SBOS839M March   2017  – December 2024 TLV9061 , TLV9062 , TLV9064

PRODMIX  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5.   Device Comparison Table
  6. 4 Pin Configuration and Functions
  7. 5 Specifications
    1. 5.1  Absolute Maximum Ratings
    2. 5.2  ESD Ratings
    3. 5.3  Recommended Operating Conditions
    4. 5.4  Thermal Information: TLV9061
    5. 5.5  Thermal Information: TLV9061S
    6. 5.6  Thermal Information: TLV9062
    7. 5.7  Thermal Information: TLV9062S
    8. 5.8  Thermal Information: TLV9064
    9. 5.9  Thermal Information: TLV9064S
    10. 5.10 Electrical Characteristics
    11. 5.11 Typical Characteristics
  8. 6 Detailed Description
    1. 6.1 Overview
    2. 6.2 Functional Block Diagram
    3. 6.3 Feature Description
      1. 6.3.1 Rail-to-Rail Input
      2. 6.3.2 Rail-to-Rail Output
      3. 6.3.3 EMI Rejection
      4. 6.3.4 Overload Recovery
      5. 6.3.5 Shutdown Function
    4. 6.4 Device Functional Modes
  9. 7 Application and Implementation
    1. 7.1 Application Information
    2. 7.2 Typical Applications
      1. 7.2.1 Typical Low-Side Current Sense Application
      2. 7.2.2 Design Requirements
      3. 7.2.3 Detailed Design Procedure
      4. 7.2.4 Application Curve
    3. 7.3 Power Supply Recommendations
      1. 7.3.1 Input and ESD Protection
    4. 7.4 Layout
      1. 7.4.1 Layout Guidelines
      2. 7.4.2 Layout Example
  10. 8 Device and Documentation Support
    1. 8.1 Documentation Support
      1. 8.1.1 Related Documentation
    2. 8.2 Receiving Notification of Documentation Updates
    3. 8.3 Support Resources
    4. 8.4 Trademarks
    5. 8.5 Electrostatic Discharge Caution
    6. 8.6 Glossary
  11. 9 Revision History
  12. 10Mechanical, Packaging, and Orderable Information

7.2.3 Detailed Design Procedure

The transfer function of the circuit in Figure 7-1 is given in Equation 1.

Equation 1. V O U T = I L O A D   ×   R S H U N T   ×   G A I N

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

Equation 2. R S H U N T   =   V S H U N T _ M A X   I L O A D _ M A X   =   100 m V 1 A   =   100 m Ω

Using Equation 2, RSHUNT equals 100mΩ. The voltage drop produced by ILOAD and RSHUNT is amplified by the TLV906x to produce an output voltage of approximately 0V to 4.95V. Equation 3 calculates the gain required for the TLV906x to produce the required output voltage.

Equation 3. G a i n   =   ( V O U T _ M A X   –   V O U T _ M I N ) ( V I N _ M A X   –   V I N _ M I N )

Using Equation 3, the required gain equals 49.5V/V, which is set with the RF and RG resistors. Equation 4 sizes the RF and RG, resistors to set the gain of the TLV906x to 49.5V/V.

Equation 4. G a i n   =   1   +   ( R F ) ( R G )

Selecting RF to equal 165kΩ and RG to equal 3.4kΩ provides a combination that equals approximately 49.5V/V. Figure 7-2 shows the measured transfer function of the circuit shown in Figure 7-1. Notice that the gain is only a function of the feedback and gain resistors. This gain is adjusted by varying the ratio of the resistors and the actual resistor values are determined by the impedance levels that the designer wants to establish. The impedance level determines the current drain, the effect that stray capacitance has, and a few other behaviors. There is no optimal impedance selection that works for every system, you must choose an impedance that is ideal for your system parameters.