SLVSAA6B April   2010  – November 2014 TPS54240

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
  6. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 Handling Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics
    6. 6.6 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  Fixed Frequency PWM Control
      2. 7.3.2  Slope Compensation Output Current
      3. 7.3.3  Pulse Skip Eco-Mode
      4. 7.3.4  Low Dropout Operation and Bootstrap Voltage (BOOT)
      5. 7.3.5  Error Amplifier
      6. 7.3.6  Voltage Reference
      7. 7.3.7  Adjusting The Output Voltage
      8. 7.3.8  Enable And Adjusting Undervoltage Lockout
      9. 7.3.9  Slow-Start / Tracking Pin (SS/TR)
      10. 7.3.10 Overload Recovery Circuit
      11. 7.3.11 Sequencing
      12. 7.3.12 Constant Switching Frequency and Timing Resistor (RT/CLK Pin)
      13. 7.3.13 Overcurrent Protection and Frequency Shift
      14. 7.3.14 Selecting the Switching Frequency
      15. 7.3.15 How to Interface to RT/CLK Pin
      16. 7.3.16 Powergood (PWRGD Pin)
      17. 7.3.17 Overvoltage Transient Protection
      18. 7.3.18 Thermal Shutdown
      19. 7.3.19 Small Signal Model for Loop Response
      20. 7.3.20 Simple Small Signal Model for Peak Current Mode Control
      21. 7.3.21 Small Signal Model for Frequency Compensation
    4. 7.4 Device Functional Modes
      1. 7.4.1 Operation Near Minimum VIN (V(VIN) = < 3.5 V)
      2. 7.4.2 Operation With EN Control
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 TPS54240 3.3-V Output Design
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
          1. 8.2.1.2.1  Selecting the Switching Frequency
          2. 8.2.1.2.2  Output Inductor Selection (LO)
          3. 8.2.1.2.3  Output Capacitor
          4. 8.2.1.2.4  Catch Diode
          5. 8.2.1.2.5  Input Capacitor
          6. 8.2.1.2.6  Slow-Start Capacitor
          7. 8.2.1.2.7  Bootstrap Capacitor Selection
          8. 8.2.1.2.8  Undervoltage Lock Out Set Point
          9. 8.2.1.2.9  Output Voltage And Feedback Resistors Selection
          10. 8.2.1.2.10 Compensation
          11. 8.2.1.2.11 Discontinuous Mode And Eco-Mode Boundary
          12. 8.2.1.2.12 Power Dissipation Estimate
        3. 8.2.1.3 Application Curves
      2. 8.2.2 TPS54240 Inverting Power Supply
      3. 8.2.3 TPS54240 Split Rail Power Supply
      4. 8.2.4 12-V To 3.8-V GSM Power Supply
      5. 8.2.5 24-V to 4.2-V GSM Power Supply
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
    3. 10.3 Estimated Circuit Area
  11. 11Device and Documentation Support
    1. 11.1 Device Support
      1. 11.1.1 Third-Party Products Disclaimer
    2. 11.2 Documentation Support
      1. 11.2.1 Related Documentation
    3. 11.3 Trademarks
    4. 11.4 Electrostatic Discharge Caution
    5. 11.5 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

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

5 Pin Configuration and Functions

po_DGQ_DRC_lvsaa6.gif

Pin Functions

PIN I/O DESCRIPTION
NAME NO.
BOOT 1 O A bootstrap capacitor is required between BOOT and PH. If the voltage on this capacitor is below the minimum required by the output device, the output is forced to switch off until the capacitor is refreshed.
COMP 8 O Error amplifier output, and input to the output switch current comparator. Connect frequency compensation components to this pin.
EN 3 I Enable pin, internal pullup current source. Pull below 1.2 V to disable. Float to enable. Adjust the input undervoltage lockout with two resistors.
GND 9 – Ground
PH 10 I The source of the internal high-side power MOSFET.
POWERPAD 11 – GND pin must be electrically connected to the exposed pad on the printed circuit board for proper operation.
PWRGD 6 O An open-drain output, asserts low if output voltage is low due to thermal shutdown, dropout, overvoltage or EN shut down.
RT/CLK 5 I Resistor Timing and External Clock. An internal amplifier holds this pin at a fixed voltage when using an external resistor to ground to set the switching frequency. If the pin is pulled above the PLL upper threshold, a mode change occurs and the pin becomes a synchronization input. The internal amplifier is disabled and the pin is a high impedance clock input to the internal PLL. If clocking edges stop, the internal amplifier is re-enabled and the mode returns to a resistor set function.
SS/TR 4 I Slow-Start and Tracking. An external capacitor connected to this pin sets the output rise time. Since the voltage on this pin overrides the internal reference, it can be used for tracking and sequencing.
VIN 2 I Input supply voltage, 3.5 V to 42 V.
VSENSE 7 I Inverting node of the transconductance (gm) error amplifier.