SLUSF14 august   2023 UCC15241-Q1

PRODUCTION DATA  

  1.   1
  2. Features
  3. Applications
  4. Description
  5. Revision History
  6. Device Comparison
  7. Pin Configuration and Functions
  8. 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 Safety Limiting Values
  9. Safety-Related Certifications
  10. Insulation Characteristics
  11. 10Typical Characteristics
  12. 11Detailed Description
    1. 11.1 Overview
    2. 11.2 Functional Block Diagram
    3. 11.3 Feature Description
      1. 11.3.1 Power Stage Operation
        1. 11.3.1.1 VDD-VEE Voltage Regulation
        2. 11.3.1.2 COM-VEE Voltage Regulation
        3. 11.3.1.3 Power Handling Capability
      2. 11.3.2 Output Voltage Soft Start
      3. 11.3.3 ENA and PG
      4. 11.3.4 Protection Functions
        1. 11.3.4.1 Input Undervoltage Lockout
        2. 11.3.4.2 Input Overvoltage Lockout
        3. 11.3.4.3 Output Undervoltage Protection
        4. 11.3.4.4 Output Overvoltage Protection
        5. 11.3.4.5 Overpower Protection
        6. 11.3.4.6 Overtemperature Protection
    4. 11.4 Device Functional Modes
  13. 12Application and Implementation
    1. 12.1 Application Information
    2. 12.2 Typical Application
      1. 12.2.1 Design Requirements
      2. 12.2.2 Detailed Design Procedure
        1. 12.2.2.1 Capacitor Selection
        2. 12.2.2.2 Single RLIM Resistor Selection
        3. 12.2.2.3 RDR Circuit Component Selection
        4. 12.2.2.4 Feedback Resistors Selection
      3. 12.2.3 Application Curves
    3. 12.3 System Examples
    4. 12.4 Power Supply Recommendations
    5. 12.5 Layout
      1. 12.5.1 Layout Guidelines
      2. 12.5.2 Layout Example
  14. 13Device and Documentation Support
    1. 13.1 Documentation Support
      1. 13.1.1 Related Documentation
    2. 13.2 Receiving Notification of Documentation Updates
    3. 13.3 Support Resources
    4. 13.4 Trademarks
    5. 13.5 Electrostatic Discharge Caution
    6. 13.6 Glossary
  15. 14Mechanical, Packaging, and Orderable Information
  16. 15Tape and Reel Information

Package Options

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

RDR Circuit Component Selection

RLIM1 value is chosen by

Equation 14. RLIM1=VVDD-VEE-VCOM-VEECOUT3×1+COUT3_POS×0.1×VCOM-VEE0.003+ICOM_SOURCE-RLIM_INT
where

∆ICOM_SOURCE=ICOM-VEE-IVDD-COM, when ICOM-VEE>IVDD-COM. Otherwise, ∆ICOM_SOURCE=0A

When the calculated RLIM1 value is higher than 3kΩ, we suggest to use a 3kΩ resistor for RLIM1. The reason is that the extra power loss saving with a >3kΩ resistor is very limited, and a maximum 3kΩ resistor is recommended to reserve enough sourcing capability through RLIM1 for transient event.

RLIM2 value is chosen by

Equation 15. RLIM2=VCOM-VEE-0.5VCOM-VEE(1RLIM_MAX_L-1RLIM_MAX_H)

where RLIM_MAX_L is the smallest value between RLIM_MAX_L1 and RLIM_MAX_L2 in the Single RLIM Resistor Selection Section, and 0.5V represents the diode forward voltage drop of DLIM.

When the calculated RLIM1 and RLIM2 values have large enough difference, the RDR improvement on efficiency will be significant. If RLIM1 and RLIM2 values are close, then single RLIM resistor can be considered to reduce the external components.

The power loss of RLIM1 can be derived as

Equation 16. PRLIM1=VVDD-COM2RLIM1DutyRLIM+(ISINK×VCOM-VEE×RLIM2VCOM-VEE×RLIM2+(VCOM-VEE-0.5)×RLIM1)2×RLIM1

where

Equation 17. ISINK=COUT2×1-COUT2COUT2×1-COUT2+COUT3×1-COUT3-COUT2COUT2+COUT3×QGTotal×fSW+ICOMSINK

The power loss of RLIM2 can be approximated as

Equation 18. PRLIM2=(ISINK×(VCOM-VEE-0.5)×RLIM1VCOM-VEE×RLIM2+(VCOM-VEE-0.5)×RLIM1)2×RLIM2
The maximum voltage rating of diode DLIM needs to consider the highest VVDD-to-VEE. The maximum current rating of DLIM can be chosen based on the derating from the worst-case continuous current, (VCOM-to-VEE – VF_DLIM) / RLIM2, where VF_DLIM is the forward voltage of DLIM. The diode package size is determined based on the power loss in forward conduction, PLoss_DLIM = VF_DLIM x ((VCOM-to-VEE – VF_DLIM) / RLIM2). A Schottky diode is recommended to reduce the power loss.