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MAX4244
Technical data
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MAXIM MAX4240, MAX4244 Technical data

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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 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.
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.
Applications
Two-Cell Battery­Powered Systems
Portable/Battery-Powered Electronic Equipment
Digital Scales
Strain Gauges Sensor Amplifiers Cellular Phones Notebook Computers PDAs
Features
♦ Ultra-Low-Voltage Operation:
Guaranteed Down to +1.8V Typical Operation to +1.5V
♦ 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
♦ Unity-Gain Stable for Capacitive Loads up to 200pF
♦ 90kHz Gain-Bandwidth Product
♦ Available in Space-Saving 5-Pin SOT23 and
8-Pin µMAX
®
Packages
Ordering Information
PART TEMP RANGE
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 —
PIN­PACKAGE
TOP
MARK
MAX4240–MAX4244
Selector Guide
PART
MAX4240 1 — 5-pin SOT23
MAX4241 1 Yes 8-pin µMAX/SO
MAX4242 2 — 8-pin µMAX/SO
MAX4243 2 Yes
MAX4244 4 — 14-pin SO
Beyond-the-Rails is a trademark and µMAX is a registered trademark of Maxim Integrated Products, Inc.
NO. OF
AMPS
SHUTDOWN PIN-PACKAGE
10-pin µMAX, 14-pin SO
________________________________________________________________ Maxim Integrated Products 1
TOP VIEW
OUT 1 5 V
V
EE
IN+ 3 4 IN-
Pin Configurations continued at end of data sheet.
Pin Configurations
CC
MAX4240
2
SOT23-5
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.
_______________________________________________________________________________________
MAX4240–MAX4244
Single/Dual/Quad, +1.8V/10µA, SOT23, Beyond-the-Rails Op Amps
ABSOLUTE MAXIMUM RATINGS
Supply Voltage (V
CC
to VEE)....................................................6V
10-pin µMAX (derate 5.6mW/°C above +70°C) ............444mW
All Other Pins ...................................(V
CC
+ 0.3V) to (V
EE
- 0.3V)
14-pin SO (derate 8.33mW/°C above +70°C)...............667mW
Output Short-Circuit Duration (to V
CC
or VEE)............Continuous
Operating Temperature Range ...........................-40°C to +85°C
Continuous Power Dissipation (T
A
= +70°C)
Junction Temperature......................................................+150°C
5-pin SOT23 (derate 7.1mW/°C above +70°C).............571mW
Storage Temperature Range .............................-65°C to +160°C
8-pin µMAX (derate 4.1mW/°C above +70°C) ..............330mW
Lead Temperature (soldering, 10s) .................................+300°C
8-pin SO (derate 5.88mW/°C above +70°C).................471mW
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
(V
CC
= +1.8V to +5.5V, V
EE
= 0, V
CM
= 0, V
OUT
= V
CC
/ 2, R
L
= 100kΩ tied to V
CC
/ 2, SHDN = VCC, TA = +25°C, unless
otherwise noted.) (Note 1)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Supply-Voltage Range V
CC
Inferred from PSRR test 1.8 5.5 V
Supply Current
I
CC
SHDN = V
CC
V
CC
= 1.8V 10 12
µA
per Amplifier
V
CC
= 5.0V 14 18
Shutdown Supply
SHDN = V
EE
V
CC
= 1.8V 1.0 1.5
µA
Current (Note 2)
I
CC(SHDN)
V
CC
= 5.0V 2.0 3.0
MAX4241ESA ±0.20 ±0.75
mVInput Offset Voltage V
OS
(V
EE
- 0.2V) ≤ V
CM
≤
(V
CC
+ 0.2V)
MAX4242ESA/MAX4243ESD/ MAX4244ESD
±0.20 ±0.88
MAX4240EUK/MAX424_EUA/ MAX4243EUB
±0.25 ±1.40
Input Bias Current I
B
(Note 3) ±2 ±6 nA
Input Offset Current I
OS
(Note 3) ±0.5 ±1.5 nA
Differential Input
⎥
V
IN+
- V
IN-
⎥
< 1.0V
45 MΩ
Resistance
R
IN(DIFF)
⎥
V
IN+
- V
IN-
⎥
> 2.5V
4.4 kΩ
Input Common-Mode
V
CM
Inferred from the CMRR test V
EE
- 0.2 V
CC
+ 0.2 V
Voltage Range
MAX4241ESA 72 90
dB
V
CC
= 1.8V
MAX4242ESA/MAX4243ESD/ MAX4244ESD
69 90
Common-Mode Rejection Ratio (Note 4)
CMRR
MAX4240EUK/MAX424_EUA/ MAX4243EUB
63 88
V
CC
= 5.0V
MAX4241ESA 74 94
MAX4242ESA/MAX4243ESD/ MAX4244ESD
74 94
MAX4240EUK/MAX424_EUA/ MAX4243EUB
69 90
2
Single/Dual/Quad, +1.8V/10µA, SOT23,
Beyond-the-Rails Op Amps
ELECTRICAL CHARACTERISTICS (continued)
(V
CC
= +1.8V to +5.5V, V
EE
= 0, V
CM
= 0, V
OUT
= V
CC
/ 2, R
L
= 100kΩ tied to V
CC
/ 2, SHDN = VCC, TA = +25°C, unless
otherwise noted.) (Note 1)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
MAX4241ESA 77 85
dB
Power-Supply Rejection Ratio
PSRR 1.8V ≤ V
CC
≤ 5.5V
MAX4242ESA/MAX4243ESD/ MAX4244ESD
77 85
MAX4240EUK/MAX424_EUA/ MAX4243EUB
75 82
V
CC
= 1.8V
R
L
= 100kΩ 76 85
dB
Large-Signal
A
VOL
(V
EE
+ 0.2V) ≤ V
OUT
≤
R
L
= 10kΩ 66 73
Voltage Gain
(V
CC
- 0.2V) V
CC
= 5.0V
R
L
= 100kΩ 86 94
R
L
= 10kΩ 78 85
V
CC
= 1.8V
R
L
= 100kΩ 8 20
mV
Output Voltage
V
OH
Specified as
R
L
= 10kΩ 40 65
Swing High
⎥ V
CC
- V
OH
⎥
V
CC
= 5.0V
R
L
= 100kΩ 10 25
R
L
= 10kΩ 60 95
V
CC
= 1.8V
R
L
= 100kΩ 6 15
mV
Output Voltage
V
OL
Specified as
R
L
= 10kΩ 23 35
Swing Low
⎥ V
EE
- V
OL
⎥
V
CC
= 5.0V
R
L
= 100kΩ 10 20
R
L
= 10kΩ 40 60
Output Short-Circuit
Sourcing 0.7
mA
Current
I
OUT(SC)
Sinking 2.5
Output Leakage Current in Shutdown
I
OUT(SHDN)
SHDN = V
EE
= 0, V
CC
= 5.5V
20 50 nA
(Notes 2, 5)
SHDN Logic Low (Note 2)
V
IL
0.3 x V
CC
V
SHDN Logic High (Note 2)
V
IH
0.7 x V
CC
V
SHDN Input Bias Current (Note 2)
IIH, I
IL
SHDN = V
CC
= 5.5V or SHDN = V
EE
= 0
40 80 nA
Channel-to-Channel Isolation (Note 6)
CH
ISO
Specified at DC 80 dB
Gain-Bandwidth Product
GBW 90 kHz
Phase Margin
Φ
m
68 degrees
Gain Margin G
m
18 dB
Slew Rate SR 40 V/ms
MAX4240–MAX4244
_______________________________________________________________________________________ 3
_______________________________________________________________________________________
MAX4240–MAX424
Single/Dual/Quad, +1.8V/10µA, SOT23, Beyond-the-Rails Op Amps
ELECTRICAL CHARACTERISTICS (continued)
(V
CC
= +1.8V to +5.5V, V
EE
= 0, V
CM
= 0, V
OUT
= V
CC
/ 2, R
L
= 100kΩ tied to V
CC
/ 2, SHDN = VCC, TA = +25°C, unless
otherwise noted.) (Note 1)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Density
e
n
f = 1kHz 70
nV/√Hz
Density
i
n
f = 1kHz 0.05
pA/√Hz
Capacitive-Load Stability
A
VCL
= +1V/V, no sustained oscillations 200 pF
Shutdown Time t
SHDN
50 µs
Enable Time from Shutdown
t
ENABLE
150 µs
Power-Up Time t
ON
200 µs
Input Capacitance C
IN
3 pF
Total Harmonic Distortion
THD f
IN
= 1kHz, V
CC
= 5.0V, V
OUT
= 2Vp-p, AV = +1V/V 0.05 %
Settling Time to 0.01% t
S
AV = +1V/V, V
CC
= 5.0V, V
OUT
= 2V
STEP
50 µs
ELECTRICAL CHARACTERISTICS
(V
CC
= +1.8V to +5.5V, V
EE
= 0, V
CM
= 0, V
OUT
= V
CC
/ 2, R
L
= 100kΩ tied to V
CC
/ 2, SHDN = VCC, TA = T
MIN
to T
MAX
, unless oth-
erwise noted.) (Note 1)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Supply-Voltage Range V
CC
Inferred from PSRR test 1.8 5.5 V
Supply Current
I
CC
SHDN = V
CC
V
CC
= 1.8V 14
µA
per Amplifier
V
CC
= 5.0V 19
Shutdown Supply
SHDN = V
EE
V
CC
= 1.8V 2.0
µA
Current (Note 2)
I
CC(SHDN)
V
CC
= 5.0V 3.5
MAX4241ESA ±1.2
mVInput Offset Voltage V
OS
(V
EE
- 0.2V) ≤ V
CM
≤
(V
CC
+ 0.2V)
MAX4242ESA/MAX4243ESD/ MAX4244ESD
±1.3
MAX4240EUK/MAX424_EUA/ MAX4243EUB
±2.0
Input Offset Voltage Drift
TC
VOS
2 µV/°C
Input Bias Current I
B
(Note 3) ±15 nA
Input Offset Current I
OS
(Note 3) ±7 nA
Input Common-Mode Voltage Range
V
CM
Inferred from the CMRR test -0.2 V
CC
+ 0.2 V
4
Input Voltage-Noise
Input Current-Noise
Single/Dual/Quad, +1.8V/10µA, SOT23,
Beyond-the-Rails Op Amps
ELECTRICAL CHARACTERISTICS
(V
CC
= +1.8V to +5.5V, V
EE
= 0, V
CM
= 0, V
OUT
= V
CC
/ 2, R
L
= 100kΩ tied to V
CC
/ 2, SHDN = VCC, TA = T
MIN
to T
MAX
, unless oth-
erwise noted.) (Note 1)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
MAX4241ESA 65
dB
V
CC
= 1.8V
MAX4242ESA/MAX4243ESD/ MAX4244ESD
65
Common-Mode Rejection Ratio (Note 4)
CMRR
MAX4240EUK/MAX424_EUA/ MAX4243EUB
61
V
CC
= 5.0V
MAX4241ESA 71
MAX4242ESA/MAX4243ESD/ MAX4244ESD
71
MAX4240EUK/MAX424_EUA/ MAX4243EUB
67
MAX4241ESA 73
dB
Power-Supply Rejection Ratio
PSRR 1.8V ≤ V
CC
≤ 5.5V
MAX4242ESA/MAX4243ESD/ MAX4244ESD
73
MAX4240EUK/MAX424_EUA/ MAX4243EUB
71
V
CC
= 1.8V
R
L
= 100kΩ 72
dB
Large-Signal
A
VOL
(V
EE
+ 0.2V) ≤ V
OUT
≤
R
L
= 10kΩ 62
Voltage Gain
(V
CC
- 0.2V) V
CC
= 5.0V
R
L
= 100kΩ 80
R
L
= 10kΩ 72
V
CC
= 1.8V
R
L
= 100kΩ 25
mV
Output Voltage
V
OH
Specified as
R
L
= 10kΩ 95
Swing High
⎥ V
CC
- V
OH
⎥
V
CC
= 5.0V
R
L
= 100kΩ 30
R
L
= 10kΩ 145
V
CC
= 1.8V
R
L
= 100kΩ 20
mV
Output Voltage
V
OL
Specified as
R
L
= 10kΩ 50
Swing Low
⎥ V
EE
- V
OL
⎥
V
CC
= 5.0V
R
L
= 100kΩ 25
R
L
= 10kΩ 75
Output Leakage Current in Shutdown
I
OUT(SHDN)
SHDN = V
EE
= 0, V
CC
= 5.5V
100 nA
(Notes 2, 5)
SHDN Logic Low (Note 2)
V
IL
0.3 x V
CC
V
MAX4240–MAX4244
_______________________________________________________________________________________ 5
MAX4240–MAX4244
Single/Dual/Quad, +1.8V/10µA, SOT23, Beyond-the-Rails Op Amps
ELECTRICAL CHARACTERISTICS (continued)
(V
CC
= +1.8V to +5.5V, V
EE
= 0, V
CM
= 0, V
OUT
= V
CC
/ 2, R
L
= 100kΩ tied to V
CC
/ 2, SHDN = VCC, TA = T
MIN
to T
MAX
, unless oth-
erwise noted.) (Note 1)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
SHDN Logic High (Note 2)
V
IH
0.7 x V
CC
V
SHDN Input Bias Current (Note 2)
IIH, I
IL
SHDN = V
CC
= 5.5V or SHDN = V
EE
= 0
120 nA
__________________________________________Typical Operating Characteristics
(V
CC
= +5.0V, V
EE
= 0, V
CM
= V
CC
/ 2, V
SHDN
= VCC, R
L
= 100kΩ to V
CC
/ 2, TA = +25°C, unless otherwise noted.)
SUPPLY CURRENT PER AMPLIFIER
SHUTDOWN SUPPLY CURRENT
MINIMUM OPERATING VOLTAGE
vs. TEMPERATURE
PER AMPLIFIER vs. TEMPERATURE
vs. TEMPERATURE
20 5 1.8
2
-60 -40 -20
0
20 40 100
MAX4240/44-02
60
80
VCC = +5.5V
VCC = +1.8V
1.3
0
-60 -40 -20 20
40
100
MAX4240/44-01
0 60 80
VCC = +5.5V
VCC = +1.8V
SHUTDOWN SUPPLY CURRENT (µA)
0
1.0
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
-60 -40 -20 20
40
100
MAX4240/44-03
0 60 80
PSRR ≥ 80dB
INPUT OFFSET VOLTAGE
INPUT BIAS CURRENT
INPUT BIAS CURRENT vs.
vs. TEMPERATURE
vs. TEMPERATURE
COMMON-MODE VOLTAGE (V
CC
= 1.8V)
18
1.7 16
4
1.6
INPUT OFFSET VOLTAGE (µV)
SUPPLY CURRENT (µA)
14
1.5
12
3
I
BIAS
(nA) V
CC
(V)
1.4
10
8 6
1.2
4
1
1.1
2
5.0
0
400
VCM = 0
VCC = +1.8V
VCC = +5.5V
MAX4240/44-05
2.5
-1
300
0
-2
200
-3
-2.5
100
-60 -40 -20 20
40
100
MAX4240/44-04
0 60 80
INPUT BIAS CURRENT (nA)
-5.0
-4
0
-60 -40 -20
0
20
40
60 80
100
TEMPERATURE (°C)
TEMPERATURE (°C)
VCM (V)
-0.2 0.2 0.6 1.0 1.4
MAX4240/44-06a
1.8
V
CC
= +1.8V
6 _______________________________________________________________________________________
Note 1: The MAX4240EUK, MAX4241EUA, MAX4242EUA, and MAX4243EUB specifications are 100% tested at T
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 V Note 4: Tested over the specified input common-mode range. Note 5: Tested for 0 ≤ V Note 6: Channel-to-channel isolation specification applies to the MAX4242/MAX4243/MAX4244 only.
OUT
≤ V
. Does not include current through external feedback network.
CC
= +0.5V and +0.5V ≤ V
CC
CM
≤ +4.5V.
= +25°C. All
A
-80
-100
-95
-85
-90
100
110
90
Single/Dual/Quad, +1.8V/10µA, SOT23,
Beyond-the-Rails Op Amps
____________________________________Typical Operating Characteristics (continued)
(V
CC
= +5.0V, V
EE
= 0, V
CM
= V
CC
/ 2, V
SHDN
= VCC, R
L
= 100kΩ to V
CC
/ 2, TA = +25°C, unless otherwise noted.)
INPUT BIAS CURRENT vs.
OUTPUT SWING HIGH
OUTPUT SWING LOW
COMMON-MODE VOLTAGE (V
CC
= 5.5V)
vs. TEMPERATURE
vs. TEMPERATURE
5.0
-5.0
-2.5
2.5
MAX4240/44-06b
I
BIAS
(nA)
0
V
CC
= +5.5V
120
0
20
100
80
MAX4240/44-07
VOLTAGE FROM V
CC
(mV)
60
40
VCC = +1.8V, RL = 10kΩ
RL TO V
EE
VCC = +5.5V, RL = 20kΩ
VCC = +5.5V, RL = 100kΩ
VCC = +1.8V, RL = 100kΩ
120
0
20
100
80
MAX4240/44-08
VOLTAGE FROM V
EE
(mV)
60
40
VCC = +1.8V, RL = 10kΩ
VCC = +5.5V, RL = 20kΩ
VCC = +5.5V, RL = 100kΩ
VCC = +1.8V, RL = 100kΩ
RL TO V
CC
-0.5 0.5
1.5
2.5
VCM (V)
3.5
4.5
5.5
-60 -40 -20 20
40
TEMPERATURE (°C)
0 60 80
100
-60 -40 -20 20
40
TEMPERATURE (°C)
0 60 80
100
COMMON-MODE REJECTION
vs. TEMPERATURE
OPEN-LOOP GAIN vs. OUTPUT SWING LOW
(V
CC
= +1.8V, RL TIED TO VEE)
OPEN-LOOP GAIN vs. OUTPUT SWING HIGH
(V
CC
= +1.8V, RL TIED TO VEE)
100
100
RL = 100kΩ
RL = 10kΩ
MAX4240/44-10
50
50
40
40 30
30
-60 -40 -20
0
20
40
60 80
100
0 100
200
300
400
500
0 100
200
300
400
500
TEMPERATURE (°C)
ΔV
OUT
(mV)
ΔV
OUT
(mV)
RL = 100kΩ
RL = 10kΩ
OPEN-LOOP GAIN vs. OUTPUT SWING LOW
OPEN-LOOP GAIN vs. OUTPUT SWING HIGH
OPEN-LOOP GAIN
(V
CC
= +5.5V, RL TIED TO VEE)
(V
CC
= +5.5V, RL TIED TO VEE)
vs. TEMPERATURE
MAX4240/44-11
VCC = +1.8V
VCC = +5.5V
MAX4240/44-09
80
90
90
GAIN (dB)
COMMON-MODE REJECTION (dB)
80
GAIN (dB)
GAIN (dB)
GAIN (dB)
70
70
60
60
110
110
0 100 200 300 400
MAX4240/44-13
RL = 20kΩ
RL = 100kΩ
GAIN (dB)
100
90
0 100 200 300 400
MAX4240/44-12
RL = 100kΩ
RL = 20kΩ
85 60
60 80
50
50
75
40
40
70
MAX4240/44-14
VCC = +5.5V, RL = 20kΩ TO V
CC
VCC = +5.5V, RL = 20kΩ TO V
EE
VCC = +1.8V, RL = 10kΩ TO V
EE
VCC = +1.8V, RL = 10kΩ TO V
CC
105
100
95 80
90 70
MAX4240–MAX4244
-60 -40 -20
0
20
40
60 80
100
ΔV
OUT
(mV)
ΔV
OUT
(mV)
TEMPERATURE (°C)
_______________________________________________________________________________________
7
80
70
Single/Dual/Quad, +1.8V/10µA, SOT23, Beyond-the-Rails Op Amps
8 _______________________________________________________________________________________
Typical Operating Characteristics (continued)
(V
CC
= +5.0V, V
EE
= 0, V
CM
= VCC/2, V
SHDN
= VCC, RL= 100kΩ to VCC/2, TA= +25°C unless otherwise noted.)
PHASE (DEGREES)
GAIN AND PHASE vs. FREQUENCY
(C
L
= 100pF)
MAX4240/44-17
60
40
AV = +1000V/V
50
30
GAIN (dB)
20
10
0
-10
-20
-30
-144
-40
-180
10 100 1k 10k 100k
FREQUENCY (Hz)
180
-108
-36
-72
36
0
72
108
144
/
VOLTAGE NOISE vs. FREQUENCY
FREQUENCY (Hz)
VOLTAGE NOISE DENSITY (nV√Hz)
MAX4240 toc20
0.1 1 10
10
100
1000
MAX4240–MAX4244
OPEN-LOOP GAIN
vs. TEMPERATURE
110
105
100
VCC = +5.5V, RLTO V
95
90
GAIN (dB)
85
80
75
70
VCC = +1.8V, RLTO V
VCC = +1.8V, RLTO V
-60 -40 -20 20
VCC = +5.5V, RLTO V
CC
EE
CC
06
TEMPERATURE (°C)
40
EE
0 80
MAX4242/MAX4243/MAX4244
100
60
50
MAX4240/44-15
40
30
20
10
GAIN (dB)
0
-10
-20
-30
-40
TOTAL HARMONIC DISTORTION PLUS NOISE
CROSSTALK vs. FREQUENCY
-60
-70
-80
GAIN (dB)
-90
RL = 10k1
MAX4240/44-18
0.1
THD + NOISE (%)
GAIN AND PHASE vs. FREQUENCY
= 0pF)
(C
L
10 100 1k 10k 100k
FREQUENCY (Hz)
MAX4240/44-16
AV = +1000V/V
vs. FREQUENCY
1
180
144
108
72
36
0
-36
-72
-108
-144
-180
MAX4240/44-19
PHASE (DEGREES)
-100
-110 10
1000
)
1
(k
100
LOAD
R
10
100
LOAD RESISTOR vs.
CAPACITIVE LOAD
OVE
REGION OF
STA
BLE OPERATION
250
0
1k
FREQUENCY (Hz)
10%
RSHOOT
MAR
GINAL
500
C
(pF)
LOAD
REGIO
N OF
STABILITY
750
10k
MAX4240/44-21
MAX4240/44-20
1000
RL = 100k1
0.01 1
1
0
FREQUENCY (Hz)
SMALL-SIGNAL TRANSIENT RESPONSE
(NONINVERTING)
IN
mV/div
OUT
10μs/div
100
RL = 10k
MAX4240/44-22
1
1000
SMALL-SIGNAL TRANSIENT RESPONSE
(INVERTING)
100mV
IN
0V
50mV/div
100mV
OUT
0V
10μs/div
MAX4240/44-23
100mV
0V
100mV
0V
MAX4240–MAX4244
Single/Dual/Quad, +1.8V/10µA, SOT23,
Beyond-the-Rails Op Amps
_______________________________________________________________________________________ 9
Typical Operating Characteristics (continued)
(V
CC
= +5.0V, V
EE
= 0, V
CM
= VCC/2, V
SHDN
= VCC, RL= 100kΩ to VCC/2, TA= +25°C unless otherwise noted.)
Pin Description
Single/Dual/Quad, +1.8V/10µA, SOT23, Beyond-the-Rails Op Amps
MAX4240–MAX424
_______________Detailed Description
Beyond-the-Rails Input Stage
input stage consists of separate NPN and PNP differen­tial stages, which operate together to provide a com­mon-mode range extending to 200mV beyond both supply rails. The crossover region of these two pairs occurs halfway between V
CC
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 volt­ages (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:
I
BIAS
= (V
DIFF
- 1.8V) / 4.4kΩ
R3
V
IN
R3 = R1 R2
R1 R2
MAX4240 MAX4241 MAX4242 MAX4243 MAX4244
Figure 1a. Minimizing Offset Error Due to Input Bias Current (Noninverting)
R3
R3 = R1 R2
R1 R2
MAX4240 MAX4241 MAX4242 MAX4243 MAX4244
V
IN
Figure 1b. Minimizing Offset Error Due to Input Bias Current (Inverting)
2.2k
2.2k
IN-
IN+
Figure 2. Input Protection Circuit
10 ______________________________________________________________________________________
Ω
Ω
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
Single/Dual/Quad, +1.8V/10µA, SOT23,
Beyond-the-Rails Op Amps
RL = 100kΩ TIED TO V
EE
VIN = 2.0V f
IN
= 1kHz
IN
In the region where the differential input voltage
MAX4240-44 fig03
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.
1V/div
1V/div
200µs/div
Figure 3. Rail-to-Rail Input/Output Voltage Range
MAX4240–MAX4244
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 (V
EE
+ 6mV) to (V
CC
- 8mV) with a 100kΩ
load.
__________Applications Information
Power-Supply Considerations
The MAX4240–MAX4244 operate from a single +1.8V to +5.5V supply (or dual ±0.9V to ±2.75V supplies) and
100
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
90
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, volt­age at end-of-life, capacity, and approximate operating time from a MAX4240/MAX4241, assuming nominal conditions for both normal and shutdown modes.
PSRR (dB)
80
70
TA = +85°C
TA = -40°C
TA = +25°C
MAX4240-44 fig04
Although the amplifiers are fully guaranteed over tem-
60
perature for operation down to a +1.8V single supply,
1.0 1.2
1.4 1.6 1.8
2.0
even lower-voltage operation is possible in practice.
SUPPLY VOLTAGE (V)
Figures 4 and 5 show the PSRR and supply current as a function of supply voltage and temperature.
Figure 4. Power-Supply Rejection Ratio vs. Supply Voltage
Power-Up Settling Time
The MAX4240–MAX4244 typically require 200µs to
12
power up after V
CC
is stable. During this start-up time,
the output is indeterminant. The application circuit
10
TA = +85°C
TA = +25°C
TA = -40°C
MAX4240-44 fig05
should allow for this initial delay.
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
SUPPLY CURRENT (µA)
8
6
4
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
2
0
1.0 1.2
1.4 1.6 1.8
2.0
mode when SHDN is left floating. Figure 6 shows the
SUPPLY VOLTAGE (V)
output voltage response to a shutdown pulse. The logic threshold for SHDN is always referred to V
CC
/ 2 (not to
Figure 5. Supply Current vs. Supply Voltage
______________________________________________________________________________________ 11
______________________________________________________________________________________
MAX4240–MAX4244
Single/Dual/Quad, +1.8V/10µA, SOT23, Beyond-the-Rails Op Amps
Table 1. MAX4240/MAX4241 Characteristics with Typical Battery Systems
BATTERY TYPE RECHARGEABLE
V
FRESH
(V)
V
END-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 10
6
Nickel­Cadmium (2 Cells)
Yes 2.4 1.8 750 75,000 0.75 x 10
6
Lithium-Ion (1 Cell) Yes 3.5 2.7 1000 100,000 10
6
Nickel-Metal­Hydride (2 Cells)
Yes 2.4 1.8 1000 100,000 10
6
VIN = 2V R
L
= 100kΩ TIED TO V
EE
MAX4240-44 fig06
1200
VCC = 5.5V, VOH = 200mV
VCC = 1.8V, V
OH
= 200mV
VCC = 5.5V, VOH = 100mV
V
CC
= 1.8V,
V
OH
= 100mV
VCC =
VCC =
1.8V,
5.5V, V VOH =
OH
= 5
50mV
0mV
MAX4240-44 fig07a
SHDN
OUTPUT SOURCE CURRENT (µA)
1000
800
600
400
200
0
5V/div
1V/div
OUT
200µs/div
-60 -40 -20
0 20 40 60 80
100
TEMPERATURE (°C)
Figure 6. Shutdown Enable/Disable Output Voltage
Figure 7a. Output Source Current vs. Temperature
GND). When using dual supplies, pull SHDN to V
EE
to
enter shutdown mode.
3000
Load-Driving Capability
The MAX4240–MAX4244 are fully guaranteed over tem­perature and supply voltage to drive a maximum resis-
tive load of 10kΩ to V
CC
/ 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 magni-
OUTPUT SINK CURRENT (µA)
2500
2000
1500
1000
tude of this current source/sink varies with supply
500
voltage, ambient temperature, and lot-to-lot variations of the units.
0
, VOL
VCC
VCC = 5.5V, VOL = 200mV
VCC = 1.8V = 200mV
VCC = 5.5V, V
OL
= 100mV
VCC = 1.8V, VOL = 100mV
= 5.5V, VOL = 50mV
VCC = 1.8V, VOL = 50mV
MAX4240-44 fig07b
Figures 7a and 7b show the typical current source and sink capability of the MAX4240–MAX4244 family as a
-60 -40 -20 TEMPERATURE (°C)
0 4020 60 80
100
function of supply voltage and ambient temperature. The contours on the graph depict the output current
Figure 7b. Output Sink Current vs. Temperature
12
Single/Dual/Quad, +1.8V/10µA, SOT23,
Beyond-the-Rails Op Amps
value, based on driving the output voltage to within and V
EE
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 layout techniques optimize perfor­supply, operating at TA = +25°C, can source 240µA to mance by decreasing the amount of stray capacitance within 100mV of V
CC
and is capable of driving a 7kΩ at the op amp’s inputs and output. To decrease stray
load resistor to V
EE
: capacitance, minimize trace lengths by placing exter-
nal components as close as possible to the op amp.
1.8V - 0.1V
Surface-mount components are an excellent choice.
RL = = 7kΩ
to V
EE
240 A
µ
The same application can drive a 3.3kΩ load resistor
when terminated in V
CC
/ 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
). Applica­tions 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 R
ISO
forms a
voltage divider with the load resistor.
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 V
EE
(in this
case GND). For dual-supply operation, both the V
CC
Figure 8a Using a Resistor to Isolate a Capacitive Load from the Op Amp
R
ISO
C
L
R
L
MAX4240 MAX4241 MAX4242 MAX4243 MAX4244
AV =
R
L
≈ 1
R
L
+ R
ISO
50mV/div
IN
OUT
50mV/div
MAX4240-44 fig08b
100µs/div
R
ISO
= NONE, RL = 100kΩ, CL = 700pF
50mV/div
IN
OUT
50mV/div
MAX4240-44 fig08c
100µs/div
R
ISO
= 1kΩ, RL = 100kΩ, CL = 700pF
MAX4240–MAX4244
Figure 8b. Pulse Response without Isolating Resistor
Figure 8c. Pulse Response with Isolating Resistor
______________________________________________________________________________________ 13
Single/Dual/Quad, +1.8V/10µA, SOT23, Beyond-the-Rails Op Amps
MAX4240–MAX4244
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 thresh­olds create a hysteresis band that can be calculated by the following equations:
V
HYST
= V
HI
- V
LO
V
LO
= V
IN
x R2 / (R1 + (R1 x R2 / R
HYST
) + R2)
V
HI
= [(R2 / R1 x VIN) + (R2 / R
HYST
) x VCC] /
(1 + R1 / R2 + R2 / R
HYST
)
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 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
CC
and 28µA for the output at VEE.
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 cur­rent increases, the voltage drop 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 V
OS
of the op amp, in order to minimize errors.
The output voltage of the application can be calculated using the following equation:
V
OUT
= [I
LOAD
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 suscepti­ble to noise) with higher values of R1, R2, and R3.
R2
R1
V
IN
OUTPUT
INPUT
V
OH
V
OL
V
EE
V
CC
V
OUT
R
HYST
V
EE
MAX4240 MAX4241 MAX4242 MAX4243 MAX4244
HYSTERESIS
V
LO
V
OH
V
HI
MAX4240-44 fig09
t
PD
(µs)
tPD-; V
CC
= +5V
tPD+; V
CC
= +1.8V
tPD-; V
CC
= +1.8V
tPD+; V
CC
= +5V
10,000
1000
100
10
0 10 20 30
40 50 60 70 80
90
100
V
OD
(mV)
Figure 9. Propagation Delay vs. Input Overdrive Figure 10. Hysteresis Comparator Circuit
14 ______________________________________________________________________________________
Single/Dual/Quad, +1.8V/10µA, SOT23,
Beyond-the-Rails Op Amps
___________________Chip Information
MAX4240/MAX4241
TRANSISTOR COUNT: 234
MAX4242/MAX4243
TRANSISTOR COUNT: 466
MAX4244
TRANSISTOR COUNT: 932
SUBSTRATE CONNECTED TO V
EE
Figure 11. Current Monitor for a 2-Cell Battery Stack
_____________________________________________Pin Configurations (continued)
OUT
N.C.V
EE
1 2
8 7 SHDN
V
CC
IN-
IN+
N.C.
SO/µMAX
TOP VIEW
3
4
6
5
MAX4241
INB-
INB+V
EE
1 2
8 7 V
CC
OUTBINA-
INA+
OUTA
SO/µMAX
3
4
6
5
MAX4242
1 2 3 4 5
10
9 8 7 6
V
CC
OUTB INB­INB+V
EE
INA+
INA-
OUTA
MAX4243
µMAX
SHDNBSHDNA
14 13 12 11 10
9 8
1 2 3 4 5 6 7
OUTD IND­IND+ V
EE
V
CC
INA+
INA-
OUTA
MAX4244
INC+ INC­OUTCOUTB
INB-
INB+
SO
14 13 12 11 10
9 8
1 2 3 4 5 6 7
V
CC
OUTB INB­INB+V
EE
INA+
INA-
OUTA
MAX4243
N.C. SHDNB N.C.N.C.
SHDNA
N.C.
SO
MAX4240–MAX4244
______________________________________________________________________________________ 15
R2
I
LOAD
R1
V
CC
Q1
V
OUT
R3
MAX4240
V
EE
MAX4240–MAX4244
Single/Dual/Quad, +1.8V/10µA, SOT23, Beyond-the-Rails Op Amps
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.
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.)
Tape-and-Reel Information
Revision History
Pages changed at Rev 3: 1, 8, 9, 16
E
F
NOTE: DIMENSIONS ARE IN MM. AND FOLLOW EIA481-1 STANDARD.
A
0
B
0
D
D
1
D
3.200
3.099
1.499
+0.254
0.991 +0.000
±0.102
±0.102
+0.102 +0.000
1.753
3.505
1.397
3.988
P
A
2
0
±0.102
±0.051
±0.102
±0.102
P
0
D
1
P
E
F
K
0
P
W
B
0
t
K
0
P
0
P
0
P
2
t 0.254 ±0.127
W 8.001
3.988 ±0.102
10 40.005 ±0.203
2.007 ±0.051
+0.305
-0.102
5 SOT23-5
SOT-23 5L .EPS
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