SLVSGM3B March   2023  – January 2024 TPS56836 , TPS56837 , TPS56838

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
    6. 5.6 Typical Characteristics
  7. 6 Detailed Description
    1. 6.1 Overview
    2. 6.2 Functional Block Diagram
    3. 6.3 Feature Description
      1. 6.3.1  The Adaptive On-Time Control and PWM Operation
      2. 6.3.2  Mode Selection
      3. 6.3.3  Soft Start and Pre-Biased Soft Start
      4. 6.3.4  Enable and Adjusting Undervoltage Lockout
      5. 6.3.5  Output Overcurrent Limit and Undervoltage Protection
      6. 6.3.6  Overvoltage Protection
      7. 6.3.7  UVLO Protection
      8. 6.3.8  Thermal Shutdown
      9. 6.3.9  Output Voltage Discharge
      10. 6.3.10 Power Good
      11. 6.3.11 Large Duty Operation
    4. 6.4 Device Functional Modes
      1. 6.4.1 Standby Operation
      2. 6.4.2 Eco-mode
      3. 6.4.3 Forced Continuous Conduction Mode
      4. 6.4.4 Out-of-Audio™ Mode
  8. 7 Application and Implementation
    1. 7.1 Application Information
    2. 7.2 Typical Application
      1. 7.2.1 Design Requirements
      2. 7.2.2 Detailed Design Procedure
        1. 7.2.2.1 Custom Design With WEBENCH® Tools
        2. 7.2.2.2 Output Voltage Resistors Selection
        3. 7.2.2.3 Output Filter Selection
        4. 7.2.2.4 Input Capacitor Selection
        5. 7.2.2.5 Bootstrap Capacitor Selection
      3. 7.2.3 Application Curves
    3. 7.3 Power Supply Recommendations
    4. 7.4 Layout
      1. 7.4.1 Layout Guidelines
      2. 7.4.2 Layout Example
  9. 8 Device and Documentation Support
    1. 8.1 Device Support
      1. 8.1.1 Development Support
        1. 8.1.1.1 Custom Design With WEBENCH® Tools
    2. 8.2 Documentation Support
      1. 8.2.1 Related Documentation
    3. 8.3 Receiving Notification of Documentation Updates
    4. 8.4 Support Resources
    5. 8.5 Trademarks
    6. 8.6 Electrostatic Discharge Caution
    7. 8.7 Glossary
  10. 9 Revision History
  11. 10Mechanical, Packaging, and Orderable Information

Package Options

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

6.3.4 Enable and Adjusting Undervoltage Lockout

The EN pin provides electrical on and off control of the device. When the EN pin voltage exceeds the threshold voltage, the device begins operating. If the EN pin voltage is pulled below the threshold voltage, the regulator stops switching and enters the standby operation.

The EN pin has an internal pullup current source which allows the user to float the EN pin to enable the device. If an application requires control of the EN pin, open-drain or open-collector output logic can be used to interface with the pin.

The TPS5683x implements internal undervoltage lockout (UVLO) circuitry on the VIN pin. The device is disabled when the VIN pin voltage falls below the internal VIN UVLO threshold. The internal VIN UVLO threshold has a hysteresis of 500mV.

If an application requires a higher UVLO threshold on the VIN pin, then the EN pin can be configured as shown in Figure 6-2. When using the external UVLO function, TI recommends setting the hysteresis at a value greater than 500mV.

The EN pin has a small pullup current, Ip, which sets the default state of the pin to enable when no external components are connected. The pullup current is also used to control the voltage hysteresis for the UVLO function because it increases by Ih when the EN pin crosses the enable threshold. Use Equation 2, and Equation 3 to calculate the values of R1 and R2 for a specified UVLO threshold. After R1, R2 settle down, the VEN voltage can be calculated by Equation 4, which must be lower than 5.5V with maximum VEN.

GUID-20240110-SS0I-CV0D-PQDJ-4ZL9SM62VQG4-low.svgFigure 6-2 Adjustable VIN Undervoltage Lockout
Equation 2. R1=VSTART×VENfallingVENrising-VSTOPIp×1-VENfallingVENrising+Ih
Equation 3. R2=R1×VENfallingVSTOP-VENfalling+R1×Ip+Ih
Equation 4. VEN=R2×VIN+R1×R2×Ip+IhR1+R2

Where

  • Ip = 1µA
  • Ih = 3µA
  • VENfalling = 1.07V
  • VENrising = 1.18V