SLVSFF1B December   2021  – December 2022 LM5123-Q1

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Description (continued)
  6. 6 Pin Configuration and Functions
  7. 7 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 Typical Characteristics
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1  Device Enable/Disable (EN, VH Pin)
      2. 8.3.2  High Voltage VCC Regulator (BIAS, VCC Pin)
      3. 8.3.3  Light Load Switching Mode Selection (MODE Pin)
      4. 8.3.4  VOUT Range Selection (RANGE Pin)
      5. 8.3.5  Line Undervoltage Lockout (UVLO Pin)
      6. 8.3.6  Fast Restart using VCC HOLD (VH Pin)
      7. 8.3.7  Adjustable Output Regulation Target (VOUT, TRK, VREF Pin)
      8. 8.3.8  Overvoltage Protection (VOUT Pin)
      9. 8.3.9  Power Good Indicator (PGOOD Pin)
      10. 8.3.10 Dynamically Programmable Switching Frequency (RT)
      11. 8.3.11 External Clock Synchronization (SYNC Pin)
      12. 8.3.12 Programmable Spread Spectrum (DITHER Pin)
      13. 8.3.13 Programmable Soft Start (SS Pin)
      14. 8.3.14 Wide Bandwidth Transconductance Error Amplifier and PWM (TRK, COMP Pin)
      15. 8.3.15 Current Sensing and Slope Compensation (CSP, CSN Pin)
      16. 8.3.16 Constant Peak Current Limit (CSP, CSN Pin)
      17. 8.3.17 Maximum Duty Cycle and Minimum Controllable On-Time Limits
      18. 8.3.18 Deep Sleep Mode and Bypass Operation (HO, CP Pin)
      19. 8.3.19 MOSFET Drivers, Integrated Boot Diode, and Hiccup Mode Fault Protection (LO, HO, HB Pin)
      20. 8.3.20 Thermal Shutdown Protection
    4. 8.4 Device Functional Modes
      1. 8.4.1 Device Status
        1. 8.4.1.1 Shutdown Mode
        2. 8.4.1.2 Configuration Mode
        3. 8.4.1.3 Active Mode
        4. 8.4.1.4 Sleep Mode
        5. 8.4.1.5 Deep Sleep Mode
      2. 8.4.2 Light Load Switching Mode
        1. 8.4.2.1 Forced PWM (FPWM) Mode
        2. 8.4.2.2 Diode Emulation (DE) Mode
        3. 8.4.2.3 Forced Diode Emulation Operation in FPWM Mode
        4. 8.4.2.4 Skip Mode
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
        1. 9.2.2.1 Application Ideas
      3. 9.2.3 Application Curves
    3. 9.3 System Example
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Device Support
      1. 12.1.1 Third-Party Products Disclaimer
    2. 12.2 Receiving Notification of Documentation Updates
    3. 12.3 Support Resources
    4. 12.4 Trademarks
    5. 12.5 Electrostatic Discharge Caution
    6. 12.6 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

Refer to the PDF data sheet for device specific package drawings

Mechanical Data (Package|Pins)
  • RGR|20
Thermal pad, mechanical data (Package|Pins)
Orderable Information

8.3.10 Dynamically Programmable Switching Frequency (RT)

The switching frequency of the device is set by a single RT resistor connected between RT and AGND if no external synchronization clock is applied to the SYNC pin. The resistor value to set the RT switching frequency (RT) is calculated as follows.

Equation 6. R T = 2 . 21 × 10 10 f R T ( t y p i c a l ) - 955

The RT pin is regulated to 0.5 V by an internal RT regulator when the device is in active mode or during the device configuration. The switching frequency can be dynamically programmed during operation as shown in Figure 8-8.

GUID-20200812-CA0I-P6FQ-3NXT-MSWRZDB2W9R0-low.gif Figure 8-8 Frequency Hopping Example