SLOS969A June   2017  – January 2018 LMV722-Q1

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      Simplified Schematic
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
    1.     Pin Functions
  6. 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 VCC+ = 2.2 V
    6. 6.6 Electrical Characteristics VCC+ = 5 V
    7. 6.7 Typical Characteristics
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Low Noise
      2. 7.3.2 Rail-to-Rail Output
      3. 7.3.3 Input Includes Ground
      4. 7.3.4 Signal Integrity
    4. 7.4 Device Functional Modes
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
      3. 8.2.3 Application Curve
  9. 9 Power Supply Recommendations
    1. 9.1 Input and ESD Protection
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Documentation Support
      1. 11.1.1 Related Documentation
    2. 11.2 Receiving Notification of Documentation Updates
    3. 11.3 Community Resources
    4. 11.4 Trademarks
    5. 11.5 Electrostatic Discharge Caution
    6. 11.6 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

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

8.2.2 Detailed Design Procedure

The transfer function of the circuit in Figure 26 is given in Equation 1

Equation 1. LMV722-Q1 EQ_2_SBOS701.gif

The load current (ILOAD) produces a voltage drop across the shunt resistor (RSHUNT). The load current is set from 0 A to 1 A. To keep the shunt voltage below 100 mV at maximum load current, the largest shunt resistor is defined using Equation 2.

Equation 2. LMV722-Q1 EQ_3_SBOS701.gif

Using Equation 2, RSHUNT is calculated to be 100 mΩ. The voltage drop produced by ILOAD and RSHUNT is amplified by the LMV722-Q1 to produce an output voltage of roughly 0 V to 4.9 V. The gain needed by the LMV722-Q1 to produce the necessary output voltage is calculated using Equation 3:

Equation 3. LMV722-Q1 EQ_4_SBOS701.gif

Using Equation 3, the required gain is calculated to be 49 V/V, which is set with resistors RF and RG. Equation 4 is used to size the resistors, RF and RG, to set the gain of the LMV722-Q1 to 49 V/V.

Equation 4. LMV722-Q1 EQ_5_SBOS701.gif

Choosing RF as 57.6 kΩ and RG as 1.2 kΩ provides a combination that equals roughly 49 V/V. Figure 27 shows the measured transfer function of the circuit shown in Figure 26.