SBOS754A March   2016  – March 2016 TLV2314 , TLV314 , TLV4314

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Device Comparison Table
  6. 6 Pin Configuration and Functions
  7. 7 Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 ESD Ratings
    3. 7.3 Recommended Operating Conditions
    4. 7.4 Thermal Information: TLV314
    5. 7.5 Thermal Information: TLV2314
    6. 7.6 Thermal Information: TLV4314
    7. 7.7 Electrical Characteristics
    8. 7.8 Typical Characteristics
    9. 7.9 Typical Characteristics
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Operating Voltage
      2. 8.3.2 Rail-to-Rail Input
      3. 8.3.3 Rail-to-Rail Output
      4. 8.3.4 Common-Mode Rejection Ratio (CMRR)
      5. 8.3.5 Capacitive Load and Stability
      6. 8.3.6 EMI Susceptibility and Input Filtering
    4. 8.4 Device Functional Modes
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
      3. 9.2.3 Application Curve
    3. 9.3 System Examples
  10. 10Power Supply Recommendations
    1. 10.1 Input and ESD Protection
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Device Support
    2. 12.2 Documentation Support
      1. 12.2.1 Related Documentation
    3. 12.3 Related Links
    4. 12.4 Community Resources
    5. 12.5 Trademarks
    6. 12.6 Electrostatic Discharge Caution
    7. 12.7 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

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

9 Application and Implementation

NOTE

Information in the following applications sections is not part of the TI component specification, and TI does not warrant its accuracy or completeness. TI’s customers are responsible for determining suitability of components for their purposes. Customers should validate and test their design implementation to confirm system functionality.

9.1 Application Information

The TLV314 device is a low-power, rail-to-rail input and output operational amplifier specifically designed for portable applications. These devices operate from 1.8 V to 5.5 V, are unity-gain stable, and suitable for a wide range of general-purpose applications. The class AB output stage is capable of driving ≤ 10-kΩ loads connected to any point between V+ and ground. The input common-mode voltage range includes both rails, and allows the TLV314 device to be used in virtually any single-supply application. Rail-to-rail input and output swing significantly increases dynamic range, especially in low-supply applications, and makes the device ideal for driving sampling analog-to-digital converters (ADCs).

The TLV314 family of devices features a 3-MHz bandwidth and 1.5-V/μs slew rate with only 150-μA supply current per channel, providing good ac performance at very low power consumption. DC applications are also well served with a very-low input noise voltage of 14 nV/√Hz at 1 kHz, low-input bias current (0.2 pA), and an input offset voltage of 0.5 mV (typical).

9.2 Typical Application

A typical application for an operational amplifier is an inverting amplifier, as shown in Figure 15. An inverting amplifier takes a positive voltage on the input and outputs a signal inverted to the input, making a negative voltage of the same magnitude. In the same manner, the amplifier also makes negative input voltages positive on the output. In addition, amplification can be added by selecting the input resistor RI and the feedback resistor RF.

TLV314 TLV2314 TLV4314 app_sch_sbos754.gif Figure 15. Application Schematic

9.2.1 Design Requirements

The supply voltage must be chosen to be larger than the input voltage range and the desired output range. The limits of the input common-mode range (VCM) and the output voltage swing to the rails (VO) must also be considered. For instance, this application scales a signal of ±0.5 V (1 V) to ±1.8 V (3.6 V). Setting the supply at ±2.5 V is sufficient to accommodate this application.

9.2.2 Detailed Design Procedure

Determine the gain required by the inverting amplifier using Equation 1 and Equation 2:

Equation 1. TLV314 TLV2314 TLV4314 app_eq1_sbos754.gif
Equation 2. TLV314 TLV2314 TLV4314 app_eq2_sbos754.gif

When the desired gain is determined, choose a value for RI or RF. Choosing a value in the kilo ohm range is desirable for general-purpose applications because the amplifier circuit uses currents in the milliamp range. This milliamp current range ensures the device does not draw too much current. The trade-off is that very large resistors (100s of kilo ohms) draw the smallest current but generate the highest noise. Very small resistors (100s of ohms) generate low noise but draw high current. This example uses 10 kΩ for RI, meaning 36 kΩ is used for RF. These values are determined by Equation 3:

Equation 3. TLV314 TLV2314 TLV4314 app_eq3_sbos754.gif

9.2.3 Application Curve

TLV314 TLV2314 TLV4314 D125_SBOS754.gif Figure 16. Inverting Amplifier Input and Output

9.3 System Examples

When receiving low-level signals, limiting the bandwidth of the incoming signals into the system is often required. The simplest way to establish this limited bandwidth is to place an RC filter at the noninverting terminal of the amplifier, as Figure 17 shows.

TLV314 TLV2314 TLV4314 ai_single_pole_lpf_bos563.gif Figure 17. Single-Pole, Low-Pass Filter

If even more attenuation is needed, a multiple pole filter is required. The Sallen-Key filter can be used for this task, as Figure 18 shows. For best results, the amplifier must have a bandwidth that is eight to ten times the filter frequency bandwidth. Failure to follow this guideline can result in phase shift of the amplifier.

TLV314 TLV2314 TLV4314 ai_2_pole_sallen_key_lpf_bos563.gif Figure 18. Two-Pole, Low-Pass, Sallen-Key Filter