3 Femtoampere Input Bias Current Precision Amplifier
Product details
Parameters
Package | Pins | Size
Features
- Unless Otherwise Noted, Typical Values at TA =
25°C, VS = 5 V. - Input Bias Current (VCM = 1 V)
- Maximum at 25°C ±20 fA
- Maximum at 85°C ±900 fA
- Offset Voltage ±26 µV
- Offset Voltage Drift – 1.5 µV/°C
- DC Open-Loop Gain 120 dB
- DC CMRR 100 dB
- Input Voltage Noise (at f = 1 kHz) 6.5 nV/√Hz
- THD 0.0007%
- Supply Current 1.3 mA
- GBW 17 MHz
- Slew Rate (Falling Edge) 12.76 V/µs
- Supply Voltage 1.8 V to 5.5 V
- Operating Temperature Range –40°C to 125°C
- 8-Pin SOIC
Description
The LMP7721 is the industry’s lowest specified input bias current precision amplifier. The ultra-low input bias current is 3 fA, with a specified limit of ±20 fA at 25°C and ±900 fA at 85°C. This is achieved with the latest patent-pending technology of input bias current cancellation amplifier circuitry. This technology also maintains the ultra-low input bias current over the entire input common-mode voltage range of the amplifier.
Other outstanding features, such as low voltage noise (6.5 nV/√Hz), low DC-offset voltage (±150 µV maximum at 25°C) and low-offset voltage temperature coefficient (–1.5 µV/°C), improve system sensitivity and accuracy in high-precision applications. With a supply voltage range of 1.8 V to 5.5 V, the LMP7721 is the ideal choice for battery-operated, portable applications. The LMP7721 is part of the LMP precision amplifier family.
As part of Texas Instruments’ PowerWise™ products, the LMP7721 provides the remarkably wide-gain bandwidth product (GBW) of 17 MHz while consuming only 1.3 mA of current. This wide GBW along with the high open-loop gain of 120 dB enables accurate signal conditioning. With these specifications, the LMP7721 has the performance to excel in a wide variety of applications such as electrochemical cell amplifiers and sensor interface circuits.
The LMP7721 is offered in an 8-pin SOIC package with a special pinout that isolates the amplifier’s input from the power supply and output pins. With proper board layout techniques, the unique pinout of the LMP7721 will prevent PCB leakage current from reaching the input pins. Thus system error will be further reduced.
Technical documentation
= Top documentation for this product selected by TI
| Type | Title | Date | |
|---|---|---|---|
| * | Datasheet | LMP7721 3-Femtoampere Input Bias Current Precision Amplifier datasheet (Rev. E) | Dec. 15, 2014 |
| Application note | Low-input bias-current front end SAR ADC circuit (Rev. A) | Mar. 11, 2019 | |
| Application note | Photodiode amplifier circuit (Rev. A) | Feb. 04, 2019 | |
| E-book | The Signal e-book: A compendium of blog posts on op amp design topics | Mar. 28, 2017 | |
| Technical articles | Minimize your current, pick a sweet spot! | Sep. 03, 2014 | |
| User guide | AN-1796 LMP7721 Evaluation Board (Rev. C) | May 01, 2013 | |
| Application note | AN-1798 Designing with Electro-Chemical Sensors (Rev. C) | May 01, 2013 | |
| Application note | AN-1852 Designing With pH Electrodes (Rev. A) | May 01, 2013 | |
| More literature | Die D/S LMP7721-MDC Femtoampere Input Bias Currect Precision Amplifier | Jan. 08, 2013 | |
| User guide | LMP7721 Multi-Function Evaluation Board | Jan. 26, 2012 |
Design & development
For additional terms or required resources, click any title below to view the detail page where available.Hardware development
DIP-ADAPTER-EVM
Description
Speed up your op amp prototyping and testing with the DIP-Adapter-EVM, which provides a fast, easy and inexpensive way to interface with small, surface-mount ICs. You can connect any supported op amp using the included Samtec terminal strips or wire them directly to existing circuits.
The (...)
Features
- Simplifies prototyping of SMT IC’s
- Supports 6 common package types
- Low Cost
Description
The DIYAMP-EVM is a unique evaluation module (EVM) family that provides engineers and do it yourselfers (DIYers) with real-world amplifier circuits, enabling you to quickly evaluate design concepts and verify simulations. It is available in three industry-standard packages (SC70, SOT23, SOIC) and 12 (...)
Features
- 3 packages to choose from: SC70-5, SOT23-5 and SOIC-8
- 12 circuit configurations to choose from: Noninverting, Inverting, Active Filters, Difference Amp, Comparator and more!
- Dual and single supply configurations
- PCB designed for High performance: Optimized for each function
- Multiple interface options (...)
LMP7721MAEVALMF_NOPB
Design tools & simulation
SNOM304B.ZIP (9 KB) - TINA-TI Spice Model
PSPICE-FOR-TI — PSpice® for TI is a design and simulation environment that helps evaluate functionality of analog circuits. This full-featured, design and simulation suite uses an analog analysis engine from Cadence®. Available at no cost, PSpice for TI includes one of the largest model libraries in the (...)
Features
- Leverages Cadence PSpice Technology
- Preinstalled library with a suite of digital models to enable worst-case timing analysis
- Dynamic updates ensure you have access to most current device models
- Optimized for simulation speed without loss of accuracy
- Supports simultaneous analysis of multiple products
- (...)
TINA-TI — TINA-TI provides all the conventional DC, transient and frequency domain analysis of SPICE and much more. TINA has extensive post-processing capability that allows you to format results the way you want them. Virtual instruments allow you to select input waveforms and probe circuit nodes voltages (...)
ANALOG-ENGINEER-CALC — The Analog Engineer’s Calculator is designed to speed up many of the repetitive calculations that analog circuit design engineers use on a regular basis. This PC-based tool provides a graphical interface with a list of various common calculations ranging from setting op-amp gain with feedback (...)
Features
- Expedites circuit design with analog-to-digital converters (ADCs) and digital-to-analog converters (DACs)
- Noise calculations
- Common unit translation
- Solves common amplifier circuit design problems
- Gain selections using standard resistors
- Filter configurations
- Total noise for common amplifier configurations
- (...)
OPAMP-NOISECALC — This folder contains three tools to help in understandning and managing noise in cicuits. The included tools are:
- A noise generator tool - This is a Lab View 4-Run Time executable that generates Gaussian white noise, uniform white noise, 1/f noise, short noise, and 60Hz line noise. Temporal data (...)
CIRCUIT060001 — This single–supply, low–side, current sensing solution accurately detects load current up to 1A and converts it to a voltage between 50mV and 4.9V. The input current range and output voltage range can be scaled as necessary and larger supplies can be used to accommodate larger swings.
Features
- Senses Temperature between 25°C - 50°C
- Output: 0.05V - 3.25V
- Single 3.3V Supply with half-supply reference
CIRCUIT060002 — This temperature sensing circuit uses a resistor in series with a negative–temperature–coefficient (NTC) thermistor to form a voltage divider, which has the effect of producing an output voltage that is linear over temperature. The circuit uses an op amp in a non–inverting (...)
Features
- Senses Temperature between 25°C - 50°C
- Output: 0.05V - 3.25V
- Single 3.3V Supply with half-supply reference
CIRCUIT060003 — This temperature sensing circuit uses a resistor in series with a positive–temperature–coefficient (PTC) thermistor to form a voltage–divider, which has the effect of producing an output voltage that is linear over temperature. The circuit uses an op amp in a non–inverting (...)
Features
- Senses Temperature between 0°C - 50°C
- Output: 0.05V - 3.25V
- Single 3.3V Supply with half-supply reference
CIRCUIT060004 — This two stage amplifier design amplifies and filters the signal from a passive infrared (PIR) sensor. The circuit includes multiple low–pass and high–pass filters to reduce noise at the output of the circuit to be able to detect motion at long distances and reduce false triggers. This (...)
Features
- Single 5V Supply
- Passes frequencies between 0.7Hz - 10Hz
- AC Gain: 90dB
CIRCUIT060005 — This single–supply, high–side, low–cost current sensing solution detects load current between 50mA and 1A and converters it to an output voltage from 0.25V to 5V. High–side sensing allows for the system to identify ground shorts and does not create a ground disturbance on the load.
Features
- Single 36V supply
- Input: 50mA to 1A
- Output: 0.25V to 5V
CIRCUIT060006 — A strain gauge is a sensor whose resistance varies with applied force. To measure the variation in resistance, the strain gauge is placed in a bridge configuration. This design uses a 2 op amp instrumentation circuit to amplify a differential signal created by the change in resistance of a strain (...)
Features
- Single 5V supply with half-supply reference
- Input: -2.22mV to 2.27mV differential
- Output: 225mV - 4.72V
- Strain gauge resistance variation: 115 - 125 Ohms
- Gain: 1001V/V
CIRCUIT060007 — This single-supply low-side, bidirectional current sensing solution can accurately detect load currents from –1A to 1A. The linear range of the output is from 110mV to 3.19V. Low-side current sensing keeps the common-mode voltage near ground, and is thus most useful in applications with large (...)
Features
- Single 5V supply with half-supply reference
- Input: -2.22mV to 2.27mV differential
- Output: 225mV - 4.72V
- Strain gauge resistance variation: 115 - 125 Ohms
- Gain: 1001V/V
CIRCUIT060008 — This absolute value circuit can turn alternating current (AC) signals to single polarity signals. This circuit functions with limited distortion for ±10-V input signals at frequencies up to 50kHz and for signals as small as ±25mV at frequencies up to 1kHz.
Features
- 30V Split supply with ground reference
- Input: +/-25mV to +/-10V
- Output: 25mV to 10V
CIRCUIT060009 — The precision half-wave rectifier inverts and transfers only the negative-half input of a time varying input signal (preferably sinusoidal) to its output. By appropriately selecting the feedback resistor values, different gains can be achieved. Precision half-wave rectifiers are commonly used with (...)
Features
- 5V Split supply
- Input: +/-0.2mVpp to +/-4Vpp
- Output: 0.1V to 2V
CIRCUIT060010 — This circuit utilizes a triangle wave generator and comparator to generate a 500 kHz pulse-width modulated (PWM) waveform with a duty cycle that is inversely proportional to the input voltage. An op amp and comparator generate a triangle waveform which is applied to the inverting input of a second (...)
Features
- 5V Single supply with half-supply reference
- Input: -2V to 2V
- Output: 0V to 5V
SBOC517.ZIP (258 KB)
CAD/CAE symbols
| Package | Pins | Download |
|---|---|---|
| SOIC (D) | 8 | View options |
Ordering & quality
Information included:
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- REACH
- Device marking
- Lead finish/Ball material
- MSL rating/Peak reflow
- MTBF/FIT estimates
- Material content
- Qualification summary
- Ongoing reliability monitoring
Support & training
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