LMP7704MAX [TI]

LMP7701/LMP7702/LMP7704 Precision, CMOS Input, RRIO, Wide Supply Range Amplifiers; LMP7701 / LMP7702 / LMP7704高精度, CMOS输入, RRIO ,宽电源范围放大器
LMP7704MAX
型号: LMP7704MAX
厂家: TEXAS INSTRUMENTS    TEXAS INSTRUMENTS
描述:

LMP7701/LMP7702/LMP7704 Precision, CMOS Input, RRIO, Wide Supply Range Amplifiers
LMP7701 / LMP7702 / LMP7704高精度, CMOS输入, RRIO ,宽电源范围放大器

放大器
文件: 总35页 (文件大小:1221K)
中文:  中文翻译
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LMP7701, LMP7702, LMP7704  
www.ti.com  
SNOSAI9H SEPTEMBER 2005REVISED MARCH 2013  
LMP7701/LMP7702/LMP7704 Precision, CMOS Input, RRIO, Wide Supply Range Amplifiers  
Check for Samples: LMP7701, LMP7702, LMP7704  
1
FEATURES  
DESCRIPTION  
The LMP7701/LMP7702/LMP7704 are single, dual,  
and quad low offset voltage, rail-to-rail input and  
output precision amplifiers each with a CMOS input  
23  
Unless Otherwise Noted,  
Typical Values at VS = 5V  
Input Offset Voltage (LMP7701): ±200 µV  
(max)  
stage and  
a wide supply voltage range. The  
LMP7701/LMP7702/LMP7704 are part of the LMP™  
precision amplifier family and are ideal for sensor  
interface and other instrumentation applications.  
Input Offset Voltage (LMP7702/LMP7704):  
±220 µV (max)  
Input Bias Current: ±200 fA  
Input Bias Current: ±200 fA  
Input Voltage Noise: 9 nV/Hz  
CMRR: 130 dB  
The specified low offset voltage of less than ±200 µV  
along with the specified low input bias current of less  
than ±1 pA make the LMP7701 ideal for precision  
applications. The LMP7701/LMP7702/LMP7704 are  
built utilizing VIP50 technology, which allows the  
combination of a CMOS input stage and a 12V  
common mode and supply voltage range. This makes  
the LMP7701/LMP7702/LMP7704 great choices in  
many applications where conventional CMOS parts  
cannot operate under the desired voltage conditions.  
Open Loop Gain: 130 dB  
Temperature Range: 40°C to 125°C  
Unity Gain Bandwidth: 2.5 MHz  
Supply Current (LMP7701): 715 µA  
Supply Current (LMP7702): 1.5 mA  
Supply Current (LMP7704): 2.9 mA  
Supply Voltage Range: 2.7V to 12V  
Rail-to-Rail Input and Output  
The LMP7701/LMP7702/LMP7704 each have a rail-  
to-rail input stage that significantly reduces the CMRR  
glitch commonly associated with rail-to-rail input  
amplifiers. This is achieved by trimming both sides of  
the complimentary input stage, thereby reducing the  
difference between the NMOS and PMOS offsets.  
The output of the LMP7701/LMP7702/LMP7704  
swings within 40 mV of either rail to maximize the  
signal dynamic range in applications requiring low  
supply voltage.  
APPLICATIONS  
High Impedance Sensor Interface  
Battery Powered Instrumentation  
High Gain Amplifiers  
DAC Buffer  
The LMP7701 is offered in the space saving 5-Pin  
SOT-23 and 8-Pin SOIC package. The LMP7702 is  
offered in the 8-Pin SOIC and 8-Pin VSSOP package.  
The quad LMP7704 is offered in the 14-Pin SOIC and  
14-Pin TSSOP package. These small packages are  
ideal solutions for area constrained PC boards and  
portable electronics.  
Instrumentation Amplifier  
Active Filters  
These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam  
during storage or handling to prevent electrostatic damage to the MOS gates.  
1
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of  
Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.  
2
3
LMP is a trademark of Texas Instruments.  
All other trademarks are the property of their respective owners.  
PRODUCTION DATA information is current as of publication date.  
Products conform to specifications per the terms of the Texas  
Instruments standard warranty. Production processing does not  
necessarily include testing of all parameters.  
Copyright © 2005–2013, Texas Instruments Incorporated  
LMP7701, LMP7702, LMP7704  
SNOSAI9H SEPTEMBER 2005REVISED MARCH 2013  
www.ti.com  
TYPICAL APPLICATION  
R
R
V
1
+
V
-
R
S
I = (V2 œ V1)  
A
1
RS  
+
-
V
+
V
Z
LOAD  
-
R
R
V
2
A
2
+
-
V
Figure 1. Precision Current Source  
(1)(2)  
Absolute Maximum Ratings  
ESD Tolerance  
(3)  
Human Body Model  
Machine Model  
2000V  
200V  
Charge-Device Model  
1000V  
VIN Differential  
±300 mV  
Supply Voltage (VS = V+ – V)  
Voltage at Input/Output Pins  
Input Current  
13.2V  
V++ 0.3V, V0.3V  
10 mA  
Storage Temperature Range  
65°C to +150°C  
+150°C  
(4)  
Junction Temperature  
Soldering Information  
Infrared or Convection (20 sec)  
235°C  
Wave Soldering Lead Temp. (10 sec)  
260°C  
(1) Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for  
which the device is intended to be functional, but specific performance is not ensured. For ensured specifications and the test  
conditions, see the Electrical Characteristics Tables.  
(2) If Military/Aerospace specified devices are required, please contact the TI Sales Office/ Distributors for availability and specifications.  
(3) Human Body Model, applicable std. MIL-STD-883, Method 3015.7. Machine Model, applicable std. JESD22-A115-A (ESD MM std. of  
JEDEC) Field-Induced Charge-Device Model, applicable std. JESD22-C101-C (ESD FICDM std. of JEDEC).  
(4) The maximum power dissipation is a function of TJ(MAX), θJA. The maximum allowable power dissipation at any ambient temperature is  
PD = (TJ(MAX) – TA)/ θJA. All numbers apply for packages soldered directly onto a PC Board.  
2
Submit Documentation Feedback  
Copyright © 2005–2013, Texas Instruments Incorporated  
Product Folder Links: LMP7701 LMP7702 LMP7704  
LMP7701, LMP7702, LMP7704  
www.ti.com  
SNOSAI9H SEPTEMBER 2005REVISED MARCH 2013  
(1)  
Operating Ratings  
Temperature Range  
(2)  
40°C to +125°C  
2.7V to 12V  
265°C/W  
Supply Voltage (VS = V+ – V)  
(2)  
Package Thermal Resistance (θJA  
)
5-Pin SOT-23  
8-Pin SOIC  
190°C/W  
8-Pin VSSOP  
14-Pin SOIC  
14-Pin TSSOP  
235°C/W  
145°C/W  
122°C/W  
(1) Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for  
which the device is intended to be functional, but specific performance is not ensured. For ensured specifications and the test  
conditions, see the Electrical Characteristics Tables.  
(2) The maximum power dissipation is a function of TJ(MAX), θJA. The maximum allowable power dissipation at any ambient temperature is  
PD = (TJ(MAX) – TA)/ θJA. All numbers apply for packages soldered directly onto a PC Board.  
(1)  
3V Electrical Characteristics  
Unless otherwise specified, all limits are ensured for TA = 25°C, V+ = 3V, V= 0V, VCM = V+/2, and RL > 10 kto V+/2.  
Boldface limits apply at the temperature extremes.  
(2)  
(3)  
(2)  
Parameter  
Test Conditions  
Min  
Typ  
±37  
Max  
Units  
μV  
VOS  
Input Offset Voltage  
LMP7701  
±200  
±500  
LMP7702/LMP7704  
±56  
±220  
±520  
(4)  
TCVOS  
IB  
Input Offset Voltage Temperature Drift  
Input Bias Current  
±1  
±5  
μV/°C  
pA  
(4) (5)  
±0.2  
±1  
±50  
40°C TA 85°C  
(4) (5)  
±0.2  
±1  
40°C TA 125°C  
±400  
IOS  
Input Offset Current  
40  
fA  
CMRR  
Common Mode Rejection Ratio  
0V VCM 3V  
86  
130  
LMP7701  
80  
dB  
0V VCM 3V  
LMP7702/LMP7704  
2.7V V+ 12V, Vo = V+/2  
84  
78  
130  
98  
PSRR  
CMVR  
AVOL  
Power Supply Rejection Ratio  
Common Mode Voltage Range  
Open Loop Voltage Gain  
86  
82  
dB  
V
CMRR 80 dB  
CMRR 77 dB  
–0.2  
–0.2  
3.2  
3.2  
RL = 2 k(LMP7701)  
VO = 0.3V to 2.7V  
100  
96  
114  
114  
124  
RL = 2 k(LMP7702/LMP7704)  
VO = 0.3V to 2.7V  
100  
94  
dB  
RL = 10 kΩ  
100  
VO = 0.2V to 2.8V  
96  
(1) Electrical Table values apply only for factory testing conditions at the temperature indicated. Factory testing conditions result in very  
limited self-heating of the device such that TJ = TA. No specification of parametric performance is indicated in the electrical tables under  
conditions of internal self-heating where TJ > TA.  
(2) Limits are 100% production tested at 25°C. Limits over the operating temperature range are specified through correlations using the  
Statistical Quality Control (SQC) method.  
(3) Typical values represent the most likely parametric norm as determined at the time of characterization. Actual typical values may vary  
over time and will also depend on the application and configuration. The typical values are not tested and are not specified on shipped  
production material.  
(4) This parameter is specified by design and/or characterization and is not tested in production.  
(5) Positive current corresponds to current flowing into the device.  
Copyright © 2005–2013, Texas Instruments Incorporated  
Submit Documentation Feedback  
3
Product Folder Links: LMP7701 LMP7702 LMP7704  
LMP7701, LMP7702, LMP7704  
SNOSAI9H SEPTEMBER 2005REVISED MARCH 2013  
www.ti.com  
3V Electrical Characteristics (1) (continued)  
Unless otherwise specified, all limits are ensured for TA = 25°C, V+ = 3V, V= 0V, VCM = V+/2, and RL > 10 kto V+/2.  
Boldface limits apply at the temperature extremes.  
(2)  
(3)  
(2)  
Parameter  
Test Conditions  
RL = 2 kto V+/2  
Min  
Typ  
40  
Max  
Units  
VOUT  
Output Voltage Swing High  
80  
LMP7701  
120  
RL = 2 kto V+/2  
LMP7702/LMP7704  
RL = 10 kto V+/2  
LMP7701  
RL = 10 kto V+/2  
LMP7702/LMP7704  
RL = 2 kto V+/2  
LMP7701  
RL = 2 kto V+/2  
LMP7702/LMP7704  
RL = 10 kto V+/2  
LMP7701  
RL = 10 kto V+/2  
LMP7702/LMP7704  
Sourcing VO = V+/2  
VIN = 100 mV  
Sinking VO = V+/2  
40  
30  
35  
40  
45  
20  
20  
42  
42  
42  
80  
150  
mV  
from V+  
40  
60  
50  
100  
Output Voltage Swing Low  
60  
80  
100  
170  
mV  
mA  
40  
50  
50  
90  
(6) (7)  
IOUT  
Output Current  
25  
15  
25  
20  
VIN = 100 mV (LMP7701)  
Sinking VO = V+/2  
25  
VIN = 100 mV (LMP7702/LMP7704)  
15  
IS  
Supply Current  
LMP7701  
LMP7702  
LMP7704  
0.670  
1.4  
1.0  
1.2  
1.8  
2.1  
mA  
2.9  
3.5  
4.5  
(8)  
SR  
Slew Rate  
AV = +1, VO = 2 VPP  
10% to 90%  
0.9  
V/μs  
GBW  
THD+N  
en  
Gain Bandwidth  
2.5  
0.02  
9
MHz  
%
Total Harmonic Distortion + Noise  
Input Referred Voltage Noise Density  
Input Referred Current Noise Density  
f = 1 kHz, AV = 1, R.L = 10 kΩ  
f = 1 kHz  
nV/Hz  
fA/Hz  
in  
f = 100 kHz  
1
(6) The maximum power dissipation is a function of TJ(MAX), θJA. The maximum allowable power dissipation at any ambient temperature is  
PD = (TJ(MAX) – TA)/ θJA. All numbers apply for packages soldered directly onto a PC Board.  
(7) The short circuit test is a momentary test.  
(8) The number specified is the slower of positive and negative slew rates.  
4
Submit Documentation Feedback  
Copyright © 2005–2013, Texas Instruments Incorporated  
Product Folder Links: LMP7701 LMP7702 LMP7704  
 
LMP7701, LMP7702, LMP7704  
www.ti.com  
SNOSAI9H SEPTEMBER 2005REVISED MARCH 2013  
(1)  
5V Electrical Characteristics  
Unless otherwise specified, all limits are ensured for TA = 25°C, V+ = 5V, V= 0V, VCM = V+/2, and RL > 10 kto V+/2.  
Boldface limits apply at the temperature extremes.  
(2)  
(3)  
(2)  
Parameter  
Test Conditions  
Min  
Typ  
±37  
Max  
Units  
μV  
VOS  
Input Offset Voltage  
LMP7701  
±200  
±500  
LMP7702/LMP7704  
±32  
±220  
±520  
(4)  
TCVOS  
IB  
Input Offset Voltage Temperature Drift  
Input Bias Current  
±1  
±5  
μV/°C  
pA  
(4) (5)  
±0.2  
±1  
±50  
40°C TA 85°C  
(4) (5)  
±0.2  
±1  
40°C TA 125°C  
±400  
IOS  
Input Offset Current  
40  
fA  
CMRR  
Common Mode Rejection Ratio  
0V VCM 5V  
88  
130  
LMP7701  
83  
dB  
0V VCM 5V  
LMP7702/LMP7704  
2.7V V+ 12V, VO = V+/2  
86  
81  
130  
100  
PSRR  
CMVR  
AVOL  
Power Supply Rejection Ratio  
Common Mode Voltage Range  
Open Loop Voltage Gain  
86  
82  
dB  
V
CMRR 80 dB  
CMRR 78 dB  
–0.2  
–0.2  
5.2  
5.2  
RL = 2 k(LMP7701)  
VO = 0.3V to 4.7V  
100  
96  
119  
119  
130  
60  
RL = 2 k(LMP7702/LMP7704)  
VO = 0.3V to 4.7V  
100  
94  
dB  
RL = 10 kΩ  
VO = 0.2V to 4.8V  
RL = 2 kto V+/2  
100  
96  
VOUT  
Output Voltage Swing High  
110  
LMP7701  
130  
RL = 2 kto V+/2  
60  
120  
LMP7702/LMP7704  
RL = 10 kto V+/2  
200  
mV  
from V+  
40  
50  
LMP7701  
70  
RL = 10 kto V+/2  
40  
60  
LMP7702/LMP7704  
120  
Output Voltage Swing Low  
RL = 2 kto V+/2  
50  
80  
LMP7701  
90  
RL = 2 kto V+/2  
50  
120  
LMP7702/LMP7704  
RL = 10 kto V+/2  
190  
mV  
30  
40  
LMP7701  
50  
RL = 10 kto V+/2  
30  
50  
LMP7702/LMP7704  
100  
(1) Electrical Table values apply only for factory testing conditions at the temperature indicated. Factory testing conditions result in very  
limited self-heating of the device such that TJ = TA. No specification of parametric performance is indicated in the electrical tables under  
conditions of internal self-heating where TJ > TA.  
(2) Limits are 100% production tested at 25°C. Limits over the operating temperature range are specified through correlations using the  
Statistical Quality Control (SQC) method.  
(3) Typical values represent the most likely parametric norm as determined at the time of characterization. Actual typical values may vary  
over time and will also depend on the application and configuration. The typical values are not tested and are not ensured on shipped  
production material.  
(4) This parameter is specified by design and/or characterization and is not tested in production.  
(5) Positive current corresponds to current flowing into the device.  
Copyright © 2005–2013, Texas Instruments Incorporated  
Submit Documentation Feedback  
5
Product Folder Links: LMP7701 LMP7702 LMP7704  
LMP7701, LMP7702, LMP7704  
SNOSAI9H SEPTEMBER 2005REVISED MARCH 2013  
www.ti.com  
5V Electrical Characteristics (1) (continued)  
Unless otherwise specified, all limits are ensured for TA = 25°C, V+ = 5V, V= 0V, VCM = V+/2, and RL > 10 kto V+/2.  
Boldface limits apply at the temperature extremes.  
(2)  
(3)  
(2)  
Parameter  
Test Conditions  
Sourcing VO = V+/2  
Min  
Typ  
66  
Max  
Units  
(6) (7)  
IOUT  
Output Current  
40  
VIN = 100 mV (LMP7701)  
28  
Sourcing VO = V+/2  
VIN = 100 mV (LMP7702/LMP7704)  
Sinking VO = V+/2  
VIN = 100 mV (LMP7701)  
38  
25  
66  
76  
76  
mA  
40  
28  
Sinking VO = V+/2  
40  
VIN = 100 mV (LMP7702/LMP7704)  
23  
IS  
Supply Current  
LMP7701  
LMP7702  
LMP7704  
0.715  
1.5  
1.0  
1.2  
1.9  
2.2  
mA  
2.9  
3.7  
4.6  
(8)  
SR  
Slew Rate  
AV = +1, VO = 4 VPP  
10% to 90%  
1.0  
V/μs  
GBW  
THD+N  
en  
Gain Bandwidth  
2.5  
0.02  
9
MHz  
%
Total Harmonic Distortion + Noise  
Input Referred Voltage Noise Density  
Input Referred Current Noise Density  
f = 1 kHz, AV = 1, RL = 10 kΩ  
f = 1 kHz  
nV/Hz  
fA/Hz  
in  
f = 100 kHz  
1
(6) The maximum power dissipation is a function of TJ(MAX), θJA. The maximum allowable power dissipation at any ambient temperature is  
PD = (TJ(MAX) – TA)/ θJA. All numbers apply for packages soldered directly onto a PC Board.  
(7) The short circuit test is a momentary test.  
(8) The number specified is the slower of positive and negative slew rates.  
(1)  
±5V Electrical Characteristics  
Unless otherwise specified, all limits are ensured for TA = 25°C, V+ = 5V, V= 5V, VCM = 0V, and RL > 10 kto 0V.  
Boldface limits apply at the temperature extremes.  
(2)  
(3)  
(2)  
Parameter  
Test Conditions  
Min  
Typ  
±37  
Max  
Units  
μV  
VOS  
Input Offset Voltage  
LMP7701  
±200  
±500  
LMP7702/LMP7704  
±37  
±220  
±520  
(4)  
TCVOS  
IB  
Input Offset Voltage Temperature Drift  
Input Bias Current  
±1  
±5  
μV/°C  
pA  
(4) (5)  
±0.2  
1
±50  
40°C TA 85°C  
(4) (5)  
±0.2  
1
40°C TA 125°C  
±400  
IOS  
Input Offset Current  
40  
fA  
CMRR  
Common Mode Rejection Ratio  
5V VCM 5V  
92  
138  
LMP7701  
88  
dB  
5V VCM 5V  
90  
138  
LMP7702/LMP7704  
86  
(1) Electrical Table values apply only for factory testing conditions at the temperature indicated. Factory testing conditions result in very  
limited self-heating of the device such that TJ = TA. No specification of parametric performance is indicated in the electrical tables under  
conditions of internal self-heating where TJ > TA.  
(2) Limits are 100% production tested at 25°C. Limits over the operating temperature range are specified through correlations using the  
Statistical Quality Control (SQC) method.  
(3) Typical values represent the most likely parametric norm as determined at the time of characterization. Actual typical values may vary  
over time and will also depend on the application and configuration. The typical values are not tested and are not ensured on shipped  
production material.  
(4) This parameter is specified by design and/or characterization and is not tested in production.  
(5) Positive current corresponds to current flowing into the device.  
6
Submit Documentation Feedback  
Copyright © 2005–2013, Texas Instruments Incorporated  
Product Folder Links: LMP7701 LMP7702 LMP7704  
 
LMP7701, LMP7702, LMP7704  
www.ti.com  
SNOSAI9H SEPTEMBER 2005REVISED MARCH 2013  
±5V Electrical Characteristics (1) (continued)  
Unless otherwise specified, all limits are ensured for TA = 25°C, V+ = 5V, V= 5V, VCM = 0V, and RL > 10 kto 0V.  
Boldface limits apply at the temperature extremes.  
(2)  
(3)  
(2)  
Parameter  
Test Conditions  
2.7V V+ 12V, VO = 0V  
Min  
86  
82  
Typ  
98  
Max  
Units  
PSRR  
CMVR  
AVOL  
Power Supply Rejection Ratio  
dB  
Common Mode Voltage Range  
Open Loop Voltage Gain  
CMRR 80 dB  
CMRR 78 dB  
5.2  
5.2  
5.2  
5.2  
V
RL = 2 k(LMP7701)  
VO = 4.7V to 4.7V  
100  
98  
121  
121  
134  
134  
90  
RL = 2 k(LMP7702/LMP7704)  
VO = 4.7V to 4.7V  
100  
94  
dB  
RL = 10 k(LMP7701)  
VO = 4.8V to 4.8V  
100  
98  
RL = 10 k(LMP7702/LMP7704)  
VO = 4.8V to 4.8V  
100  
97  
VOUT  
Output Voltage Swing High  
RL = 2 kto 0V  
150  
LMP7701  
170  
RL = 2 kto 0V  
90  
180  
LMP7702/LMP7704  
290  
mV  
from V+  
RL = 10 kto 0V  
40  
80  
LMP7701  
100  
RL = 10 kto 0V  
40  
80  
LMP7702/LMP7704  
150  
Output Voltage Swing Low  
RL = 2 kto 0V  
90  
130  
LMP7701  
150  
RL = 2 kto 0V  
90  
180  
LMP7702/LMP7704  
290  
mV  
from V–  
RL = 10 kto 0V  
40  
50  
LMP7701  
60  
RL = 10 kto 0V  
40  
60  
LMP7702/LMP7704  
110  
(6) (7)  
IOUT  
Output Current  
Sourcing VO = 0V  
50  
86  
VIN = 100 mV (LMP7701)  
35  
Sourcing VO = 0V  
VIN = 100 mV (LMP7702/LMP7704)  
48  
33  
86  
mA  
Sinking VO = 0V  
50  
84  
VIN = 100 mV  
35  
IS  
Supply Current  
LMP7701  
LMP7702  
LMP7704  
0.790  
1.7  
3.2  
1.1  
1.1  
1.3  
2.1  
2.5  
mA  
4.2  
5.0  
(8)  
SR  
Slew Rate  
AV = +1, VO = 9 VPP  
10% to 90%  
V/μs  
GBW  
THD+N  
en  
Gain Bandwidth  
2.5  
0.02  
9
MHz  
%
Total Harmonic Distortion + Noise  
Input Referred Voltage Noise Density  
Input Referred Current Noise Density  
f = 1 kHz, AV = 1, RL = 10 kΩ  
f = 1 kHz  
nV/Hz  
fA/Hz  
in  
f = 100 kHz  
1
(6) The maximum power dissipation is a function of TJ(MAX), θJA. The maximum allowable power dissipation at any ambient temperature is  
PD = (TJ(MAX) – TA)/ θJA. All numbers apply for packages soldered directly onto a PC Board.  
(7) The short circuit test is a momentary test.  
(8) The number specified is the slower of positive and negative slew rates.  
Copyright © 2005–2013, Texas Instruments Incorporated  
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CONNECTION DIAGRAMS  
+
1
5
8
1
N/C  
V
N/C  
OUT  
+
2
3
4
7
6
5
V
-IN  
-
2
3
-
V
-
+
OUTPUT  
N/C  
+
+IN  
4
IN-  
IN+  
-
V
Figure 2. 5-Pin SOT-23 (LMP7701)  
Top View  
Figure 3. 8-Pin SOIC (LMP7701)  
Top View  
Figure 4. 8-Pin SOIC/VSSOP (LMP7702)  
Top View  
Figure 5. 14-Pin SOIC/TSSOP (LMP7704)  
Top View  
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Typical Performance Characteristics  
Unless otherwise noted: TA = 25°C, VCM = VS/2, RL > 10 k.  
Offset Voltage Distribution  
TCVOS Distribution  
20  
16  
25  
20  
V
= 3V  
V
T
= 3V  
S
S
-40°C Ç T Ç 125°C  
= 25°C  
A
A
12  
8
15  
10  
5
4
0
0
-200  
-100  
0
100  
200  
-3  
-3  
-3  
-2  
-2  
-2  
-1  
0
1
2
3
3
3
OFFSET VOLTAGE (mV)  
TCV  
(mV/°C)  
OS  
Figure 6.  
Figure 7.  
Offset Voltage Distribution  
TCVOS Distribution  
20  
16  
25  
20  
15  
10  
5
V
T
= 5V  
V
= 5V  
S
S
= 25°C  
-40°C Ç T Ç 125°C  
A
A
12  
8
4
0
0
-200  
-100  
0
100  
200  
-1  
0
1
2
OFFSET VOLTAGE (mV)  
TCV  
(mV/°C)  
OS  
Figure 8.  
Figure 9.  
Offset Voltage Distribution  
TCVOS Distribution  
20  
16  
25  
20  
15  
10  
5
V = 10V  
S
V
= 10V  
= 25°C  
S
-40°C Ç T Ç 125°C  
T
A
A
12  
8
4
0
0
-200  
-100  
0
100  
200  
-1  
0
1
2
OFFSET VOLTAGE (mV)  
TCV  
(mV/°C)  
OS  
Figure 10.  
Figure 11.  
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Typical Performance Characteristics (continued)  
Unless otherwise noted: TA = 25°C, VCM = VS/2, RL > 10 k.  
Offset Voltage  
CMRR  
vs.  
Frequency  
vs.  
Temperature  
200  
0
150  
100  
-20  
V
= 3V  
S
-40  
V
= 3V  
S
V
S
= 5V  
50  
-60  
-80  
0
V
= 10V  
S
-50  
V
S
= 5V  
-100  
-100  
-150  
-200  
V
= 10V  
S
-120  
-140  
-40 -20  
0
20 40 60 80 100 120125  
10k  
1k  
100k  
10  
100  
1M  
TEMPERATURE (°C)  
FREQUENCY (Hz)  
Figure 12.  
Figure 13.  
Offset Voltage  
vs.  
Supply Voltage  
Offset Voltage  
vs.  
VCM  
200  
150  
100  
200  
150  
100  
50  
V
= 3V  
S
-40°C  
-40°C  
25°C  
50  
0
25°C  
0
-50  
-50  
125°C  
-100  
-100  
-150  
-200  
125°C  
-150  
-200  
2
4
6
8
10  
12  
-0.5  
0
0.5  
1.5  
(V)  
2
2.5  
3
3.5  
1
V
CM  
SUPPLY VOLTAGE (V)  
Figure 14.  
Figure 15.  
Offset Voltage  
Offset Voltage  
vs.  
vs.  
VCM  
VCM  
200  
150  
200  
V
S
= 10V  
V
= 5V  
S
150  
100  
100  
-40°C  
25°C  
-40°C  
25°C  
50  
0
50  
0
-50  
-50  
-100  
-150  
-200  
-100  
-150  
125°C  
125°C  
-200  
-1  
0
1
2
3
4
5
6
5
-1  
0
1
2
3
4
6
7
8
9 10 11  
V
CM  
(V)  
V
CM  
(V)  
Figure 16.  
Figure 17.  
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Typical Performance Characteristics (continued)  
Unless otherwise noted: TA = 25°C, VCM = VS/2, RL > 10 k.  
Input Bias Current  
Input Bias Current  
vs.  
vs.  
VCM  
VCM  
300  
200  
100  
200  
V
S
= 3V  
V
S
= 3V  
100  
0
85°C  
-40°C  
0
-100  
-100  
-200  
-200  
-300  
125°C  
25°C  
1.5  
0
0
0
0.5  
1
1.5  
(V)  
2
2.5  
3
0
0.5  
1
2
2.5  
3
V
V
(V)  
CM  
CM  
Figure 18.  
Figure 19.  
Input Bias Current  
Input Bias Current  
vs.  
VCM  
vs.  
VCM  
300  
200  
100  
300  
200  
V
S
= 5V  
V
= 5V  
S
100  
0
85°C  
-40°C  
25°C  
0
-100  
-100  
-200  
-300  
-200  
-300  
125°C  
1
2
3
4
5
0
1
2
3
4
5
V
(V)  
V
CM  
(V)  
CM  
Figure 20.  
Figure 21.  
Input Bias Current  
vs.  
VCM  
Input Bias Current vs. VCM  
500  
300  
200  
V
S
= 10V  
V
S
= 10V  
250  
0
100  
0
85°C  
-40°C  
25°C  
-100  
-250  
-200  
-300  
125°C  
-500  
2
4
6
8
10  
0
2
4
6
8
10  
V
CM  
(V)  
V
CM  
(V)  
Figure 22.  
Figure 23.  
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Typical Performance Characteristics (continued)  
Unless otherwise noted: TA = 25°C, VCM = VS/2, RL > 10 k.  
PSRR vs. Frequency  
Supply Current vs. Supply Voltage (Per Channel)  
120  
1.2  
V
= 10V  
S
V
S
= 5V  
100  
1
125°C  
-40°C  
V
S
= 3V  
25°C  
+PSRR  
0.8  
0.6  
0.4  
80  
60  
V
= 10V  
S
V
= 5V  
S
V
= 3V  
S
40  
20  
0.2  
0
-PSRR  
100k  
0
10k  
10  
100  
1k  
1M  
2
4
6
8
10  
12  
FREQUENCY (Hz)  
SUPPLY VOLTAGE (V)  
Figure 24.  
Figure 25.  
Sinking Current vs. Supply Voltage  
Sourcing Current vs. Supply Voltage  
120  
100  
120  
-40°C  
25°C  
-40°C  
125°C  
100  
25°C  
80  
60  
40  
80  
60  
40  
125°C  
20  
0
20  
0
2
4
6
8
10  
12  
2
4
6
8
10  
12  
SUPPLY VOLTAGE (V)  
SUPPLY VOLTAGE (V)  
Figure 26.  
Figure 27.  
Output Voltage vs. Output Current  
Slew Rate vs. Supply Voltage  
+
1.5  
1.4  
1.3  
1.2  
1.1  
1
V
A
V
= +1  
T
A
= -40°C, 25°C, 125C  
V
= 2 V  
+
IN  
PP  
(V ) -1  
R
C
= 10 kW  
L
L
FALLING EDGE  
RISING EDGE  
= 10 pF  
+
(V ) -2  
3V  
ö
ö
0.9  
0.8  
0.7  
0.6  
0.5  
2
1
0
V
= 3V, 5V, 10V  
S
0
20  
40  
60  
80  
100  
2
4
6
8
10  
12  
OUTPUT CURRENT (mA)  
SUPPLY VOLTAGE (V)  
Figure 28.  
Figure 29.  
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Typical Performance Characteristics (continued)  
Unless otherwise noted: TA = 25°C, VCM = VS/2, RL > 10 k.  
Open Loop Frequency Response  
Open Loop Frequency Response  
100  
80  
60  
40  
20  
0
225  
180  
135  
90  
100  
80  
60  
40  
20  
0
225  
V
= 3V, 5V, 10V  
= 20 pF, 50 pF, 100 pF  
= 10 kW  
S
GAIN  
GAIN  
180  
135  
C
R
L
L
V
= 10V  
S
-40°C  
25°C  
C
= 20 pF 90  
L
PHASE  
PHASE  
45  
0
45  
0
125°C  
125°C  
25°C  
-40°C  
-45  
-90  
-45  
-90  
-20  
-40  
-60  
-20  
-40  
-60  
V
= 5V  
S
C
= 20 pF  
= 10 kW  
V
= 3V  
L
L
S
R
C
= 100 pF  
L
-135  
10M  
100M  
-135  
10M  
100M  
100k  
100  
10k  
1M  
1k  
100k  
100  
10k  
1M  
1k  
FREQUENCY (Hz)  
FREQUENCY (Hz)  
Figure 30.  
Figure 31.  
Large Signal Step Response  
Small Signal Step Response  
V
= 5V  
V
= 5V  
S
S
f = 10 kHz  
f = 10 kHz  
A
V
= +1  
A
V
= +1  
V
V
= 100 mV  
= 10 kW  
= 10 pF  
= 2 V  
IN  
PP  
IN  
PP  
R
R
= 10 kW  
L
L
L
L
C
C
= 10 pF  
10 ms/DIV  
10 ms/DIV  
Figure 32.  
Figure 33.  
Large Signal Step Response  
Small Signal Step Response  
V
= 5V  
V
= 5V  
S
S
f = 10 kHz  
f = 10 kHz  
A
V
= +10  
A
V
= +10  
V
V
= 100 mV  
= 10 kW  
= 10 pF  
= 400 mV  
= 10 kW  
= 10 pF  
IN  
PP  
IN  
PP  
R
R
L
L
L
L
C
C
10 ms/DIV  
10 ms/DIV  
Figure 34.  
Figure 35.  
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Typical Performance Characteristics (continued)  
Unless otherwise noted: TA = 25°C, VCM = VS/2, RL > 10 k.  
Input Voltage Noise vs. Frequency  
Open Loop Gain vs. Output Voltage Swing  
120  
150  
140  
130  
120  
V
= 10V  
S
V
= 5V  
S
100  
80  
R
L
= 10 kW  
110  
100  
90  
V
= 3V  
S
60  
40  
20  
0
V
= 3V  
S
V
= 5V  
S
80  
R
L
= 2 kW  
70  
V
= 10V  
S
60  
500  
1k  
1
10  
100  
10k  
100k  
400  
300  
200  
100  
0
FREQUENCY (Hz)  
OUTPUT SWING FROM RAIL (mV)  
Figure 36.  
Figure 37.  
Output Swing High vs. Supply Voltage  
Output Swing Low vs. Supply Voltage  
50  
50  
40  
30  
20  
10  
0
R
L
= 10 kW  
R
L
= 10 kW  
25°C  
40  
30  
20  
10  
0
125°C  
-40°C  
125°C  
-40°C  
25°C  
2
4
6
8
10  
12  
2
4
6
8
10  
12  
SUPPLY VOLTAGE (V)  
SUPPLY VOLTAGE (V)  
Figure 38.  
Figure 39.  
Output Swing High vs. Supply Voltage  
Output Swing Low vs. Supply Voltage  
100  
80  
60  
40  
20  
0
100  
80  
60  
40  
20  
0
R
= 2 kW  
R
L
= 2 kW  
L
25°C  
25°C  
125°C  
125°C  
-40°C  
-40°C  
2
4
6
8
10  
12  
2
4
6
8
10  
12  
SUPPLY VOLTAGE (V)  
SUPPLY VOLTAGE (V)  
Figure 40.  
Figure 41.  
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Typical Performance Characteristics (continued)  
Unless otherwise noted: TA = 25°C, VCM = VS/2, RL > 10 k.  
THD+N vs. Frequency  
THD+N vs. Output Voltage  
1
1
V
= 5V  
S
V
V
= 5V  
S
f = 1 kHz  
= 4.5 V  
O
PP  
R
= 100 kW  
L
R
= 100 kW  
L
0.1  
0.01  
0.1  
0.01  
A
V
= +10  
A
V
= +10  
A
V
= +1  
A
V
= +1  
0.001  
0.001  
10  
100  
1k  
10k  
100k  
0.001  
0.01  
0.1  
1
10  
V
OUT  
(V)  
FREQUENCY (Hz)  
Figure 42.  
Figure 43.  
Crosstalk Rejection Ratio vs. Frequency (LMP7702/LMP7704)  
140  
V
S
= 12V  
120  
100  
80  
V
= 5V  
S
V
S
= 3V  
60  
40  
100  
1k  
10k  
100k  
1M  
FREQUENCY (Hz)  
Figure 44.  
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APPLICATION INFORMATION  
LMP7701/LMP7702/LMP7704  
The LMP7701/LMP7702/LMP7704 are single, dual, and quad low offset voltage, rail-to-rail input and output  
precision amplifiers each with a CMOS input stage and wide supply voltage range of 2.7V to 12V. The  
LMP7701/LMP7702/LMP7704 have a very low input bias current of only ±200 fA at room temperature.  
The wide supply voltage range of 2.7V to 12V over the extensive temperature range of 40°C to 125°C makes  
the LMP7701/LMP7702/LMP7704 excellent choices for low voltage precision applications with extensive  
temperature requirements.  
The LMP7701/LMP7702/LMP7704 have only ±37 μV of typical input referred offset voltage and this offset is  
specified to be less than ±500 μV for the single and ±520 μV for the dual and quad, over temperature. This  
minimal offset voltage allows more accurate signal detection and amplification in precision applications.  
The low input bias current of only ±200 fA along with the low input referred voltage noise of 9 nV/Hz gives the  
LMP7701/LMP7702/LMP7704 superiority for use in sensor applications. Lower levels of noise from the  
LMP7701/LMP7702/LMP7704 mean of better signal fidelity and a higher signal-to-noise ratio.  
Texas Instruments is heavily committed to precision amplifiers and the market segment they serve. Technical  
support and extensive characterization data is available for sensitive applications or applications with a  
constrained error budget.  
The LMP7701 is offered in the space saving 5-Pin SOT-23 and 8-Pin SOIC package. The LMP7702 comes in  
the 8-Pin SOIC and 8-Pin VSSOP package. The LMP7704 is offered in the 14-Pin SOIC and 14-Pin TSSOP  
package. These small packages are ideal solutions for area constrained PC boards and portable electronics.  
CAPACITIVE LOAD  
The LMP7701/LMP7702/LMP7704 can each be connected as a non-inverting unity gain follower. This  
configuration is the most sensitive to capacitive loading.  
The combination of a capacitive load placed on the output of an amplifier along with the amplifier's output  
impedance creates a phase lag which in turn reduces the phase margin of the amplifier. If the phase margin is  
significantly reduced, the response will be either underdamped or it will oscillate.  
In order to drive heavier capacitive loads, an isolation resistor, RISO, in Figure 45 should be used. By using this  
isolation resistor, the capacitive load is isolated from the amplifier's output, and hence, the pole caused by CL is  
no longer in the feedback loop. The larger the value of RISO, the more stable the output voltage will be. If values  
of RISO are sufficiently large, the feedback loop will be stable, independent of the value of CL. However, larger  
values of RISO result in reduced output swing and reduced output current drive.  
Figure 45. Isolating Capacitive Load  
INPUT CAPACITANCE  
CMOS input stages inherently have low input bias current and higher input referred voltage noise. The  
LMP7701/LMP7702/LMP7704 enhance this performance by having the low input bias current of only ±200 fA, as  
well as, a very low input referred voltage noise of 9 nV/Hz. In order to achieve this a larger input stage has been  
used. This larger input stage increases the input capacitance of the LMP7701/LMP7702/ LMP7704. The typical  
value of this input capacitance, CIN, for the LMP7701/LMP7702/LMP7704 is 25 pF. The input capacitance will  
interact with other impedances such as gain and feedback resistors, which are seen on the inputs of the  
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amplifier, to form a pole. This pole will have little or no effect on the output of the amplifier at low frequencies and  
DC conditions, but will play a bigger role as the frequency increases. At higher frequencies, the presence of this  
pole will decrease phase margin and will also cause gain peaking. In order to compensate for the input  
capacitance, care must be taken in choosing the feedback resistors. In addition to being selective in picking  
values for the feedback resistor, a capacitor can be added to the feedback path to increase stability.  
The DC gain of the circuit shown in Figure 46 is simply –R2/R1.  
C
F
R
2
R
1
-
+
C
IN  
V
+
-
IN  
+
V
OUT  
-
R2  
R1  
VOUT  
VIN  
-
AV =  
-
=
Figure 46. Compensating for Input Capacitance  
For the time being, ignore CF. The AC gain of the circuit in Figure 46 can be calculated as follows:  
VOUT  
VIN  
-R2/R1  
(s) =  
s2  
s
«
«
1 +  
+
A0 R1  
A0  
«
«
R1 + R2  
CIN R2  
This equation is rearranged to find the location of the two poles:  
2
«
4 A0CIN  
R2  
1
1
-1  
1
1
-
P1,2  
=
+
ê
+
«
R1  
R2  
R
R2  
2CIN  
1
(1)  
As shown in Equation 1, as values of R1 and R2 are increased, the magnitude of the poles is reduced, which in  
turn decreases the bandwidth of the amplifier. Whenever possible, it is best to choose smaller feedback resistors.  
Figure 47 shows the effect of the feedback resistor on the bandwidth of the LMP7701/LMP7702/LMP7704.  
2
V
= 5V  
= 0 pF  
= -1  
S
C
F
V
0
-2  
A
R
1
= R = 100 kW  
2
-4  
R
1
= R = 30 kW  
2
-6  
R
1
= R = 10 kW  
2
-8  
R
1
= R = 1 kW  
2
-10  
1k  
10k  
100k  
1M  
10M  
FREQUENCY (Hz)  
Figure 47. Closed Loop Gain vs. Frequency  
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Equation 1 has two poles. In most cases, it is the presence of pairs of poles that causes gain peaking. In order to  
eliminate this effect, the poles should be placed in Butterworth position, since poles in Butterworth position do not  
cause gain peaking. To achieve a Butterworth pair, the quantity under the square root in Equation 1 should be  
set to equal 1. Using this fact and the relation between R1 and R2, R2 = AV R1, the optimum value for R1 can  
be found. This is shown in Equation 2. If R1 is chosen to be larger than this optimum value, gain peaking will  
occur.  
(1 - AV)2  
R1  
<
2A0AVCIN  
(2)  
In Figure 46, CF is added to compensate for input capacitance and to increase stability. Additionally, CF reduces  
or eliminates the gain peaking that can be caused by having a larger feedback resistor. Figure 48 shows how CF  
reduces gain peaking.  
2
C
= 0 pF  
= 1 pF  
F
0
-2  
C
F
C
F
= 5 pF  
-4  
C
= 3 pF  
F
-6  
V
= 5V  
S
-8  
R
1
= R = 100 kW  
2
A
= -1  
V
-10  
1k  
10k  
100k  
1M  
10M  
FREQUENCY (Hz)  
Figure 48. Closed Loop Gain vs. Frequency with Compensation  
DIODES BETWEEN THE INPUTS  
The LMP7701/LMP7702/LMP7704 have a set of anti-parallel diodes between the input pins, as shown in  
Figure 49. These diodes are present to protect the input stage of the amplifier. At the same time, they limit the  
amount of differential input voltage that is allowed on the input pins. A differential signal larger than one diode  
voltage drop might damage the diodes. The differential signal between the inputs needs to be limited to ±300 mV  
or the input current needs to be limited to ±10 mA.  
+
+
V
V
D
1
ESD  
IN  
ESD  
ESD  
R
1
R
2
-
+
IN  
ESD  
D
2
-
-
V
V
Figure 49. Input of LMP7701  
18  
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PRECISION CURRENT SOURCE  
The LMP7701/LMP7702/LMP7704 can each be used as a precision current source in many different  
applications. Figure 50 shows a typical precision current source. This circuit implements a precision voltage  
controlled current source. Amplifier A1 is a differential amplifier that uses the voltage drop across RS as the  
feedback signal. Amplifier A2 is a buffer that eliminates the error current from the load side of the RS resistor that  
would flow in the feedback resistor if it were connected to the load side of the RS resistor. In general, the circuit is  
stable as long as the closed loop bandwidth of amplifier A2 is greater then the closed loop bandwidth of amplifier  
A1. Note that if A1 and A2 are the same type of amplifiers, then the feedback around A1 will reduce its  
bandwidth compared to A2.  
R
R
V
1
+
V
-
R
S
I = (V2 œ V1)  
A
1
RS  
+
-
V
+
V
Z
LOAD  
-
R
R
V
2
A
2
+
-
V
Figure 50. Precision Current Source  
The equation for output current can be derived as follows:  
(V0 œ IRS)R  
V2R  
V1R  
V0R  
=
+
+
R + R  
R + R  
R + R R + R  
Solving for the current I results in the following equation:  
V2 œ V1  
I =  
R
S
LOW INPUT VOLTAGE NOISE  
The LMP7701/LMP7702/LMP7704 have the very low input voltage noise of 9 nV/Hz. This input voltage noise  
can be further reduced by placing N amplifiers in parallel as shown in Figure 51. The total voltage noise on the  
output of this circuit is divided by the square root of the number of amplifiers used in this parallel combination.  
This is because each individual amplifier acts as an independent noise source, and the average noise of  
independent sources is the quadrature sum of the independent sources divided by the number of sources. For N  
identical amplifiers, this means:  
1
2
2
nN  
e2 +e  
n1 n2+....+e  
REDUCED INPUT VOLTAGE NOISE =  
N
N
1
Ne2  
=
=
=
e
n
n
N
N
1
e
n
N
Figure 51 shows a schematic of this input voltage noise reduction circuit. Typical resistor values are:  
RG = 10, RF = 1 k, and RO = 1 k.  
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+
-
V
V
+
-
IN  
V
OUT  
R
O
O
O
R
G
V
R
F
+
V
+
-
R
-
R
G
V
R
F
+
V
+
-
R
-
R
G
V
R
F
+
V
+
-
R
O
-
R
G
V
R
F
Figure 51. Noise Reduction Circuit  
TOTAL NOISE CONTRIBUTION  
The LMP7701/LMP7702/LMP7704 have very low input bias current, very low input current noise, and very low  
input voltage noise. As a result, these amplifiers are ideal choices for circuits with high impedance sensor  
applications.  
Figure 52 shows the typical input noise of the LMP7701/LMP7702/LMP7704 as a function of source resistance  
where:  
en denotes the input referred voltage noise  
ei is the voltage drop across source resistance due to input referred current noise or ei = RS * in  
et shows the thermal noise of the source resistance  
eni shows the total noise on the input.  
Where:  
eni  
=
en2+ e2i + et2  
The input current noise of the LMP7701/LMP7702/LMP7704 is so low that it will not become the dominant factor  
in the total noise unless source resistance exceeds 300 M, which is an unrealistically high value.  
As is evident in Figure 52, at lower RS values, total noise is dominated by the amplifier's input voltage noise.  
Once RS is larger than a few kilo-Ohms, then the dominant noise factor becomes the thermal noise of RS. As  
mentioned before, the current noise will not be the dominant noise factor for any practical application.  
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SNOSAI9H SEPTEMBER 2005REVISED MARCH 2013  
1000  
100  
10  
e
ni  
e
n
e
t
e
i
1
0.1  
10k  
(W)  
1M  
10  
1k  
100k  
10M  
100  
R
S
Figure 52. Total Input Noise  
HIGH IMPEDANCE SENSOR INTERFACE  
Many sensors have high source impedances that may range up to 10 M. The output signal of sensors often  
needs to be amplified or otherwise conditioned by means of an amplifier. The input bias current of this amplifier  
can load the sensor's output and cause a voltage drop across the source resistance as shown in Figure 53,  
where VIN+ = VS – IBIAS*RS  
The last term, IBIAS*RS, shows the voltage drop across RS. To prevent errors introduced to the system due to this  
voltage, an op amp with very low input bias current must be used with high impedance sensors. This is to keep  
the error contribution by IBIAS*RS less than the input voltage noise of the amplifier, so that it will not become the  
dominant noise factor.  
SENSOR  
+
V
I
R
S
B
V
+
IN  
+
-
+
-
V
S
-
V
Figure 53. Noise Due to IBIAS  
pH electrodes are very high impedance sensors. As their name indicates, they are used to measure the pH of a  
solution. They usually do this by generating an output voltage which is proportional to the pH of the solution. pH  
electrodes are calibrated so that they have zero output for a neutral solution, pH = 7, and positive and negative  
voltages for acidic or alkaline solutions. This means that the output of a pH electrode is bipolar and has to be  
level shifted to be used in a single supply system. The rate of change of this voltage is usually shown in mV/pH  
and is different for different pH sensors. Temperature is also an important factor in a pH electrode reading. The  
output voltage of the senor will change with temperature.  
Figure 54 shows a typical output voltage spectrum of a pH electrode. Note that the exact values of output voltage  
will be different for different sensors. In this example, the pH electrode has an output voltage of 59.15 mV/pH at  
25°C.  
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ACID  
BASE  
10  
12  
4
7
14 pH  
0
2
0 mV  
-414 mV  
+414 mV  
+177 mV  
-177 mV  
Figure 54. Output Voltage of a pH Electrode  
The temperature dependence of a typical pH electrode is shown in Figure 55. As is evident, the output voltage  
changes with changes in temperature.  
mV  
600  
10°C (74.04 mV/pH)  
500  
400  
25°C (59.15 mV/pH)  
300  
200  
100  
12  
2
10  
14  
4
8
pH  
0
3
5
7
9
11  
1
13  
-100  
-200  
-300  
-400  
-500  
0°C (54.20 mV/pH)  
-600  
Figure 55. Temperature Dependence of a pH Electrode  
The schematic shown in Figure 56 is a typical circuit which can be used for pH measurement. The LM35 is a  
precision integrated circuit temperature sensor. This sensor is differentiated from similar products because it has  
an output voltage linearly proportional to Celcius measurement, without the need to convert the temperature to  
Kelvin. The LM35 is used to measure the temperature of the solution and feeds this reading to the Analog to  
Digital Converter, ADC. This information is used by the ADC to calculate the temperature effects on the pH  
readings. The LM35 needs to have a resistor, RT in Figure 56, to –V+ in order to be able to read temperatures  
below 0°C. RT is not needed if temperatures are not expected to go below zero.  
The output of pH electrodes is usually large enough that it does not require much amplification; however, due to  
the very high impedance, the output of a pH electrode needs to be buffered before it can go to an ADC. Since  
most ADCs are operated on single supply, the output of the pH electrode also needs to be level shifted. Amplifier  
A1 buffers the output of the pH electrode with a moderate gain of +2, while A2 provides the level shifting. VOUT at  
the output of A2 is given by: VOUT = 2VpH + 1.024V.  
The LM4140A is a precision, low noise, voltage reference used to provide the level shift needed. The ADC used  
in this application is the ADC12032 which is a 12-bit, 2 channel converter with multiplexers on the inputs and a  
serial output. The 12-bit ADC enables users to measure pH with an accuracy of 0.003 of a pH unit. Adequate  
power supply bypassing and grounding is extremely important for ADCs. Recommended bypass capacitors are  
shown in Figure 56. It is common to share power supplies between different components in a circuit. To minimize  
the effects of power supply ripples caused by other components, the op amps need to have bypass capacitors  
on the supply pins. Using the same value capacitors as those used with the ADC are ideal. The combination of  
these three values of capacitors ensures that AC noise present on the power supply line is grounded and does  
not interfere with the amplifiers' signal.  
22  
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SNOSAI9H SEPTEMBER 2005REVISED MARCH 2013  
+
V
pH ELECTRODE TEMPERATURE  
0.01 mF  
0.1 mF  
10 mF  
0.01 mF  
0.1 mF  
10 mF  
+
75W  
1 mF  
V
R
10 kW  
R
2
10 kW  
1
+
-
1
A1  
-
V+  
+
D
+
V
V
V
A
+
V
CH0  
CH1  
R
10 kW  
R
4
10 kW  
-
3
V
OUT  
A2  
+
R
T
+
V
ADC12034  
-
V
V
= 0.5012V  
OFFSET  
LM35  
-V+  
R
5
R
6
3
2
10 kW  
3.3 kW  
6
LM4140A  
1,4,7,8  
AGND  
V
V
-
REF  
+
REF  
DGND  
pH ELECTRODE  
Figure 56. pH Measurement Circuit  
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SNOSAI9H SEPTEMBER 2005REVISED MARCH 2013  
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REVISION HISTORY  
Changes from Revision G (March 2013) to Revision H  
Page  
Changed layout of National Data Sheet to TI format .......................................................................................................... 23  
24  
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PACKAGE OPTION ADDENDUM  
www.ti.com  
1-Nov-2013  
PACKAGING INFORMATION  
Orderable Device  
LMP7701MA/NOPB  
LMP7701MAX/NOPB  
Status Package Type Package Pins Package  
Eco Plan  
Lead/Ball Finish  
MSL Peak Temp  
Op Temp (°C)  
Device Marking  
Samples  
Drawing  
Qty  
(1)  
(2)  
(6)  
(3)  
(4/5)  
ACTIVE  
SOIC  
SOIC  
D
8
8
95  
Green (RoHS  
& no Sb/Br)  
CU SN  
Level-1-260C-UNLIM  
LMP77  
01MA  
ACTIVE  
D
2500  
Green (RoHS  
& no Sb/Br)  
CU SN  
Level-1-260C-UNLIM  
LMP77  
01MA  
LMP7701MF  
NRND  
SOT-23  
SOT-23  
DBV  
DBV  
5
5
1000  
1000  
TBD  
Call TI  
CU SN  
Call TI  
-40 to 125  
-40 to 125  
AC2A  
AC2A  
LMP7701MF/NOPB  
ACTIVE  
Green (RoHS  
& no Sb/Br)  
Level-1-260C-UNLIM  
LMP7701MFX  
NRND  
SOT-23  
SOT-23  
DBV  
DBV  
5
5
3000  
3000  
TBD  
Call TI  
CU SN  
Call TI  
-40 to 125  
-40 to 125  
AC2A  
AC2A  
LMP7701MFX/NOPB  
ACTIVE  
Green (RoHS  
& no Sb/Br)  
Level-1-260C-UNLIM  
LMP7702MA/NOPB  
LMP7702MAX/NOPB  
ACTIVE  
ACTIVE  
SOIC  
SOIC  
D
D
8
8
95  
Green (RoHS  
& no Sb/Br)  
CU SN  
CU SN  
Level-1-260C-UNLIM  
Level-1-260C-UNLIM  
LMP77  
02MA  
2500  
Green (RoHS  
& no Sb/Br)  
LMP77  
02MA  
LMP7702MM  
NRND  
VSSOP  
VSSOP  
DGK  
DGK  
8
8
1000  
1000  
TBD  
Call TI  
CU SN  
Call TI  
-40 to 125  
-40 to 125  
AA3A  
AA3A  
LMP7702MM/NOPB  
ACTIVE  
Green (RoHS  
& no Sb/Br)  
Level-1-260C-UNLIM  
LMP7702MMX/NOPB  
LMP7704MA/NOPB  
LMP7704MAX/NOPB  
LMP7704MT  
ACTIVE  
ACTIVE  
ACTIVE  
NRND  
VSSOP  
SOIC  
DGK  
D
8
3500  
55  
Green (RoHS  
& no Sb/Br)  
CU SN  
CU SN  
CU SN  
Call TI  
CU SN  
CU SN  
Level-1-260C-UNLIM  
Level-1-260C-UNLIM  
Level-1-260C-UNLIM  
Call TI  
-40 to 125  
AA3A  
14  
14  
14  
14  
14  
Green (RoHS  
& no Sb/Br)  
LMP7704  
MA  
SOIC  
D
2500  
94  
Green (RoHS  
& no Sb/Br)  
LMP7704  
MA  
TSSOP  
TSSOP  
TSSOP  
PW  
PW  
PW  
TBD  
-40 to 125  
-40 to 125  
-40 to 125  
LMP77  
04MT  
LMP7704MT/NOPB  
LMP7704MTX/NOPB  
ACTIVE  
ACTIVE  
94  
Pb-Free  
(RoHS)  
Level-1-260C-UNLIM  
Level-1-260C-UNLIM  
LMP77  
04MT  
2500  
Pb-Free  
(RoHS)  
LMP77  
04MT  
(1) The marketing status values are defined as follows:  
ACTIVE: Product device recommended for new designs.  
LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.  
NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design.  
PREVIEW: Device has been announced but is not in production. Samples may or may not be available.  
Addendum-Page 1  
PACKAGE OPTION ADDENDUM  
www.ti.com  
1-Nov-2013  
OBSOLETE: TI has discontinued the production of the device.  
(2) Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS), Pb-Free (RoHS Exempt), or Green (RoHS & no Sb/Br) - please check http://www.ti.com/productcontent for the latest availability  
information and additional product content details.  
TBD: The Pb-Free/Green conversion plan has not been defined.  
Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements for all 6 substances, including the requirement that  
lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes.  
Pb-Free (RoHS Exempt): This component has a RoHS exemption for either 1) lead-based flip-chip solder bumps used between the die and package, or 2) lead-based die adhesive used between  
the die and leadframe. The component is otherwise considered Pb-Free (RoHS compatible) as defined above.  
Green (RoHS & no Sb/Br): TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame retardants (Br or Sb do not exceed 0.1% by weight  
in homogeneous material)  
(3) MSL, Peak Temp. - The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature.  
(4) There may be additional marking, which relates to the logo, the lot trace code information, or the environmental category on the device.  
(5) Multiple Device Markings will be inside parentheses. Only one Device Marking contained in parentheses and separated by a "~" will appear on a device. If a line is indented then it is a continuation  
of the previous line and the two combined represent the entire Device Marking for that device.  
(6) Lead/Ball Finish - Orderable Devices may have multiple material finish options. Finish options are separated by a vertical ruled line. Lead/Ball Finish values may wrap to two lines if the finish  
value exceeds the maximum column width.  
Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information  
provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and  
continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals.  
TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited information may not be available for release.  
In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI to Customer on an annual basis.  
Addendum-Page 2  
PACKAGE MATERIALS INFORMATION  
www.ti.com  
23-Sep-2013  
TAPE AND REEL INFORMATION  
*All dimensions are nominal  
Device  
Package Package Pins  
Type Drawing  
SPQ  
Reel  
Reel  
A0  
B0  
K0  
P1  
W
Pin1  
Diameter Width (mm) (mm) (mm) (mm) (mm) Quadrant  
(mm) W1 (mm)  
LMP7701MAX/NOPB  
LMP7701MF  
SOIC  
SOT-23  
SOT-23  
SOT-23  
SOT-23  
SOIC  
D
8
5
2500  
1000  
1000  
3000  
3000  
2500  
1000  
1000  
3500  
2500  
2500  
330.0  
178.0  
178.0  
178.0  
178.0  
330.0  
178.0  
178.0  
330.0  
330.0  
330.0  
12.4  
8.4  
6.5  
3.2  
3.2  
3.2  
3.2  
6.5  
5.3  
5.3  
5.3  
6.5  
6.95  
5.4  
3.2  
3.2  
3.2  
3.2  
5.4  
3.4  
3.4  
3.4  
9.35  
8.3  
2.0  
1.4  
1.4  
1.4  
1.4  
2.0  
1.4  
1.4  
1.4  
2.3  
1.6  
8.0  
4.0  
4.0  
4.0  
4.0  
8.0  
8.0  
8.0  
8.0  
8.0  
8.0  
12.0  
8.0  
Q1  
Q3  
Q3  
Q3  
Q3  
Q1  
Q1  
Q1  
Q1  
Q1  
Q1  
DBV  
DBV  
DBV  
DBV  
D
LMP7701MF/NOPB  
LMP7701MFX  
5
8.4  
8.0  
5
8.4  
8.0  
LMP7701MFX/NOPB  
LMP7702MAX/NOPB  
LMP7702MM  
5
8.4  
8.0  
8
12.4  
12.4  
12.4  
12.4  
16.4  
12.4  
12.0  
12.0  
12.0  
12.0  
16.0  
12.0  
VSSOP  
VSSOP  
VSSOP  
SOIC  
DGK  
DGK  
DGK  
D
8
LMP7702MM/NOPB  
LMP7702MMX/NOPB  
LMP7704MAX/NOPB  
LMP7704MTX/NOPB  
8
8
14  
14  
TSSOP  
PW  
Pack Materials-Page 1  
PACKAGE MATERIALS INFORMATION  
www.ti.com  
23-Sep-2013  
*All dimensions are nominal  
Device  
Package Type Package Drawing Pins  
SPQ  
Length (mm) Width (mm) Height (mm)  
LMP7701MAX/NOPB  
LMP7701MF  
SOIC  
SOT-23  
SOT-23  
SOT-23  
SOT-23  
SOIC  
D
8
5
2500  
1000  
1000  
3000  
3000  
2500  
1000  
1000  
3500  
2500  
2500  
367.0  
210.0  
210.0  
210.0  
210.0  
367.0  
210.0  
210.0  
367.0  
367.0  
367.0  
367.0  
185.0  
185.0  
185.0  
185.0  
367.0  
185.0  
185.0  
367.0  
367.0  
367.0  
35.0  
35.0  
35.0  
35.0  
35.0  
35.0  
35.0  
35.0  
35.0  
35.0  
35.0  
DBV  
DBV  
DBV  
DBV  
D
LMP7701MF/NOPB  
LMP7701MFX  
5
5
LMP7701MFX/NOPB  
LMP7702MAX/NOPB  
LMP7702MM  
5
8
VSSOP  
VSSOP  
VSSOP  
SOIC  
DGK  
DGK  
DGK  
D
8
LMP7702MM/NOPB  
LMP7702MMX/NOPB  
LMP7704MAX/NOPB  
LMP7704MTX/NOPB  
8
8
14  
14  
TSSOP  
PW  
Pack Materials-Page 2  
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TI warrants performance of its components to the specifications applicable at the time of sale, in accordance with the warranty in TI’s terms  
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