SNOSD52B August   2018  – January 2020 TLV1805-Q1

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      Reverse Current Protection Using an N-Channel MOSFET
      2.      Reverse Current & Overvoltage Protection Using P-Channel MOSFETs
  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
    6. 6.6 Switching Characteristics
    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 Rail to Rail Inputs
      2. 7.3.2 Power On Reset
      3. 7.3.3 High Power Push-Pull Output
      4. 7.3.4 Shutdown Function
      5. 7.3.5 Internal Hysteresis
    4. 7.4 Device Functional Modes
      1. 7.4.1 External Hysteresis
        1. 7.4.1.1 Inverting Comparator With Hysteresis
        2. 7.4.1.2 Noninverting Comparator With Hysteresis
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Applications
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
      3. 8.2.3 Application Curve
      4. 8.2.4 Reverse Current Protection Using MOSFET and TLV1805-Q1
        1. 8.2.4.1 Minimum Reverse Current
        2. 8.2.4.2 N-Channel Reverse Current Protection Circuit
          1. 8.2.4.2.1 N-Channel Oscillator Circuit
      5. 8.2.5 P-Channel Reverse Current Protection Circuit
      6. 8.2.6 P-Channel Reverse Current Protection With Overvotlage Protection
      7. 8.2.7 ORing MOSFET Controller
  9. 9 Power Supply Recommendations
  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 Support Resources
    4. 11.4 Trademarks
    5. 11.5 Electrostatic Discharge Caution
    6. 11.6 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

8.2.4.1 Minimum Reverse Current

There is a minimum amount of reverse current that is needed to trip the comparator. To detect this reverse current, a voltage must be dropped across the MOSFET (VMEAS).

When the MOSFET is off, VGS will be in the -600mV to -1V range due to the forward voltage drop (VF) of the MOSFET body diode. Response to this large voltage will be immediate.

However, with the MOSFET "on" (conducting), the current required to create the trip voltage will be much greater. The trip voltage drop required across the MOSFET RDS(ON) will be the comparator offset voltage plus half of the hysteresis.

The maximum offset voltage of the TLV1805-Q1 is 5mV with a typical hysteresis of 14mV. The trip voltage can be calculated from:

Equation 7. VTRIP = VOS(max) + ( VHYST / 2) = 5 mV + 7 mV = 12 mV

The actual current trip point will depend on the MOSFET RDS(ON) and VGS drive level. Assuming the MOSFET has a 22 mΩ on resistance, the trip current is found from:

Equation 8. ITRIP = VTRIP / RDS(ON) = 12 mV / 22 mΩ = 546mA