAX4244
CROSSTALK vs. FREQUENCY
RL = 10k
144
MAX4240/44-17
180
AV = +1000V/V 144
30
TEMPERATURE (°C)
-60
60
108
-40
-60 -40 -20
180
40
540
2X ( 20
)d
A 10
N 0
VC = +5.5V, RLTO VCC
4
X
AV = +1000V/V
50
105
M
–
MAX4240/44-16
60
-49
0
2
1
)%
E
IO
N
+T 0.1
D
100
O
-100
RL =
100k
-110
10
100
1k
0.0
1 1
10k
FREQUENCY (Hz)
10
1
100
0
FREQUENCY (Hz)
1000
MAX4240/44-2
2
10%
OVERSHOOT
100mV
A
IN
REGION OF
MARGINAL
STABILITY
0.1
1000
SMALL-SIGNAL TRANSIENT
RESPONSE
(NONINVERTING)
LOAD RESISTOR vs.
CAPACITIVE LOAD
)
(D
O
R
RL = 10k
zH

V
(
Y
I
N
D
E
I
N
E
G
T
1
FREQUENCY (Hz)
SMALL-SIGNAL TRANSIENT
RESPONSE
(INVERTING)
MAX4240/44-2
3
100mV
IN
0V
0mV/div
0V
50mV/div
100mV
04/
04X
A
REGION OF
STABLE
OPERATION
OUT
100mV
OUT
0V
0V
10
0
250
C
500
(pF)
75
0
1000
1
0
10s/div
10s/div
LOAD
8
_______________________________________________________________________________________
Beyond-the-Rails Op Amps
M
Typical Operating Characteristics (continued)
(V
CC
= +5.0V, V
= 0, V
EE
A
= V /2, V
= V , R = 100k to V +1.8V/10µA,
/2, T = +25°C unless otherwise
noted.)
Single/Dual/Quad,
SOT23,

CM
CC
SHDN
CC
L
CC
A
X
4
2
4
0
M
A
X
4
2
4
4
Pin Description
–
_______________________________________________________________________________________
9
Beyond-the-Rails Op Amps
_______________Detailed Description
4
2
4
Beyond-the-Rails Input Stage
The MAX4240–MAX4244 have Beyond-the-Rails inputs
and rail-to-rai l output stages that are specifically
designed for low-voltage, single-supply operation. The
X input stage consists of separate NPN and PNP differenA tial stages, which operate together to provide a comM mon-mode range extending to 200mV beyond b oth
MAX4240
MAX4241
MAX4242
MAX4243
MAX4244
Single/Dual/Quad, +1.8V/10µA, SOT23,
–
CC
EE
0 voltage is typically 200µV. Low operating supply voltage,
4 low supply current, beyond-the-rails common-mode
input range, and rail-to-rail outputs make this family of
4 operational amplifiers an excellent choice for precision or
general-purpose, low-voltage battery-powered systems.
X
Since the input stage consists of NPN and PNP pairs,
Athe input bias current changes polarity as the commone passes impedance
through theseen
crossover
Match voltag
the effective
by eachregion.
input to
M mode
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 2.2k
series resistors and back-to-back triple-diode stacks
across the inputs (Figure 2). For differential input voltages (much less than 1.8V), input resistance is typically
45M. For differential input voltages greater than 1.8V,
input resistance is around 4.4k, and the input bias
current can be approximated by the following equation:
IBIAS = (VDIFF - 1.8V) / 4.4k
R3
R3 = R1 R2
R1
R2
V
Figure 1a. Minimizing Offset Error Due to Input Bias Current
(Noninverting)
MAX4240
MAX4241
MAX4242
MAX4243
R3
R3 = R1
R2
VIN
R1
R2
Figure 1b. Minimizing Offset Error Due to Input Bias Current
(Inverting)
IN+
2.2k
MAX4244
IN2.2k
Figure 2. Input Protection Circuit
10
______________________________________________________________________________________
Single/Dual/Quad, +1.8V/10µA, SOT23,
Beyond-the-Rails Op Amps
M
In the region w here t he d if ferent ial input voltag e
approaches 1.8V, the input resistance decreases exponentially from 45Mto 4.4k as the diode block begins
conducting. Conversely, the bias current increases with
the same curve.
MAX4240-44 fig03

A
X
RILN= 1 20.00kTIED TO VEE
1V/div
fIN = 1kHz
OUT
Rail-to-Rail Output Stage
The MAX4240–MAX4244 output stage can drive up to a
10k 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 (V + 6mV) to (V
- 8mV) with a
100k
load.

__________Applications Information
1V/div
IN
200s/div
Figure 3. Rail-to-Rail Input/Output Voltage Range
Power-Supply Considerations
4
fg
40
24
M
100
A
high pow er-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
perature 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.
90
S
)
d
R
R
T = -40°C
70
A
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
The MAX4240–MAX4244 typically require 200µs to
power up after V
is stable. During this start-up time,
12
)

Shutdown Mode
(SHDN) is pulled low, the supply current drops to 1µA
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 p lace 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
M
A
X
The MAX4240–MAX4244 operate from a single +1.8V
most battery-powered systems. Table 1 lists a variety of
typical battery types showing voltage when fresh, voltage at end-of-life, capacity, and approximate operating
tim e from a MAX4240/MAX4241, assuming nom inal
conditions for both normal and shutdown modes.
Although the amplifiers are fully guaranteed over tem-
4
2
4
0
R
U
C
Y
L
S
g
4 f4
0
2
4
X
M
8
T = +85°C
4
T = -40°C
T = +25°C
2
0
Figure 5. Supply Current vs. Supply Voltage
______________________________________________________________________________________
11
4
2
4
4
Beyond-the-Rails Op Amps
4
4
2
4
Table 1. MAX4240/MAX4241 Characteristics with Typical Battery Systems
BATTERY TYPE
RECHARGEABLE
VFRESH
(V)
VEND-OF-LIFE
(V)
CAPACITY,
AA SIZE
(mA-h)
X
A
M
–
0
4
2
4
MAX4240/MAX4241
OPERATING TIME
IN NORMAL MODE
(Hours)
Alkaline (2 Cells)
No
3.0
1.8
2000
Single/Dual/Quad,
+1.8V/10µA,
SOT23,
Nickel-
MAX4241
OPERATING TIME
IN SHUTDOWN
MODE (Hours)
200,000
2 x 106
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
Cadmium (2 Cells)
X
MAX4240-44 fig06
A
1200
VIN = 2V
RL = 100kTIED TO
VEE
M
VC = 5.5V, O = 200mV
V
H
)
4
C
A
SHDN
5V/div
OUT
A
1000
T
N
S800
R
U
C
E
400
C 600
U
O
O200
T
U
T
U
1V/div
= 1.8V,
VO = 200mV
VC = 5.5V, O = 100mV
C V
H
H
= 1.8V,
V
C
VC = 100mV
O
H
V
a4
0
i4
-
= 50mV
VC = 5.5V,
C VOH
= 50mV
V = 1.8V, V
C
C
0
200s/div
-60 -40 -20
Figure 6. Shutdown Enable/Disable Output Voltage
GND). When using dual supplies, pull SHDN to V
enter shutdown mode.
OH
40
60
80
20
TEMPERATURE (°C)
100
Figure 7a. Output Source Current vs. Temperature
EE to
3000
V
Load-Driving Capability
The MAX4240–MAX4244 are fully guaranteed over temperature and supply voltage to drive a maximum resistive load of 10k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 current sink when driving the load toward VEE. The magnitude of this current source/sink varies with sup ply
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 tem perature.
The contours on the graph depict the output current
12
0
) 2500
= 5.5V, V
CC
= 200mV
OL
4
X
2M
VC = 1.8V, O =
L 200mV
C V
= 5.5V,
VO = 100mV
L
O
= 100mV
500

T
N
E
R 0
U
C
N1500
S
T
U
P
U
VC = 5.5V,
C VOL
b0
i4
-
VC = 1.8V,
C VOL
= 50mV
= 50mV
VC = 1.8V,
C VOL
-60 -40 -20 0
20 40 60 80 100
V
TEMPERATURE (°C)
Figure 7b. Output Sink Current vs. Temperature
______________________________________________________________________________________
Single/Dual/Quad, +1.8V/10µA, SOT23,
Beyond-the-Rails Op Amps
M
value, based on driving the output voltage to within
and VEE supplies should be bypassed to ground with
50mV, 100mV, and 200mV of either power-supply rail.
separate 100nF capacitors.
For example, a MAX4241 running from a single +1.8V
Good PC board lay out techniques optimiz e perforsupply, operating at TA = +25°C, can source 240µA to
mance by decreasing the amount of stray capacitance
within 100mV of V
and is capable of driving a 7kat the op amp’s inputs and output. To decrease stray
load resistor to VEE:
RL =
1.8V - 0.1V
A
X
4
2
4
0
capacitance, minimize trace lengths by placing external components as close as possible to the op amp.
Surface-mount components are an excellent choice.
7kto V
EE
240 
M
The same application can drive a 3.3k load resistor
when terminated in VCC / 2 (+0.9V in this case).

A
X
Driving Capacitive Loads
The MAX4240–MAX4244 are unity-gain stable for loads
up to 200pF (see Load Resistor vs. Capacitive Load
R
graph in Typical Operating Characteristics). Applications that require greater capacitive drive capability
should use an isolation resistor between the output and
results in a loss of gain accuracy because R
voltage divider with the load resistor.
4
2
4
4
R
forms a
CL
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-supp ly operation, bypass the
power supply with a 100nF capacitor to V
(in this
case GND). For dual-supply operation, both the V
R
A =
L
1
ISO
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
100s/div
RISO = NONE, RL = 100k, CL = 700pF
Figure 8b. Pulse Response without Isolating Resistor
–
100s/div
RISO = 1k, RL = 100k, CL = 700pF
Figure 8c. Pulse Response with Isolating Resistor
______________________________________________________________________________________
13
Beyond-the-Rails Op Amps
Using the MAX4240–MAX4244
4
as Comparators
4 Although optimized for use as operational amplifiers,
2 the MAX4240–MAX4244 can also be used as rail-to-rail
4 I/O comparators. Typical propagation delay depends
Using the MAX4240–MAX4244
as Ultra-Low-Power Current Monitors
The MAX4240–MAX4244 are ideal for app lications
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.
Single/Dual/Quad, +1.8V/10µA, SOT23,
X on the input overdrive voltage, as shown in Figure 9.
External
hysteresis
be used
to minimize
the risk
of
A output
oscillation.
Thecan
positive
feedback
circuit,
shown
in Figure 10, causes the input threshold to change
M
– when the output voltage changes state. The two thresholds create a hysteresis band that can be calculated by
0 the following equations:
4
V
=V -V
2
V = V x R2 / (R1 + (R1 x R2 / R
) + R2)
4
V = [(R2 / R1 x V ) + (R2 / R
) x V
]/
X
(1 + R1 / R2 + R2 / R
)
A The MAX4240–MAX4244 contain special circuitry to
boost
drive currents
to thevoltage
amplifier
output
stage. internal
This maximizes
the output
range
over
which the amplifiers are linear. In an open-loop comparator application, the excursion of the output voltage
is so close to the supply rails that the output stage transistors will saturate, causing the quiescent current to
increase from the normal 10µA. Typical quiescent currents increase to 35µA for the output saturating at V
and 28µA for the output at VEE.
The voltage on the load side of the b attery stack is
equal to the voltage at the em itter of Q1, due to the
feedback loop containing the op amp. As the load current increases, the voltage d rop across R1 and R2
increases. Thus, R2 provides a fraction of the load current (set by the ratio of R1 and R2) that flows into the
emitter of the PNP transistor. Neglecting PNP base current, this current flows into R3, producing a ground-referenced 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 = 2, R2 = 100k, R3 = 1M.
The circuit consumes less power (but is more susceptible to noise) with higher values of R1, R2, and R3.
INPUT
VOH
10,000
HYSTERESIS
VHI
VLO
M
VOH
t +; V = +5V
PD
1000
OUTPUT
C
C
VOL
)
t -; V = +5V
P
D

t
D
9g
f4
02
X
C
C
100
VIN
RHYS
T
R1
tP +; C =
D V C +1.8V
VCC
t -; V
PD
VOUT
= +1.8V
CC
10
0
10
20 30
40 50 60 70
80 90 100
R2
VE
MAX4240
MAX4241
E
VO (mV)
D
VEE
Figure 9. Propagation Delay vs. Input Overdrive
14
Figure 10. Hysteresis Comparator Circuit
______________________________________________________________________________________
MAX4242
MAX4243
MAX4244
Beyond-the-Rails Op Amps
M
___________________Chip Information
A
X
MAX4240/MAX4241
TRANSISTOR COUNT: 234
MAX4242/MAX4243
R1
4
2
4
0
TRANSISTOR COUNT: 466
MAX4244
TRANSISTOR COUNT: 932
R2
M
SUBSTRATE CONNECTED TO VEE
Single/Dual/Quad, +1.8V/10µA,
SOT23,
Q1
A
X
VOU
T
R3
4
2
4
4
MAX4240
I
VEE
V
Figure 11. Current Monitor for a 2-Cell Battery Stack
_____________________________________________Pin Configurations (continued)
TOP VIEW
N.C. 1
8
SHDN
OUTA 1
8
VCC
IN- 2
7
VCC
INA- 2
7
OUTB
IN+ 3
6
OUT
INA+ 3
6
INB-
VEE 4
5
N.C.
VEE 4
5
INB+
MAX4241
OUTA 1
10
V
INA- 2
MAX4242
MAX4243
INA+ 3
6 SHDNB
MA
X
SO/MAX
14
V
CC
INA- 2
13
INA+ 3
OUTA 1
14
OUTD
OUTB
INA- 2
13
IND-
12
INB-
INA+ 3
12
IND+
11
INB+
VCC 4
11
VEE
10
N.C.
INB+ 5
10
INC+
SHDNA 6
9
SHDNB
INB- 6
9
INC-
N.C. 7
8
N.C.
OUTB 7
8
OUTC
VEE 4
MAX4243
N.C. 5
SO
8 INB7 INB+
SHDNA 5
OUTA 1
–
9 OUTB
VEE 4
SO/MAX
CC
MAX4244
SO
______________________________________________________________________________________
15
Beyond-the-Rails Op Amps
Tape-and-Reel Information
4
4
2
4
0
2
X
A
M
–
0
4
2
4
X
A
F
Single/Dual/Quad, +1.8V/10µA, SOT23,
K0
A0
E
1.753
0.102
P0 W
B0
3.099
0.102
F
3.505
0.051
P010
D
1.499
+0.102
+0.000
K0
1.397
0.102
P22.007
3.988
0.102
t
0.051
t
0.254
W
8.001
0E
+0.254
M
P
NOTE: DIMENSIONS ARE IN MM.
AND FOLLOW EIA481-1 STANDARD.
D1
0.991
P
D
0.000
0.102
3.988
0
40.005
0.102
0.203
0.127
-0.102
+0.305
Package
5
5
-2
Information
O
(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.)
S
E
L
3
SO
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.