SLVS349F November   2001  – December 2025 TPS794

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Pin Configuration and Functions
  6. 5 Specifications
    1. 5.1 Absolute Maximum Ratings
    2. 5.2 ESD Ratings
    3. 5.3 Recommended Operating Conditions
    4. 5.4 Thermal Information
    5. 5.5 Electrical Characteristics
  7. 6 Typical Characteristics
  8. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagrams
    3. 7.3 Feature Description
      1. 7.3.1 Undervoltage Lockout (UVLO)
      2. 7.3.2 Shutdown
      3. 7.3.3 Active Discharge (new chip)
      4. 7.3.4 Foldback Current Limit
      5. 7.3.5 Thermal Protection
      6. 7.3.6 Reverse Current
    4. 7.4 Device Functional Modes
      1. 7.4.1 Normal Operation
      2. 7.4.2 Dropout Operation
      3. 7.4.3 Disabled
  9. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 Adjustable Operation
      2. 8.1.2 Exiting Dropout
    2. 8.2 Typical Application
      1. 8.2.1 Detailed Design Procedure
        1. 8.2.1.1 Capacitor Recommendations
        2. 8.2.1.2 Input and Output Capacitor Requirements
        3. 8.2.1.3 Noise Reduction and Feed-Forward Capacitor Requirements
      2. 8.2.2 Application Curves
    3. 8.3 Layout
      1. 8.3.1 Board Layout Recommendation to Improve PSRR and Noise Performance
      2. 8.3.2 Power Dissipation
      3. 8.3.3 Thermal Information
        1. 8.3.3.1 Regulator Mounting
      4. 8.3.4 Layout Example
  10. 9 Device and Documentation Support
    1. 9.1 Device Support
      1. 9.1.1 Device Nomenclature
    2. 9.2 Receiving Notification of Documentation Updates
    3. 9.3 Support Resources
    4. 9.4 Trademarks
    5. 9.5 Electrostatic Discharge Caution
    6. 9.6 Glossary
  11. 10Revision History
  12. 11Mechanical, Packaging, and Orderable Information

封装选项

请参考 PDF 数据表获取器件具体的封装图。

机械数据 (封装 | 引脚)
  • DCQ|6
  • DGN|8
散热焊盘机械数据 (封装 | 引脚)
订购信息

7.3.4 Foldback Current Limit

The legacy chip of TPS794 features internal current limiting and thermal protection. During normal operation, the TPS794 limits output current to 925mA (typ). When current limiting engages, the output voltage scales back linearly until the overcurrent condition ends. While current limiting is designed to prevent gross device failure, care must be taken not to exceed the power dissipation ratings of the package or the absolute maximum voltage ratings of the device.

The device has an internal current limit circuit that protects the regulator during transient high-load current faults or shorting events. The current limit is a hybrid brickwall-foldback scheme. The current limit transitions from a brickwall scheme to a foldback scheme at the foldback voltage (VFOLDBACK). In a high-load current fault with the output voltage above VFOLDBACK, the brickwall scheme limits the output current to the current limit (ICL). When the voltage drops below VFOLDBACK, a foldback current limit activates that scales back the current as the output voltage approaches GND. When the output is shorted, the device supplies a typical current called the short-circuit current limit (ISC). ICL and ISC are listed in the Electrical Characteristics table.

For this device, VFOLDBACK = 0.4 × VOUT(NOM).

The output voltage is not regulated when the device is in current limit. When a current limit event occurs, the device begins to heat up because of the increase in power dissipation. When the device is in brickwall current limit, the pass transistor dissipates power [(VIN – VOUT) × ICL]. When the device output is shorted and the output is below VFOLDBACK, the pass transistor dissipates power [(VIN – VOUT) × ISC]. If thermal shutdown is triggered, the device turns off. After the device cools down, the internal thermal shutdown circuit turns the device back on. If the output current fault condition continues, the device cycles between current limit and thermal shutdown. For more information on current limits, see the Know Your Limits application report.

Figure 7-5 shows a diagram of the foldback current limit.

TPS794 Foldback Current LimitFigure 7-5 Foldback Current Limit