Rainbow Electronics MAX4244 User Manual

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________________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-the­rails 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/low-voltage
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 Battery- Strain Gauges
Powered Systems

Sensor Amplifiers

Portable/Battery-Powered Cellular Phones
Electronic Equipment

Notebook Computers

Digital Scales 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

MAX4240–MAX4244

Single/Dual/Quad, +1.8V/10µA, SOT23,

Beyond-the-Rails Op Amps

________________________________________________________________

Maxim Integrated Products

1

V

EE

IN-IN+

15V

CC

OUT

MAX4240

SOT23-5

TOP VIEW

2

34

_________________Pin Configurations

19-1343; Rev 0; 3/98

PART

MAX4240EUK-T
MAX4241EUA

MAX4241ESA -40°C to +85°C

-40°C to +85°C

-40°C to +85°C

TEMP. RANGE

PIN-

PACKAGE

5 SOT23-5
8 µMAX
8 SO

_______________Ordering Information

Pin Configurations continued at end of data sheet.

_____________________Selector Guide

NO. OF

AMPS

PIN-PACKAGE

MAX4240 1 5-pin SOT23
MAX4241 1 8-pin µMAX/SO

PART

MAX4242 2 8-pin µMAX/SO

SHUTDOWN

—

Yes

—

MAX4243 2

10-pin µMAX,
14-pin SO

MAX4244 4 14-pin SO

Yes

—

Beyond-the-Rails is a trademark of Maxim Integrated Products.
Rail-to-Rail is a registered trademark of Nippon Motorola Ltd.

MAX4242EUA
MAX4242ESA
MAX4243EUB

-40°C to +85°C

-40°C to +85°C

-40°C to +85°C 8 µMAX
8 SO
10 µMAX

MAX4243ESD
MAX4244ESD

-40°C to +85°C

-40°C to +85°C 14 SO
14 SO

SOT

TOP MARK

ACCS

—
—
—
—
—
—
—

MAX4240–MAX4244

Single/Dual/Quad, +1.8V/10µA, SOT23,
Beyond-the-Rails Op Amps

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS — T

A

= +25°C

(VCC= +1.8V to +5.5V, VEE= 0, VCM= 0, V

OUT

= VCC/ 2, RL= 100kΩ tied to VCC/ 2, SHDN = VCC, TA= +25°C, unless

otherwise noted.) (Note 1)

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.

Supply Voltage (VCCto VEE)....................................................6V

All Other Pins ...................................(V

CC

+ 0.3V) to (VEE- 0.3V)

Output Short-Circuit Duration (to V

CC

or VEE)............Continuous

Continuous Power Dissipation (T

A

= +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, 10sec).............................+300°C

PARAMETER SYMBOL MIN TYP MAX UNITS

Input Bias Current I

B

±2 ±6 nA

CONDITIONS

Input Offset Voltage V

OS

±0.20 ±0.75

mV

MAX4241ESA

(VEE- 0.2V) ≤ VCM≤
(VCC+ 0.2V)

±0.25 ±1.40

MAX4240EUK/MAX424_EUA/
MAX4243EUB

±0.20 ±0.88

MAX4242ESA/MAX4243ESD/
MAX4244ESD

Supply Current
per Amplifier

I

CC

10 12

µA

VCC= 1.8V

SHDN = V

CC

14 18VCC= 5.0V

2.0 3.0VCC= 5.0V

Shutdown Supply
Current (Note 2)

I

CC(SHDN)

1.0 1.5
µA

VCC= 1.8V

SHDN = V

EE

Supply-Voltage Range V

CC

1.8 5.5 VInferred from PSRR test

(Note 3)
(Note 3)Input Offset Current I

OS

±0.5 ±1.5 nA



V

IN+

- V

IN-



< 1.0V

Differential Input
Resistance

R

IN(DIFF)

45 MΩ



V

IN+

- V

IN-



> 2.5V

4.4 kΩ

Inferred from the CMRR test

Input Common-Mode
Voltage Range

V

CM

VEE- 0.2 VCC+ 0.2 V

VCC= 1.8V

Common-Mode
Rejection Ratio
(Note 4)

CMRR

72 90

dB

MAX4241ESA

72 90

MAX4242ESA/MAX4243ESD/
MAX4244ESD

66 88

MAX4240EUK/MAX424_EUA/
MAX4243EUB

VCC= 5.0V

77 94MAX4241ESA
77 94

MAX4242ESA/MAX4243ESD/
MAX4244ESD

72 90

MAX4240EUK/MAX424_EUA/
MAX4243EUB

Single/Dual/Quad, +1.8V/10µA, SOT23,

Beyond-the-Rails Op Amps

_______________________________________________________________________________________ 3

ELECTRICAL CHARACTERISTICS — TA= +25°C (continued)

(VCC= +1.8V to +5.5V, VEE= 0, VCM= 0, V

OUT

= VCC/ 2, RL= 100kΩ tied to VCC/ 2, SHDN = VCC, TA= +25°C, unless

otherwise noted.) (Note 1)

Channel-to-Channel
Isolation (Note 6)

CH

ISO

80 dBSpecified at DC

Phase Margin

Φ

m

68 degrees

Gain Margin G

m

18 dB

Slew Rate SR 40 V/ms

SHDN Input Bias
Current (Note 2)

IIH, I

IL

40 80 nA

SHDN = VCC= 5.5V or SHDN = VEE= 0

SHDN Logic Low

(Note 2)

V

IL

0.3 x V

CC

V

6 15

PARAMETER SYMBOL MIN TYP MAX UNITS

23 35

Specified as
VEE- VOL

Output Voltage
Swing Low

10 20

V

OL

40 60

mV

VCC= 5.0V

RL= 10kΩ

RL= 100kΩ

RL= 100kΩ

VCC= 1.8V

RL= 10kΩ

8 20

40 65

Specified as
VCC- VOH

Output Voltage
Swing High

10 25

80 85

V

OH

70 73

60 95

mV

VCC= 5.0V

RL= 10kΩ

2.5

mA

SHDN Logic High
(Note 2)

V

IH

0.7 x V

CC

V

(VEE+ 0.2V) ≤ V

OUT

≤

(VCC- 0.2V)

Large-Signal
Voltage Gain

90 94

A

VOL

82 85

dB

RL= 100kΩ

RL= 100kΩ

CONDITIONS

Sinking

VCC= 1.8V

RL= 10kΩ

VCC= 5.0V

RL= 10kΩ

RL= 100kΩ

RL= 100kΩ

RL= 10kΩ

VCC= 1.8V

Gain-Bandwidth
Product

GBW 90 kHz

Power-Supply
Rejection Ratio

PSRR

80 85

dB

MAX4241ESA

1.8V ≤ VCC≤ 5.5V

MAX4240–MAX4244

78 82

MAX4240EUK/MAX424_EUA/
MAX4243EUB

80 85

MAX4242ESA/MAX4243ESD/
MAX4244ESD

Output Leakage
Current in Shutdown
(Notes 2, 5)

I

OUT(SHDN)

20 50 nA

SHDN = VEE= 0, VCC= 5.5V

Output Short-Circuit
Current

I

OUT(SC)

Sourcing 0.7

MAX4240–MAX4244

Single/Dual/Quad, +1.8V/10µA, SOT23,
Beyond-the-Rails Op Amps

4 _______________________________________________________________________________________

Enable Time from
Shutdown

t

ENABLE

150

Input Voltage Noise
Density

e

n

70

nV/√Hz

Input Current Noise
Density

i

n

0.05

pA/√Hz

Capacitive-Load
Stability

200 pF

Shutdown Time t

SHDN

50 µs

µs

Power-Up Time t

ON

200 µs

Input Capacitance C

IN

3 pF

f = 1kHz

f = 1kHz

A

VCL

= +1V/V, no sustained oscillations

PARAMETER SYMBOL MIN TYP MAX UNITS

Total Harmonic
Distortion

THD 0.05 %

Settling Time to 0.01% t

S

CONDITIONS

50 µs

fIN= 1kHz, VCC= 5.0V, V

OUT

= 2Vp-p, AV= +1V/V

AV= +1V/V, VCC= 5.0V, V

OUT

= 2V

STEP

ELECTRICAL CHARACTERISTICS — TA= +25°C (continued)

(VCC= +1.8V to +5.5V, VEE= 0, VCM= 0, V

OUT

= VCC/ 2, RL= 100kΩ tied to VCC/ 2, SHDN = VCC, TA= +25°C, unless

otherwise noted.) (Note 1)

ELECTRICAL CHARACTERISTICS — TA= T

MIN

to

T

MAX

(VCC= +1.8V to +5.5V, VEE= 0, VCM= 0, V

OUT

= VCC/ 2, RL= 100kΩ tied to VCC/ 2, SHDN = VCC, TA= T

MIN

to T

MAX

, unless oth-

erwise noted.) (Note 1)

SHDN = V

CC

±1.2

Inferred from PSRR test

Inferred from the CMRR test

(Note 3)

CONDITIONS

MAX4241ESA

(VEE- 0.2V) ≤ VCM≤
(VCC+ 0.2V)

mVV

OS

Input Offset Voltage

µA

19

I

CC

SHDN = V

EE

14

V1.8 5.5V

CC

Supply-Voltage Range
Supply Current

per Amplifier

V-0.2 VCC+ 0.2V

CM

Input Common-Mode
Voltage Range

µV/°C2TC

VOS

Input Offset Voltage
Drift

nA±7I

OS

Input Offset Current

UNITSMIN TYP MAXSYMBOLPARAMETER

µA

3.5

I

CC(SHDN)

2.0

Shutdown Supply
Current (Note 2)

VCC= 1.8V
VCC= 5.0V
VCC= 1.8V
VCC= 5.0V

(Note 3) nA±15I

B

Input Bias Current

±1.3

MAX4242ESA/MAX4243ESD/
MAX4244ESD

±2.0

MAX4240EUK/MAX424_EUA/
MAX4243EUB

MAX4240–MAX4244

Single/Dual/Quad, +1.8V/10µA, SOT23,

Beyond-the-Rails Op Amps

_______________________________________________________________________________________ 5

ELECTRICAL CHARACTERISTICS — TA= T

MIN

to

T

MAX

(continued)

(VCC= +1.8V to +5.5V, VEE= 0, VCM= 0, V

OUT

= VCC/ 2, RL= 100kΩ tied to VCC/ 2, SHDN = VCC, TA= T

MIN

to T

MAX

, unless oth-

erwise noted.) (Note 1)

68

MAX4242ESA/MAX4243ESD/
MAX4244ESD

68

SHDN = V

EE

= 0, VCC= 5.5V

RL= 10kΩ

64

CONDITIONS

MAX4240EUK/MAX424_EUA/
MAX4243EUB

MAX4241ESA

VCC= 1.8V

dBCMRR

Common-Mode
Rejection Ratio
(Note 4)

nA100I

OUT(SHDN)

Output Leakage
Current in Shutdown
(Notes 2, 5)

76

UNITSMIN TYP MAXSYMBOLPARAMETER

RL= 100kΩ

dB

76

A

VOL

Large-Signal
Voltage Gain

74

MAX4242ESA/MAX4243ESD/
MAX4244ESD

74

70

MAX4240EUK/MAX424_EUA/
MAX4243EUB

MAX4241ESA

VCC= 5.0V

76

MAX4242ESA/MAX4243ESD/
MAX4244ESD

76

74

MAX4240EUK/MAX424_EUA/
MAX4243EUB

MAX4241ESA

1.8V ≤ VCC≤ 5.5V dBPSRR

Power-Supply
Rejection Ratio

RL= 100kΩ 84

RL= 10kΩ 66

(VEE+ 0.2V) ≤ V

OUT

≤

(VCC- 0.2V)

VCC= 1.8V

VCC= 5.0V

RL= 100kΩ

dB

25

V

OH

Output Voltage
Swing High

RL= 100kΩ 30
RL= 10kΩ

VCC= 1.8V

RL= 10kΩ 95

VCC= 5.0V

Specified as
VCC- VOH

145

RL= 100kΩ

dB

20

V

OL

Output Voltage
Swing Low

RL= 100kΩ 25
RL= 10kΩ

VCC= 1.8V

RL= 10kΩ 50

VCC= 5.0V

Specified as
V

EE

- VOL
75

V0.3 x V

CC

V

IL

SHDN Logic Low
(Note 2)

MAX4240–MAX4244

Single/Dual/Quad, +1.8V/10µA, SOT23,
Beyond-the-Rails Op Amps

6 _______________________________________________________________________________________

ELECTRICAL CHARACTERISTICS — TA= T

MIN

to T

MAX

(continued)

(VCC= +1.8V to +5.5V, VEE= 0, VCM= 0, V

OUT

= VCC/ 2, RL= 100kΩ tied to VCC/ 2, SHDN = VCC, TA= T

MIN

to T

MAX

, unless oth-

erwise noted.) (Note 1)

Note 1: The MAX4240EUK, MAX4241EUA, MAX4242EUA, and MAX4243EUB specifications are 100% tested at T

A

= +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 V

CC

= +5.0V and 0 ≤ VCM≤ 5.0V.

Note 4: Tested over the specified input common-mode range.
Note 5: Tested for 0 ≤ V

OUT

≤ VCC. Does not include current through external feedback network.

Note 6: Channel-to-channel isolation specification applies to the MAX4242/MAX4243/MAX4244 only.

SHDN Logic High
(Note 2)

V

IH

0.7 x V

CC

V

SHDN Input Bias
Current (Note 2)

IIH, I

IL

120 nA

SHDN = VCC= 5.5V or SHDN = VEE= 0

PARAMETER SYMBOL MIN TYP MAX UNITSCONDITIONS

20

0

-60 -40 -20 20

40

100

SUPPLY CURRENT PER AMPLIFIER

vs. TEMPERATURE

6
4
2

16
14

18

MAX4240/44-01

TEMPERATURE (°C)

SUPPLY CURRENT (µA)

0 60

10

8

12

80

VCC = +5.5V

VCC = +1.8V

5

0

-60 -40 -20

0

20 40 100

SHUTDOWN SUPPLY CURRENT

PER AMPLIFIER vs. TEMPERATURE

1

4

MAX4240/44-02

TEMPERATURE (°C)

SHUTDOWN SUPPLY CURRENT (µA)

60

2

3

80

VCC = +5.5V

VCC = +1.8V

1.8

1.0

-60 -40 -20 20

40

100

MINIMUM OPERATING VOLTAGE

vs. TEMPERATURE

1.2

1.1

1.6

1.7

MAX4240/44-03

TEMPERATURE (°C)

V

CC

(V)

0 60

1.4

1.3

1.5

80

PSRR ≥ 80dB

__________________________________________Typical Operating Characteristics

(VCC= +5.0V, VEE= 0, VCM= V

CC

/ 2, V

SHDN

= VCC, RL= 100kΩ to V

CC

/ 2, TA= +25°C, unless otherwise noted.)

400

0

-60 -40 -20 20

40

100

INPUT OFFSET VOLTAGE

vs. TEMPERATURE

100

300

MAX4240/44-04

TEMPERATURE (°C)

INPUT OFFSET VOLTAGE (µV)

0 60

200

80

0

-4

-60 -40 -20 20

40

100

INPUT BIAS CURRENT

vs. TEMPERATURE

-3

-1

MAX4240/44-05

TEMPERATURE (°C)

INPUT BIAS CURRENT (nA)

0 60-280

VCM = 0

VCC = +1.8V

VCC = +5.5V

5.0

-5.0

-0.2 0.2 0.6 1.0 1.4

INPUT BIAS CURRENT vs.

COMMON-MODE VOLTAGE (V

CC

= 1.8V)

-2.5

2.5

MAX4240/44-06a

VCM (V)

I

BIAS

(nA)

0

1.8

V

CC

= +1.8V

MAX4240–MAX4244

Single/Dual/Quad, +1.8V/10µA, SOT23,

Beyond-the-Rails Op Amps

_______________________________________________________________________________________

7

5.0

-5.0

-0.5 0.5

1.5

2.5 3.5

4.5

INPUT BIAS CURRENT vs.

COMMON-MODE VOLTAGE (V

CC

= 5.5V)

-2.5

2.5

MAX4240/44-06b

VCM (V)

I

BIAS

(nA)

0

5.5

V

CC

= +5.5V

120

0

-60 -40 -20 20

40

100

OUTPUT SWING HIGH

vs. TEMPERATURE

20

100

80

MAX4240/44-07

TEMPERATURE (°C)

VOLTAGE FROM V

CC

(mV)

0 60

60

40

80

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

-60 -40 -20 20

40

100

OUTPUT SWING LOW

vs. TEMPERATURE

20

100

80

MAX4240/44-08

TEMPERATURE (°C)

VOLTAGE FROM V

EE

(mV)

0 60

60

40

80

VCC = +1.8V, RL = 10kΩ

VCC = +5.5V, RL = 20kΩ

VCC = +5.5V, RL = 100kΩ

VCC = +1.8V, RL = 100kΩ

RL TO V

CC

-80

-100

-60 -40 -20 20

40

100

COMMON-MODE REJECTION

vs. TEMPERATURE

-95

-85

MAX4240/44-09

TEMPERATURE (°C)

COMMON-MODE REJECTION (dB)

0 60

-90

80

VCC = +1.8V

VCC = +5.5V

100

110

0 100 200 300 400

OPEN-LOOP GAIN vs. OUTPUT SWING LOW

(V

CC

= +5.5V, RL TIED TO VEE)

50

40

90

80

MAX4240/44-12

∆V

OUT

(mV)

GAIN (dB)

70
60

RL = 100kΩ

RL = 20kΩ

100

30

0 100 300 500

OPEN-LOOP GAIN vs. OUTPUT SWING LOW

(V

CC

= +1.8V, RL TIED TO VEE)

50

40

90

80

MAX4240/44-10

∆V

OUT

(mV)

GAIN (dB)

200 400

70
60

RL = 100kΩ

RL = 10kΩ

100

30

0 100 300 500

OPEN-LOOP GAIN vs. OUTPUT SWING HIGH

(V

CC

= +1.8V, RL TIED TO VEE)

50

40

90

80

MAX4240/44-11

∆V

OUT

(mV)

GAIN (dB)

200 400

70
60

RL = 100kΩ

RL = 10kΩ

100

110

0 100 200 300 400

OPEN-LOOP GAIN vs. OUTPUT SWING HIGH

(V

CC

= +5.5V, RL TIED TO VEE)

50

40

90

80

MAX4240/44-13

∆V

OUT

(mV)

GAIN (dB)

70
60

RL = 20kΩ

RL = 100kΩ

110

70

-60 -40 -20 20

40

100

OPEN-LOOP GAIN

vs. TEMPERATURE

75

80

105
100

95

MAX4240/44-14

TEMPERATURE (°C)

GAIN (dB)

0 60

90
85

80

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

____________________________________Typical Operating Characteristics (continued)

(VCC= +5.0V, VEE= 0, VCM= V

CC

/ 2, V

SHDN

= VCC, RL= 100kΩ to V

CC

/ 2, TA= +25°C, unless otherwise noted.)

MAX4240–MAX4244

Single/Dual/Quad, +1.8V/10µA, SOT23,
Beyond-the-Rails Op Amps

8 _______________________________________________________________________________________

____________________________________Typical Operating Characteristics (continued)

(VCC= +5.0V, VEE= 0, VCM= V

CC

/ 2, V

SHDN

= VCC, RL= 100kΩ to V

CC

/ 2, TA= +25°C, unless otherwise noted.)

110

70

-60 -40 -20 20

40

100

OPEN-LOOP GAIN

vs. TEMPERATURE

75

80

105
100

95

MAX4240/44-15

TEMPERATURE (°C)

GAIN (dB)

0 60

90

85

80

VCC = +5.5V, RL TO V

CC

VCC = +5.5V, RL TO V

EE

VCC = +1.8V, RL TO V

CC

VCC = +1.8V, RL TO V

EE

60

-40
10 100 1k 10k 100k

GAIN AND PHASE vs. FREQUENCY

(C

L

= 0pF)

-20

-30

MAX4240/44-16

FREQUENCY (Hz)

GAIN (dB)

0

-10

20
10

30

40

50

180

-180

-108

-144

PHASE (DEGREES)

-36

-72

36
0

72

108

144

AV = +1000V/V

60

-40
10 100 1k 10k 100k

GAIN AND PHASE vs. FREQUENCY

(C

L

= 100pF)

-20

-30

MAX4240/44-17

FREQUENCY (Hz)

GAIN (dB)

0

-10

20
10

30

40

50

180

-180

-108

-144

PHASE (DEGREES)

-36

-72

36
0

72

108

144

AV = +1000V/V

-60

-110
10 1k 10k

100

MAX4242/MAX4243/MAX4244

CROSSTALK vs. FREQUENCY

-100

MAX4240/44-18

FREQUENCY (Hz)

GAIN (dB)

-90

-80

-70

RL = 10kΩ

1

0.01
1 100010010

TOTAL HARMONIC DISTORTION PLUS NOISE

vs. FREQUENCY

0.1

MAX4240/44-19

FREQUENCY (Hz)

THD + NOISE (%)

RL = 10kΩ

RL = 100kΩ

1000

10

0 250 500 1000

LOAD RESISTOR vs.

CAPACITIVE LOAD

MAX4240/44-20

C

LOAD

(pF)

R

LOAD

(kΩ)

750

100

10%

OVERSHOOT

REGION OF

MARGINAL STABILITY

REGION OF

STABLE OPERATION

10µs/div

SMALL-SIGNAL TRANSIENT RESPONSE

(NONINVERTING)

MAX4240/44-21

50mV/div

100mV

100mV

IN

OUT

0V

0V

10µs/div

SMALL-SIGNAL TRANSIENT RESPONSE

(INVERTING)

MAX4240/44-22

50mV/div

100mV

100mV

IN

OUT

0V

0V

MAX4240–MAX4244

Single/Dual/Quad, +1.8V/10µA, SOT23,

Beyond-the-Rails Op Amps

_______________________________________________________________________________________ 9

______________________________________________________________Pin Description

Amplifier Output. High impedance when in
shutdown mode.

OUT1 6 —— — —

4 44 4 11

Negative Supply. Tie to ground for single­supply operation.

V

EE

2

3 —— — —
2 —— — — Inverting InputIN-4

Noninverting InputIN+3

7 108 14 4

1, 5 ——

5, 7,

8, 10

— No Connection. Not internally connected.N.C.—

8 —

Positive SupplyV

CC

5

— — —

— 1, 91, 7 1, 13 1, 7

Outputs for Amplifiers A and B. High imped­ance when in shutdown mode.

OUTA,

OUTB

—

Shutdown Input. Drive high, or tie to VCCfor
normal operation. Drive to VEEto place device
in shutdown mode.

SHDN

—

— 2, 82, 6 2, 12 2, 6

— 3, 73, 5 3, 11 3, 5 Noninverting Inputs to Amplifiers A and B

INA+,

INB+

—

— 5, 6

Inverting Inputs to Amplifiers A and B

INA-,

INB-

—

— 6, 9 —

— —— — 8, 14 Outputs for Amplifiers C and D

OUTC,

OUTD

—

Shutdown Inputs for Amplifiers A and B. Drive
high, or tie to VCCfor normal operation. Drive
to VEEto place device in shutdown mode.

SHDNA,

SHDNB

—

— —— — 9, 13

— —— — 10, 12 Noninverting Inputs to Amplifiers C and D

INC+,

IND+

—

Inverting Inputs to Amplifiers C and D

INC-,

IND-

—

PIN

MAX4243

MAX4244MAX4241

µMAX

MAX4242

SO

MAX4240

FUNCTIONNAME

____________________________________Typical Operating Characteristics (continued)

(VCC= +5.0V, VEE= 0, VCM= V

CC

/ 2, V

SHDN

= VCC, RL= 100kΩ to V

CC

/ 2, TA= +25°C, unless otherwise noted.)

100µs/div

LARGE-SIGNAL TRANSIENT RESPONSE

(INVERTING)

MAX4240/44-24

2V/div

+2V

-2V

-2V

+2V

IN

OUT

LARGE-SIGNAL TRANSIENT RESPONSE

(NONINVERTING)

IN

2V/div

OUT

100µs/div

MAX4240/44-23

4.5V

0.5V

4.5V

0.5V

MAX4240–MAX4244

Single/Dual/Quad, +1.8V/10µA, SOT23,
Beyond-the-Rails Op Amps

10 ______________________________________________________________________________________

_______________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 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 VCCand 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

In the region where the differential input voltage
approaches 1.8V, the input resistance decreases expo­nentially from 45MΩ to 4.4kΩ as the diode block begins
conducting. Conversely, the bias current increases with
the same curve.

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.

__________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
consume only 10µA of supply current per amplifier. A
high power-supply rejection ratio of 90dB 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, volt­age 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.

Power-Up Settling Time

The MAX4240–MAX4244 typically require 200µs to
power up after VCCis stable. During this start-up time,
the output is indeterminant. The application circuit
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
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–MAX4244

Single/Dual/Quad, +1.8V/10µA, SOT23,

Beyond-the-Rails Op Amps

______________________________________________________________________________________ 11

1V/div

OUT

IN

1V/div

MAX4240-44 fig03

200µs/div

RL = 100kΩ TIED TO V

EE

VIN = 2.0V
f

IN

= 1kHz

Figure 3. Rail-to-Rail Input/Output Voltage Range

100

60

1.0 1.2 2.0

70

90

MAX4240-44 fig04

SUPPLY VOLTAGE (V)

PSRR (dB)

1.4 1.6801.8

TA = +85°C

TA = +25°C

TA = -40°C

Figure 4. Power-Supply Rejection Ratio vs. Supply Voltage

12

0

1.0 1.2 2.0

2

4

10

MAX4240-44 fig05

SUPPLY VOLTAGE (V)

SUPPLY CURRENT (µA)

1.4 1.6

6

8

1.8

TA = +85°C

TA = +25°C

TA = -40°C

Figure 5. Supply Current vs. Supply Voltage

MAX4240–MAX4244

GND). When using dual supplies, pull SHDN to VEEto
enter shutdown mode.

Load-Driving Capability

The MAX4240–MAX4244 are fully guaranteed over tem­perature and supply voltage to drive a maximum resis­tive 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 cur­rent 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

Single/Dual/Quad, +1.8V/10µA, SOT23,
Beyond-the-Rails Op Amps

12 ______________________________________________________________________________________

MAX4240-44 fig06

200µs/div

5V/div

1V/div

SHDN

OUT

VIN = 2V
R

L

= 100kΩ TIED TO V

EE

Figure 6. Shutdown Enable/Disable Output Voltage

1200

0

-60 -40 -20 100

200

400

1000

MAX4240-44 fig07a

TEMPERATURE (°C)

OUTPUT SOURCE CURRENT (µA)

0 4020

600

800

8060

VCC = 5.5V, VOH = 200mV

VCC = 5.5V, VOH = 100mV

VCC = 1.8V, VOH = 50mV

VCC = 5.5V, VOH = 50mV

VCC = 1.8V,
V

OH

= 200mV

V

CC

= 1.8V,

V

OH

= 100mV

Figure 7a. Output Source Current vs. Temperature

3000

0

-60 -40 -20 100

500

1000

2500

MAX4240-44 fig07b

TEMPERATURE (°C)

OUTPUT SINK CURRENT (µA)

0 4020

1500

2000

8060

VCC = 5.5V, VOL = 200mV

VCC = 1.8V, VOL = 200mV

VCC = 5.5V,
V

OL

= 100mV

VCC = 1.8V, VOL = 50mV

VCC = 5.5V, VOL = 50mV

VCC = 1.8V, VOL = 100mV

Figure 7b. Output Sink Current vs. Temperature

Table 1. MAX4240/MAX4241 Characteristics with Typical Battery Systems

RECHARGEABLE

V

END-OF-LIFE

(V)

Alkaline (2 Cells) No 3.0
Nickel-

Cadmium (2 Cells)

Yes

1.8

BATTERY TYPE

Lithium-Ion (1 Cell) Yes

2.4

Nickel-Metal­Hydride (2 Cells)

Yes

1.8

V

FRESH

(V)

3.5 2.7

2.4 1.8

CAPACITY,

AA SIZE

(mA-h)

2000

750
1000
1000

MAX4240/MAX4241

OPERATING TIME

IN NORMAL MODE

(Hours)

200,000

75,000
100,000
100,000

MAX4241

OPERATING TIME

IN SHUTDOWN

MODE (Hours)

2 x 10

6

0.75 x 10

6

10

6

10

6

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 VCCand is capable of driving a 7kΩ
load resistor to VEE:

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

). 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 VEE(in this
case GND). For dual-supply operation, both the V

CC

and VEEsupplies should be bypassed to ground with
separate 100nF capacitors.

Good PC board layout techniques optimize perfor­mance by decreasing the amount of stray capacitance
at the op amp’s inputs and output. To decrease stray
capacitance, minimize trace lengths by placing exter­nal components as close as possible to the op amp.
Surface-mount components are an excellent choice.

R =

1.8V - 0.1V
240 A

7k to V

L EE

µ

= Ω

MAX4240–MAX4244

Single/Dual/Quad, +1.8V/10µA, SOT23,

Beyond-the-Rails Op Amps

______________________________________________________________________________________ 13

R

ISO

C

L

R

L

MAX4240
MAX4241
MAX4242
MAX4243
MAX4244

AV =

R

L

≈ 1

R

L

+ R

ISO

Figure 8a Using a Resistor to Isolate a Capacitive Load from
the Op Amp

50mV/div

IN

OUT

50mV/div

MAX4240-44 fig08b

100µs/div

R

ISO

= NONE, RL = 100kΩ, CL = 700pF

Figure 8b. Pulse Response without Isolating Resistor

50mV/div

IN

OUT

50mV/div

MAX4240-44 fig08c

100µs/div

R

ISO

= 1kΩ, RL = 100kΩ, CL = 700pF

Figure 8c. Pulse Response with Isolating Resistor

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

= VHI- V

LO

VLO= VINx R2 / (R1 + (R1 x R2 / R

HYST

) + R2)

VHI= [(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 VOSof 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.

Single/Dual/Quad, +1.8V/10µA, SOT23,
Beyond-the-Rails Op Amps

14 ______________________________________________________________________________________

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

Figure 10. Hysteresis Comparator Circuit

10,000

10

0 20 3010 100

100

1000

MAX4240-44 fig09

V

OD

(mV)

t

PD

(µs)

40 50 60 70 80

90

tPD-; V

CC

= +5V

tPD+; V

CC

= +1.8V

tPD-; V

CC

= +1.8V

tPD+; V

CC

= +5V

Figure 9. Propagation Delay vs. Input Overdrive

MAX4240–MAX4244

Single/Dual/Quad, +1.8V/10µA, SOT23,

Beyond-the-Rails Op Amps

______________________________________________________________________________________ 15

_____________________________________________Pin Configurations (continued)

OUT

N.C.V

EE

1
2

87SHDN

V

CC

IN-

IN+

N.C.

SO/µMAX

TOP VIEW

3

4

6

5

MAX4241

INB-

INB+V

EE

1
2

87V

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

Figure 11. Current Monitor for a 2-Cell Battery Stack

MAX4240/MAX4241

TRANSISTOR COUNT: 234

MAX4242/MAX4243

TRANSISTOR COUNT: 466

MAX4244

TRANSISTOR COUNT: 932
SUBSTRATE CONNECTED TO V

EE

___________________Chip Information

I

LOAD

R1

R2

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

© 1998 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

P

D

E

F

W

P

2

P

0

D

1

A

0

B

0

K

0

t

±0.102
±0.102

A

0

B

0

D

D

1

3.200

3.099

1.499

0.991

±0.102
±0.051
±0.102
±0.102

1.753

3.505

1.397

3.988

E
F
K

0

P

+0.102
+0.000

NOTE: DIMENSIONS ARE IN MM.
AND FOLLOW EIA481-1 STANDARD.

+0.305

-0.102

+0.254
+0.000

P

0

3.988 ±0.102

P

0

10 40.005 ±0.203

P

2

2.007 ±0.051

t 0.254 ±0.127

W 8.001

5 SOT23-5

________________________________________________________Package Information

__________________________________________________Tape-and-Reel Information

SOT5L.EPS