SLVSCE9D June   2014  – October  2017 TPS25942A , TPS25942L , TPS25944A , TPS25944L

UNLESS OTHERWISE NOTED, this document contains PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
  4. 4 Revision History
  5. 5 Device Comparison Table
  6. 6 Pin Configuration and Functions
    1.     Pin Functions
  7. 7 Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 ESD Ratings
    3. 7.3 Recommended Operating Conditions
    4. 7.4 Thermal Information
    5. 7.5 Electrical Characteristics
    6. 7.6 Timing Requirements
    7. 7.7 Typical Characteristics
  8. 8 Parameter Measurement Information
  9. 9 Detailed Description
    1. 9.1 Overview
    2. 9.2 Functional Block Diagram
    3. 9.3 Feature Description
      1. 9.3.1  Enable and Adjusting Undervoltage Lockout
      2. 9.3.2  Overvoltage Protection (OVP)
      3. 9.3.3  Hot Plug-In and In-Rush Current Control
      4. 9.3.4  Overload and Short Circuit Protection
        1. 9.3.4.1 Overload Protection
        2. 9.3.4.2 Short Circuit Protection
        3. 9.3.4.3 Start-Up With Short on Output
        4. 9.3.4.4 Constant Current Limit Behavior During Overcurrent Faults
      5. 9.3.5  Reverse Current Protection
      6. 9.3.6  FAULT Response
      7. 9.3.7  Current Monitoring
      8. 9.3.8  Power Good Comparator
      9. 9.3.9  IN, OUT and GND Pins
      10. 9.3.10 Thermal Shutdown
    4. 9.4 Device Functional Modes
      1. 9.4.1 Diode Mode
      2. 9.4.2 Shutdown Control
      3. 9.4.3 Operational Differences Between the TPS25942 and TPS25944
  10. 10Application and Implementation
    1. 10.1 Application Information
    2. 10.2 Typical Application
      1. 10.2.1 Design Requirements
      2. 10.2.2 Detailed Design Procedure
        1. 10.2.2.1 Step by Step Design Procedure
        2. 10.2.2.2 Programming the Current-Limit Threshold: R(ILIM) Selection
        3. 10.2.2.3 Undervoltage Lockout and Overvoltage Set Point
        4. 10.2.2.4 Programming Current Monitoring Resistor—RIMON
        5. 10.2.2.5 Setting Output Voltage Ramp Time (tdVdT)
          1. 10.2.2.5.1 Case1: Start-Up Without Load: Only Output Capacitance C(OUT) Draws Current During Start-Up
          2. 10.2.2.5.2 Case 2: Start-Up With Load: Output Capacitance C(OUT) and Load Draws Current During Start-Up
        6. 10.2.2.6 Programing the Power Good Set Point
        7. 10.2.2.7 Support Component Selections—R6, R7 and CIN
      3. 10.2.3 Application Curves
    3. 10.3 System Examples
      1. 10.3.1 Active ORing (Auto-Power Multiplexer) Operation
        1. 10.3.1.1 N+1 Power Supply Operation
        2. 10.3.1.2 Priority Power MUX Operation
        3. 10.3.1.3 Priority MUXing With Almost Equal Rails (VIN1 ~ VIN2)
        4. 10.3.1.4 Reverse Polarity Protection
  11. 11Power Supply Recommendations
    1. 11.1 Transient Protection
    2. 11.2 Output Short-Circuit Measurements
  12. 12Layout
    1. 12.1 Layout Guidelines
    2. 12.2 Layout Example
  13. 13Device and Documentation Support
    1. 13.1 Device Support
    2. 13.2 Documentation Support
      1. 13.2.1 Related Documentation
    3. 13.3 Related Links
    4. 13.4 Receiving Notification of Documentation Updates
    5. 13.5 Community Resources
    6. 13.6 Trademarks
    7. 13.7 Electrostatic Discharge Caution
    8. 13.8 Glossary
  14. 14Mechanical, Packaging, and Orderable Information

Package Options

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

9.3.1 Enable and Adjusting Undervoltage Lockout

The EN/UVLO pin controls the ON and OFF state of the internal FET. A voltage V(EN/UVLO) < V(ENF) on this pin turns off the internal FET, thus disconnecting IN from OUT, while voltage below 0.6 V takes the device into shutdown mode, with IQ less than 20 µA to ensure minimal power loss. Cycling EN/UVLO low and then back high resets the TPS2594xL that has latched off due to a fault condition.

The internal de-glitch delay on EN/UVLO falling edge is kept low for quick detection of power failure. For applications where a higher de-glitch delay on EN/UVLO is desired, or when the supply is particularly noisy, it is recommended to use an external bypass capacitor from EN/UVLO terminal to GND.

The undervoltage lock out can be programmed by using an external resistor divider from supply IN terminal to EN/UVLO terminal to GND as shown in Figure 50. When an undervoltage or input power fail event is detected, the internal FET is quickly turned off, and FLT is asserted. If the Under-Voltage Lock-Out function is not needed, the EN/UVLO terminal must be connected to the IN terminal. EN/UVLO terminal must not be left floating.

The device also implements internal undervoltage-lockout (UVLO) circuitry on the IN terminal. The device disables when the IN terminal voltage falls below internal UVLO Threshold V(UVF). The internal UVLO threshold has a hysteresis of 115 mV.

TPS25942A TPS25942L TPS25944A TPS25944L EN_UVLO_OVP_Diagram_slvsce9.gifFigure 50. UVLO and OVP Thresholds Set By R1, R2 and R3