JAJSGX9B August   2018  – January 2020 TLV1805-Q1

PRODUCTION DATA.  

  1. 1 特長
  2. 2 アプリケーション
  3. 3 概要
    1.     Device Images
      1.      N チャネル MOSFET による逆電流保護
      2.      P チャネル MOSFET による逆電流および過電圧保護
  4. 4 改訂履歴
  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. 11デバイスおよびドキュメントのサポート
    1. 11.1 ドキュメントのサポート
      1. 11.1.1 関連資料
    2. 11.2 ドキュメントの更新通知を受け取る方法
    3. 11.3 サポート・リソース
    4. 11.4 商標
    5. 11.5 静電気放電に関する注意事項
    6. 11.6 Glossary
  12. 12メカニカル、パッケージ、および注文情報

8.2.4 Reverse Current Protection Using MOSFET and TLV1805-Q1

An N-Channel or P-Channel MOSFET may be used to protect against reverse current. Reverse current is defined as current flowing from the load (VLOAD) to the source (VBATT). Both the P-Channel and N-Channel circuits work on the same basic principle, where a comparator monitors the voltage across the MOSFET's Source and Drain terminals (monitoring VDS). The described circuits also protect against reverse voltage.

TLV1805-Q1 Basic_Operation.gifFigure 68. Simplified Operational Theory

When the current is flowing from the battery (VBATT) to the load (VLOAD), the battery voltage will be higher than the load voltage due to voltage drop across the MOSFET caused by the RDS(ON) or the intrinsic body diode forward voltage drop. The comparator will detect this and turn "on" the MOSFET so that the load current is now flowing through the low loss RDS(ON) path.

In a reverse current condition, VLOAD will be higher than VBATT. The comparator will detect this and drive the gate to set VGS = 0 to turn "off" the MOSFET (non-conducting). The body diode is reverse biased and will block current flow.

For a P-Channel MOSFET, the gate must be driven at least 4V or more below the battery voltage to turn "on" the MOSFET.

For a N-Channel MOSFET, the gate must be driven 4V or more above the battery voltage to turn "on" the MOSFET. If a higher voltage is not available in the system, a charge pump is usually required to generate a voltage higher than the battery voltage to provide the necessary positive gate drive voltage.