SNOS990H April   2002  – June 2016 LMV341-N , LMV342-N , LMV344-N


  1. Features
  2. Applications
  3. Description
  4. Revision History
  5. Pin Configuration and Functions
  6. Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics - 2.7 V (DC)
    6. 6.6 Electrical Characteristics - 2.7 V (AC)
    7. 6.7 Electrical Characteristics - 5 V (DC)
    8. 6.8 Electrical Characteristics - 5 V (AC)
    9. 6.9 Typical Characteristics
  7. Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Class AB Turnaround Stage Amplifier
    4. 7.4 Device Functional Modes
      1. 7.4.1 Shutdown Feature
      2. 7.4.2 Low Input Bias Current
  8. Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Sample and Hold Circuit
        1. Design Requirements
        2. Detailed Design Procedure
        3. Application Curve
  9. Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Device Support
      1. 11.1.1 Development Support
    2. 11.2 Documentation Support
      1. 11.2.1 Related Documentation
    3. 11.3 Related Links
    4. 11.4 Receiving Notification of Documentation Updates
    5. 11.5 Community Resources
    6. 11.6 Trademarks
    7. 11.7 Electrostatic Discharge Caution
    8. 11.8 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

7 Detailed Description

7.1 Overview

TI’s LMV34x-N family of amplifiers have 1-MHz bandwidth, 1-V/µs slew rate, a rail-to-rail output stage, and consume only 100 µA of current per amplifier while active. When in shutdown mode it only consumes 45-pA supply consumption with only 20 fA of input bias current. Lastly, these operational amplifiers provide an input-referred voltage noise 29 nV√Hz (at 10 kHz).

7.2 Functional Block Diagram

LMV341-N LMV342-N LMV344-N 20030453.gif

7.3 Feature Description

7.3.1 Class AB Turnaround Stage Amplifier

This patented folded cascode stage has a combined class AB amplifier stage, which replaces the conventional folded cascode stage. Therefore, the class AB folded cascode stage runs at a much lower quiescent current compared to conventional-folded cascode stages. This results in significantly smaller offset and noise contributions. The reduced offset and noise contributions in turn reduce the offset voltage level and the voltage noise level at the input of LMV34x-N. Also the lower quiescent current results in a high open-loop gain for the amplifier. The lower quiescent current does not affect the slew rate of the amplifier nor its ability to handle the total current swing coming from the input stage.

The input voltage noise of the device at low frequencies, below 1 kHz, is slightly higher than devices with a BJT input stage; however, the PMOS input stage results in a much lower input bias current and the input voltage noise drops at frequencies above 1 kHz.

7.4 Device Functional Modes

7.4.1 Shutdown Feature

The LMV341-N is capable of being turned off to conserve power and increase battery life in portable devices. Once in shutdown mode the supply current is drastically reduced, 1-µA maximum, and the output is tri-stated.

The device is disabled when the shutdown pin voltage is pulled low. The shutdown pin must never be left unconnected. Leaving the pin floating results in an undefined operation mode and the device may oscillate between shutdown and active modes.

The LMV341-N typically turns on 2.8 µs after the shutdown voltage is pulled high. The device turns off in less than 400 ns after shutdown voltage is pulled low. Figure 41 and Figure 42 show the turnon and turnoff time of the LMV341-N, respectively. To reduce the effect of the capacitance added to the circuit by the scope probe, in the turnoff time circuit a resistive load of 600 Ω is added. Figure 43 and Figure 44 show the test circuits used to obtain the two plots.

LMV341-N LMV342-N LMV344-N 20030440.gif Figure 41. Turnon Time Plot
LMV341-N LMV342-N LMV344-N 20030442.gif Figure 43. Turnon Time Circuit
LMV341-N LMV342-N LMV344-N 20030439.gif Figure 42. Turnoff Time Plot
LMV341-N LMV342-N LMV344-N 20030443.gif Figure 44. Turnoff Time Circuit

7.4.2 Low Input Bias Current

LMV34x-N amplifiers have a PMOS input stage. As a result, they have a much lower input bias current than devices with BJT input stages. This feature makes these devices ideal for sensor circuits. A typical curve of the input bias current of the LMV341-N is shown in Figure 45.

LMV341-N LMV342-N LMV344-N 20030447.gif Figure 45. Input Bias Current vs VCM