Texas Instruments LMP7731 User Manual

LMP7731

LMP7731 2.9 nV/sqrt(Hz) Low Noise, Precision, RRIO Amplifier

Literature Number: SNOSAT6D

LMP7731

May 20, 2009

2.9 nV/sqrt(Hz) Low Noise, Precision, RRIO Amplifier

General Description

The LMP7731 is a single, low noise, rail-to-rail input and out­put, low voltage amplifier. The LMP7731 is part of the LMP

®

precision amplifier family and is ideal for precision and low
noise applications with low voltage requirements.

This operational amplifier offers low voltage noise of 2.9 nV/

√Hz with a 1/f corner of only 3 Hz. The LMP7731 has bipolar

input stages with a bias current of only 1.5 nA. This low input
bias current, complemented by the very low level of voltage
noise, makes the LMP7731 an excellent choice for photom­etry applications.

The LMP7731 provides a wide GBW of 22 MHz while con­suming only 2 mA of current. This high gain bandwidth along
with the high open loop gain of 130 dB enables accurate sig­nal conditioning in applications with high closed loop gain
requirements.

The LMP7731 has a supply voltage range of 1.8V to 5.5V,
making it an ideal choice for battery operated portable appli­cations.

The LMP7731 is offered in the space saving 5-Pin SOT-23
and 8-Pin SOIC packages.

Features

(Typical values, TA = 25°C, VS = 5V)

■

Input voltage noise

—

f = 3 Hz 3.3 nV/√Hz

—

f = 1 kHz 2.9 nV/√Hz

■

CMRR 130 dB

■

Open loop gain 130 dB

■

GBW 22 MHz

■

Slew rate 2.4 V/µs

■

THD @ f = 10 kHz, AV = +1, RL = 2 kΩ 0.001%

■

Supply current per channel 2.2 mA

■

Supply voltage range 1.8V to 5.5V

■

Operating temperature range −40°C to 125°C

■

Input bias current ±1.5 nA

■

RRIO

Applications

■

Gas analysis instruments

■

Photometric instrumentation

■

Medical instrumentation

Typical Performance Characteristics

Input Voltage Noise vs. Frequency

20175261

Input Current Noise vs. Frequency

20175262

LMP® is a registered trademark of National Semiconductor Corporation.

© 2009 National Semiconductor Corporation 201752 www.national.com

LMP7731 2.9 nV/sqrt(Hz) Low Noise, Precision, RRIO Amplifier

Absolute Maximum Ratings (Note 1)

If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.

ESD Tolerance (Note 2)
Human Body Model
Inputs pins only 2000V
All other pins 2000V
Machine Model 200V
Charge Device Model 1000V
VIN Differential

±2V

Supply Voltage (VS = V+ – V−)

6.0V

Storage Temperature Range −65°C to 150°C
Junction Temperature (Note 3) +150°C max
Soldering Information
Infrared or Convection (20 sec) 235°C
Wave Soldering Lead Temp. (10 sec) 260°C

Operating Ratings (Note 1)

Temperature Range −40°C to 125°C
Supply Voltage (VS = V+ – V–)

1.8V to 5.5V

Package Thermal Resistance (θJA)

5-Pin SOT-23 265°C/W
8-Pin SOIC 190°C/W

2.5V Electrical Characteristics (Note 4)

Unless otherwise specified, all limits are guaranteed for TA = 25°C, V+ = 2.5V, V− = 0V, VCM = V+/2, RL >10 kΩ to V+/2. Bold­face limits apply at the temperature extremes.

Symbol Parameter Conditions

Min

(Note 6)

Typ

(Note 5)

Max

(Note 6)

Units

V

OS

Input Offset Voltage
(Note 7)

VCM = 2.0V

±9

±500

±600

μV

VCM = 0.5V

±9

±500

±600

TCV

OS

Input Offset Voltage Temperature Drift

VCM = 2.0V ±0.5 ±5.5

μV/°C

VCM = 0.5V ±0.2 ±5.5

I

B

Input Bias Current

VCM = 2.0V

±1

±30

±45

nA

VCM = 0.5V

±12

±50

±75

I

OS

Input Offset Current

VCM = 2.0V

±1

±50

±75

nA

VCM = 0.5V

±11

±60

±80

TCI

OS

Input Offset Current Drift VCM = 0.5V and VCM = 2.0V 0.0474 nA/°C

CMRR Common Mode Rejection Ratio

0.15V ≤ VCM ≤ 0.7V

0.23V ≤ VCM ≤ 0.7V

101

89

120

dB

1.5V ≤ VCM ≤ 2.35V

1.5V ≤ VCM ≤ 2.27V

105

99

129

PSRR Power Supply Rejection Ratio

2.5V ≤ V+ ≤ 5V

111

105

129

dB

1.8V ≤ V+ ≤ 5.5V

117

CMVR Common Mode Voltage Range

Large Signal CMRR ≥ 80 dB

0 2.5

V

A

VOL

Open Loop Voltage Gain

RL = 10 kΩ to V+/2
V

OUT

= 0.5V to 2.0V

112

104

130

dB

RL = 2 kΩ to V+/2
V

OUT

= 0.5V to 2.0V

109

90

119

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LMP7731

Symbol Parameter Conditions

Min

(Note 6)

Typ

(Note 5)

Max

(Note 6)

Units

V

OUT

Output Voltage Swing High

RL = 10 kΩ to V+/2

4

50

75

mV from

either rail

RL = 2 kΩ to V+/2

13

50

75

Output Voltage Swing Low

RL = 10 kΩ to V+/2

6

50

75

RL = 2 kΩ to V+/2

9

50

75

I

OUT

Output Current

Sourcing, V

OUT

= V+/2

VIN (diff) = 100 mV

22

12

31

mA

Sinking, V

OUT

= V+/2

VIN (diff) = −100 mV

15

10

44

I

S

Supply Current
(Per Channel)

VCM = 2.0V

2.0 2.7

3.4

mA

VCM = 0.5V

2.3 3.1

3.9

SR Slew Rate

AV = +1, CL = 10 pF, RL = 10 kΩ to V+/2,
VO = 2 V

PP

2.4

V/μs

GBW Gain Bandwidth

CL = 20 pF, RL = 10 kΩ to V+/2

21 MHz

G

M

Gain Margin

CL = 20 pF, RL = 10 kΩ to V+/2

14 dB

Φ

M

Phase Margin

CL = 20 pF, RL = 10 kΩ to V+/2

60 deg

R

IN

Input Resistance

Differential Mode 38

kΩ

Common Mode 151

MΩ

THD+N Total Harmonic Distortion + Noise AV = 1, f = 1 kHz, Amplitude = 1V 0.002 %

e

n

Input Referred Voltage Noise Density

f = 1 kHz, VCM = 2.0V 3

nV/

f = 1 kHz, VCM = 0.5V 3

Input Voltage Noise 0.1 Hz to 10 Hz 75 nV

PP

i

n

Input Referred Current Noise Density

f = 1 kHz, VCM = 2.0V 1.1

pA/

f = 1 kHz, VCM = 0.5V 2.3

3.3V Electrical Characteristics (Note 4)

Unless otherwise specified, all limits are guaranteed for TA = 25°C, V+ = 3.3V, V− = 0V, VCM = V+/2, RL > 10 kΩ to V+/2. Bold­face limits apply at the temperature extremes.

Symbol Parameter Conditions

Min

(Note 6)

Typ

(Note 5)

Max

(Note 6)

Units

V

OS

Input Offset Voltage
(Note 7)

VCM = 2.5V

±6

±500

±600

μV

VCM = 0.5V

±6

±500

±600

TCV

OS

Input Offset Voltage Temperature Drift

VCM = 2.5V ±0.5 ±5.5

μV/°C

VCM = 0.5V ±0.2 ±5.5

I

B

Input Bias Current

VCM = 2.5V

±1.5

±30

±45

nA

VCM = 0.5V

±13

±50

±77

I

OS

Input Offset Current

VCM = 2.5V

±1

±50

±70

nA

VCM = 0.5V

±11

±60

±80

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LMP7731

Symbol Parameter Conditions

Min

(Note 6)

Typ

(Note 5)

Max

(Note 6)

Units

TCI

OS

Input Offset Current Drift VCM = 0.5V and VCM = 2.5V

0.048 nA/°C

CMRR Common Mode Rejection Ratio

0.15V ≤ VCM ≤ 0.7V

0.23V ≤ VCM ≤ 0.7V

101

89

120

dB

1.5V ≤ VCM ≤ 3.15V

1.5V ≤ VCM ≤ 3.07V

105

99

130

PSRR Power Supply Rejection Ratio

2.5V ≤ V+ ≤ 5.0V

111

105

129

dB

1.8V ≤ V+ ≤ 5.5V

117

CMVR Common Mode Voltage Range

Large Signal CMRR ≥ 80 dB

0 3.3

V

A

VOL

Open Loop Voltage Gain

RL = 10 kΩ to V+/2
V

OUT

= 0.5V to 2.8V

112

104

130

dB

RL = 2 kΩ to V+/2
V

OUT

= 0.5V to 2.8V

110

92

119

V

OUT

Output Voltage Swing High

RL = 10 kΩ to V+/2

5

50

75

mV from

either rail

RL = 2 kΩ to V+/2

14

50

75

Output Voltage Swing Low

RL = 10 kΩ to V+/2

9

50

75

RL = 2 kΩ to V+/2

13

50

75

I

OUT

Output Current

Sourcing, V

OUT

= V+/2

VIN (diff) = 100 mV

28

22

45

mA

Sinking, V

OUT

= V+/2

VIN (diff) = -100 mV

25

20

48

I

S

Supply Current
(Per Channel)

VCM = 2.5V

2.1

2.8

3.5

mA

VCM = 0.5V

2.4

3.2

4.0

SR Slew Rate

AV = +1, CL = 10 pF, RL = 10 kΩ to V+/2,
V

OUT

= 2 V

PP

2.4

V/μs

GBW Gain Bandwidth

CL = 20 pF, RL = 10 kΩ to V+/2

22 MHz

G

M

Gain Margin

CL = 20 pF, RL = 10 kΩ to V+/2

14 dB

Φ

M

Phase Margin

CL = 20 pF, RL = 10 kΩ to V+/2

62 deg

R

IN

Input Resistance

Differential Mode 38

kΩ

Common Mode 151

MΩ

THD+N Total Harmonic Distortion + Noise AV = 1, f = 1 kHz, Amplitude = 1V, 0.002 %

e

n

Input Referred Voltage Noise Density

f = 1 kHz, VCM = 2.5V 2.9

nV/

f = 1 kHz, VCM = 0.5V 2.9

Input Voltage Noise 0.1 Hz to 10 Hz 65 nV

PP

i

n

Input Referred Current Noise Density

f = 1 kHz, VCM = 2.5V 1.1

pA/

f = 1 kHz, VCM = 0.5V 2.1

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LMP7731

5V Electrical Characteristics (Note 4)

Unless otherwise specified, all limits are guaranteed for TA = 25°C, V+ = 5V, V− = 0V, VCM = V+/2, RL > 10 kΩ to V+/2. Boldface
limits apply at the temperature extremes.

Symbol Parameter Conditions

Min

(Note 6)

Typ

(Note 5)

Max

(Note 6)

Units

V

OS

Input Offset Voltage
(Note 7)

VCM = 4.5V

±6

±500

±600

μV

VCM = 0.5V

±6

±500

±600

TCV

OS

Input Offset Voltage Temperature Drift

VCM = 4.5V ±0.5 ±5.5

μV/°C

VCM = 0.5V ±0.2 ±5.5

I

B

Input Bias Current

VCM = 4.5V

±1.5

±30

±50

nA

VCM = 0.5V

±14

±50

±85

I

OS

Input Offset Current

VCM = 4.5V

±1

±50

±70

nA

VCM = 0.5V

±11

±65

±80

TCI

OS

Input Offset Current Drift VCM = 0.5V and VCM = 4.5V 0.0482 nA/°C

CMRR Common Mode Rejection Ratio

0.15V ≤ VCM ≤ 0.7V

0.23V ≤ VCM ≤ 0.7V

101

89

120

dB

1.5V ≤ VCM ≤ 4.85V

1.5V ≤ VCM ≤ 4.77V

105

99

130

PSRR Power Supply Rejection Ratio

2.5V ≤ V+ ≤ 5V

111

105

129

dB

1.8V ≤ V+ ≤ 5.5V

117

CMVR Common Mode Voltage Range

Large Signal CMRR ≥ 80 dB

0 5

V

A

VOL

Open Loop Voltage Gain

RL = 10 kΩ to V+/2
V

OUT

= 0.5V to 4.5V

112

104

130

dB

RL = 2 kΩ to V+/2
V

OUT

= 0.5V to 4.5V

110

94

119

V

OUT

Output Voltage Swing High

RL = 10 kΩ to V+/2

8

50

75

mV from

either rail

RL = 2 kΩ to V+/2

24

50

75

Output Voltage Swing Low

RL = 10 kΩ to V+/2

9

50

75

RL = 2 kΩ to V+/2

23

50

75

I

OUT

Output Current

Sourcing, V

OUT

= V+/2

VIN (diff) = 100 mV

33

27

47

mA

Sinking, V

OUT

= V+/2

VIN (diff) = -100 mV

30

25

49

I

S

Supply Current
(Per Channel)

VCM = 4.5V

2.2

3.0

3.7

mA

VCM = 0.5V

2.5

3.4

4.2

SR Slew Rate

AV = +1, CL = 10 pF, RL = 10 kΩ to V+/2,
V

OUT

= 2 V

PP

2.4

V/μs

GBW Gain Bandwidth

CL = 20 pF, RL = 10 kΩ to V+/2

22 MHz

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LMP7731