SLVSCL3E June   2014  – May 2019 TPS65283 , TPS65283-1

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Typical Schematic
    1.     Efficiency, Vin = 12 V, PSM
  5. 5 Revision History
  6. 6 Description (continued)
  7. 7 Pin Configuration and Functions
    1.     Pin Functions
  8. 8 Specifications
    1. 8.1 Absolute Maximum Ratings
    2. 8.2 Handling Ratings
    3. 8.3 Recommended Operating Conditions
    4. 8.4 Thermal Information
    5. 8.5 Electrical Characteristics
    6. 8.6 Typical Characteristics
  9. 9 Detailed Description
    1. 9.1 Overview
    2. 9.2 Functional Block Diagram
    3. 9.3 Feature Description
      1. 9.3.1 Power Switch Detailed Description
        1. 9.3.1.1 Overcurrent Condition
        2. 9.3.1.2 Reverse Current and Voltage Protection
        3. 9.3.1.3 nFAULT Response
        4. 9.3.1.4 UVLO
        5. 9.3.1.5 Enable and Output Discharge
        6. 9.3.1.6 Power Switch Input and Output Capacitance
        7. 9.3.1.7 Programming the Current-Limit Threshold
      2. 9.3.2 Buck DC-DC Converter Detailed Description
        1. 9.3.2.1  Output Voltage
        2. 9.3.2.2  Adjustable Switching Frequency
        3. 9.3.2.3  Synchronization
        4. 9.3.2.4  Error Amplifier
        5. 9.3.2.5  Slope Compensation
        6. 9.3.2.6  Enable and Adjusting UVLO
        7. 9.3.2.7  Internal V7V Regulator
        8. 9.3.2.8  Short Circuit Protection
          1. 9.3.2.8.1 High-Side MOSFET Overcurrent Protection
          2. 9.3.2.8.2 Low-Side MOSFET Overcurrent Protection
        9. 9.3.2.9  Bootstrap Voltage (BST) and Low Dropout Operation
        10. 9.3.2.10 Output Overvoltage Protection (OVP)
        11. 9.3.2.11 Power Good
        12. 9.3.2.12 Power-Up Sequencing
        13. 9.3.2.13 Thermal Performance
    4. 9.4 Device Functional Modes
      1. 9.4.1 Operation With VIN < 4.5 V (Minimum VIN)
      2. 9.4.2 Operation With EN Control
      3. 9.4.3 Operation at Light Loads
  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 Output Voltage Setting
        2. 10.2.2.2 Bootstrap Capacitor Selection
        3. 10.2.2.3 Inductor Selection
        4. 10.2.2.4 Output Capacitor Selection
        5. 10.2.2.5 Input Capacitor Selection
        6. 10.2.2.6 Minimum Output Voltage
        7. 10.2.2.7 Compensation Component Selection
      3. 10.2.3 Application Curves
  11. 11Power Supply Recommendations
  12. 12Layout
    1. 12.1 Layout Guidelines
      1. 12.1.1 PCB Layout Recommendation
      2. 12.1.2 Power Dissipation and Junction Temperature
    2. 12.2 Layout Example
  13. 13Device and Documentation Support
    1. 13.1 Documentation Support
      1. 13.1.1 Related Links
    2. 13.2 Trademarks
    3. 13.3 Electrostatic Discharge Caution
    4. 13.4 Glossary
  14. 14Mechanical, Packaging, and Orderable Information

Package Options

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

10.2.2.7 Compensation Component Selection

Integrated buck converters in TPS65283, TPS65283-1 incorporate a peak current mode. The error amplifier is a transconductance amplifier with a gain of 300 µA/V. A typical type II compensation circuit adequately delivers a phase margin between 60° and 90°. Cb adds a high-frequency pole to attenuate high-frequency noise when needed. To calculate the external compensation components, follow these steps.

  1. Select switching frequency ƒSW that is appropriate for application depending on L and C sizes, output ripple, EMI, and so forth. Switching frequency between 500 kHz to 1 MHz gives the best trade-off between performance and cost. To optimize efficiency, lower switching frequency is desired.
  2. Set up crossover frequency, ƒc, which is typically between 1/5 and 1/20 of ƒSW.
  3. RC can be determined by:
    4. Equation 17. TPS65283 TPS65283-1 eq28_LVSCL3.gif

    where

    • gM is the error amplifier gain (300 µA/V),
    • gmps is the power stage voltage to current conversion gain (7.4 A/V).
  4. Calculate CC by placing a compensation zero at or before the dominant pole (TPS65283 TPS65283-1 eq29_LVSCL3.gif )
    5. Equation 18. TPS65283 TPS65283-1 eq30_LVSCL3.gif
  5. Optional Cb can be used to cancel the 0 from the ESR associated with Cb.
    6. Equation 19. TPS65283 TPS65283-1 eq31_LVSCL3.gif
  6. Type III compensation can be implemented with the addition of one capacitor, C1. This allows for slightly higher loop bandwidths and higher phase margins. If used, C1 is calculated from Equation 20.
    7. Equation 20. TPS65283 TPS65283-1 eq32_LVSCL3.gif

For this design, the calculated values for the compensation components are Rc = 20 kΩ, CC = 3.3 nF, and
Cb = 22 pF.

TPS65283 TPS65283-1 DCDC_Loop_compensation_slvscl3.gifFigure 31. DC-DC Loop Compensation