Overview
The LMP7721MAX/NOPB, produced by Texas Instruments, is a precision amplifier renowned for its ultra-low input bias current. This amplifier is part of the LMP precision amplifier family and is designed to offer exceptional performance in high-precision applications. With an input bias current as low as 3 femtoamperes (fA) and a specified limit of ±20 fA at 25°C and ±900 fA at 85°C, it is the industry’s lowest specified input bias current precision amplifier. This is achieved through Texas Instruments' patent-pending technology of input bias current cancellation amplifier circuitry, which maintains the ultra-low input bias current over the entire input common-mode voltage range of the amplifier.
Key Specifications
| Specification | Value | Unit |
|---|---|---|
| Input Bias Current (VCM = 1 V) | ±20 fA (at 25°C), ±900 fA (at 85°C) | fA |
| Offset Voltage | ±26 µV | µV |
| Offset Voltage Drift | 1.5 µV/°C | µV/°C |
| DC Open-Loop Gain | 120 dB | dB |
| DC CMRR | 100 dB | dB |
| Input Voltage Noise (at f = 1 kHz) | 6.5 nV/√Hz | nV/√Hz |
| THD | 0.0007% | % |
| Supply Current | 1.3 mA | mA |
| GBW | 17 MHz | MHz |
| Slew Rate (Falling Edge) | 12.76 V/µs | V/µs |
| Supply Voltage | 1.8 V to 5.5 V | V |
| Operating Temperature Range | -40°C to 125°C | °C |
| Package | 8-Pin SOIC |
Key Features
- Ultra-Low Input Bias Current: The LMP7721 features an input bias current as low as 3 fA, making it ideal for high-precision applications where minimal input current is crucial.
- Low Voltage Noise: With an input voltage noise of 6.5 nV/√Hz at 1 kHz, this amplifier enhances system sensitivity and accuracy.
- Low Offset Voltage and Drift: The amplifier has a low offset voltage of ±26 µV and a low offset voltage drift of 1.5 µV/°C, ensuring stable performance over temperature variations.
- Wide Gain Bandwidth Product (GBW): The LMP7721 offers a GBW of 17 MHz while consuming only 1.3 mA of current, making it suitable for battery-operated and portable applications.
- Special Pinout: The 8-pin SOIC package has a unique pinout that isolates the amplifier’s input from the power supply and output pins, reducing system error and PCB leakage current.
Applications
- Electrochemical Cell Amplifiers: The ultra-low input bias current and low noise make the LMP7721 ideal for amplifying signals from electrochemical cells.
- High Impedance Sensor Amplifiers: Suitable for amplifying signals from high-impedance sensors due to its low input bias current and high input impedance.
- Ion Chamber Amplifiers: Used in ion chamber applications where low input bias current is essential.
- pH Electrode Amplifiers: Ideal for pH electrode applications requiring high precision and low noise.
- Transimpedance Amplifiers: The LMP7721 can be used in transimpedance amplifier configurations for converting current signals to voltage signals with high accuracy.
Q & A
- What is the input bias current of the LMP7721?
The input bias current of the LMP7721 is as low as 3 fA, with a specified limit of ±20 fA at 25°C and ±900 fA at 85°C.
- What is the offset voltage of the LMP7721?
The offset voltage of the LMP7721 is ±26 µV.
- What is the gain bandwidth product (GBW) of the LMP7721?
The GBW of the LMP7721 is 17 MHz.
- What is the supply voltage range of the LMP7721?
The supply voltage range of the LMP7721 is from 1.8 V to 5.5 V.
- What is the operating temperature range of the LMP7721?
The operating temperature range of the LMP7721 is from -40°C to 125°C.
- What package type is the LMP7721 available in?
The LMP7721 is available in an 8-pin SOIC package.
- What are some typical applications of the LMP7721?
Typical applications include electrochemical cell amplifiers, high impedance sensor amplifiers, ion chamber amplifiers, pH electrode amplifiers, and transimpedance amplifiers.
- How does the unique pinout of the LMP7721 benefit the design?
The unique pinout isolates the amplifier’s input from the power supply and output pins, reducing system error and PCB leakage current.
- What is the slew rate of the LMP7721?
The slew rate of the LMP7721 is 12.76 V/µs (falling edge).
- What is the total harmonic distortion (THD) of the LMP7721?
The THD of the LMP7721 is 0.0007%.
