SLUSB56B November   2012  – April 2019 TPS53819A

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      Simplified Application
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
    1.     Pin Functions
  6. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics
    6. 6.6 Timing Requirements
    7. 6.7 Switching Characteristics
    8. 6.8 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  Enable and Soft-Start
      2. 7.3.2  Adaptive On-Time Control
      3. 7.3.3  Zero Crossing Detection
      4. 7.3.4  Output Discharge Control
      5. 7.3.5  Low-Side Driver
      6. 7.3.6  High-Side Driver
      7. 7.3.7  Power Good
      8. 7.3.8  Current Sense and Overcurrent Protection
      9. 7.3.9  Overvoltage and Undervoltage Protection
      10. 7.3.10 Out-of-Bound Protection
      11. 7.3.11 UVLO Protection
      12. 7.3.12 Thermal Shutdown
    4. 7.4 Device Functional Modes
      1. 7.4.1 Light-Load Condition in Auto-Skip Operation (Eco-mode)
      2. 7.4.2 Forced Continuous Conduction Mode
      3. 7.4.3 D-CAP2™ Mode
    5. 7.5 Programming
      1. 7.5.1 PMBus General Descriptions
      2. 7.5.2 PMBus Slave Address Selection
      3. 7.5.3 PMBus Address Selection
      4. 7.5.4 Supported Formats
        1. 7.5.4.1 Direct Format: Write
        2. 7.5.4.2 Combined Format: Read
        3. 7.5.4.3 Stop-Separated Reads
      5. 7.5.5 Supported PMBus Commands
      6. 7.5.6 Unsupported PMBus Commands
    6. 7.6 Register Maps
      1. 7.6.1  OPERATION [01h] (R/W Byte)
      2. 7.6.2  ON_OFF_CONFIG [02h] (R/W Byte)
      3. 7.6.3  WRITE_PROTECT [10h] (R/W Byte)
      4. 7.6.4  CLEAR_FAULTS [03h] (Send Byte)
      5. 7.6.5  STORE_DEFAULT_ALL [11h] (Send Byte)
      6. 7.6.6  RESTORE_DEFAULT_ALL [12h] (Send Byte)
      7. 7.6.7  STATUS_WORD [79h] (Read Word)
      8. 7.6.8  CUSTOM_REG (MFR_SPECIFIC_00) [D0h] (R/W Byte)
      9. 7.6.9  DELAY_CONTROL (MFR_SPECIFIC_01) [D1h] (R/W Byte)
      10. 7.6.10 MODE_SOFT_START_CONFIG (MFR_SPECIFIC_02) [D2h] (R/W Byte)
      11. 7.6.11 FREQUENCY_CONFIG (MFR_SPECIFIC_03) [D3h] (R/W Byte)
      12. 7.6.12 VOUT_ADJUSTMENT (MFR_SPECIFIC_04) [D4h] (R/W Byte)
      13. 7.6.13 Output Voltage Fine Adjustment Soft Slew Rate
      14. 7.6.14 VOUT_MARGIN (MFR_SPECIFIC_05) [D5h] (R/W Byte)
      15. 7.6.15 Output Voltage Margin Adjustment Soft-Slew Rate
      16. 7.6.16 UVLO_THRESHOLD (MFR_SPECIFIC_06) [D6h]
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1  Custom Design With WEBENCH® Tools
        2. 8.2.2.2  Switching Frequency
        3. 8.2.2.3  Inductor (L1)
        4. 8.2.2.4  Output Capacitors (C10, C11, C12, C13, C14)
        5. 8.2.2.5  Input Capacitors (C1, C2, C3, C4, C5)
        6. 8.2.2.6  MOSFET (Q1, Q2)
        7. 8.2.2.7  VREG Bypass Capacitor (C18)
        8. 8.2.2.8  VDD Bypass Capacitor (C19)
        9. 8.2.2.9  VBST Capacitor (C7)
        10. 8.2.2.10 Snubber (C8 and R9)
        11. 8.2.2.11 Feedback Resistance, RFBH and RFBL (R17 and R18)
        12. 8.2.2.12 Overcurrent Limit (OCL) Setting Resistance (R10)
        13. 8.2.2.13 PMBus Device Address (R3 and R4)
        14. 8.2.2.14 PGOOD Pullup Resistor (R2)
        15. 8.2.2.15 SCL and SDA Pulldown Resistors (R14 and R15)
        16. 8.2.2.16 PMBus Pullup Resistors
      3. 8.2.3 Application Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Device Support
      1. 11.1.1 Development Support
        1. 11.1.1.1 Custom Design With WEBENCH® Tools
    2. 11.2 Receiving Notification of Documentation Updates
    3. 11.3 Community Resources
    4. 11.4 Trademarks
    5. 11.5 Electrostatic Discharge Caution
    6. 11.6 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

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

8.2.2.4 Output Capacitors (C10, C11, C12, C13, C14)

Determine the output capacitance to meet the load transient, ripple requirements, and to meet small-signal stability as shown in Equation 12.

Equation 12. TPS53819A q_5timesfc2_lusau9.gif

where

  • G =0.25
  • RC1 × CC1 time constant can be referred to Table 1
  • D is the duty cycle

Based on Equation 12, the value of COUT to ensure small signal stability can be calculated using Equation 13 and Equation 14. These equations assume MLCC are used and the ESR effects are negligible. If a high ESR output capacitor is used, the effects may reduce the minimum and maximum capacitance. In the design example using Table 1 for 425-kHz switching frequency, the time constant is 62 μs. The recommended minimum capacitance for a design with an 8-V minimum input voltage is 260 μF. The recommended maximum capacitance for design with a 14-V maximum input voltage is 4842 μF.

Equation 13. TPS53819A q_cout1_lusau9.gif
Equation 14. TPS53819A q_cout2_lusau9.gif

Select a larger output capacitance to decrease the output voltage change that occurs during a load transient and the output voltage ripple.

The minimum output capacitance to meet an output voltage ripple requirement can be calculated with Equation 15. In the example the minimum output capacitance for 12 mVPP ripple is 162 μF. If non ceramic capacitors are used Equation 16 calculates the maximum equivalent series resistance (ESR) of the output capacitor to meet the ripple requirement. Equation 17 calculates the required RMS current rating for the output capacitor. In this example with 12-V nominal input voltage it is 1.77 A. Finally the output capacitor must be rated for the output voltage.

Equation 15. TPS53819A q_cout3_lusau9.gif
Equation 16. TPS53819A q_esr_lusau9.gif
Equation 17. TPS53819A q_icoutrms_lusau9.gif

This example uses five 1210, 100-μF, 6.3-V, X5R ceramic capacitors with 2 mΩ of ESR. From the data sheet the estimated DC derating of 95% and AC derating of 70% for a total of 66.5% at room temperature. The total output capacitance is approximately 332.5 μF.