SNVSCE8 July   2024 LM5190-Q1

ADVANCE INFORMATION  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Pin Configuration and Functions
    1. 4.1 Wettable Flanks
  6. 5 Specifications
    1. 5.1 Absolute Maximum Ratings
    2. 5.2 ESD Ratings 
    3. 5.3 Recommended Operating Conditions
    4. 5.4 Thermal Information
    5. 5.5 Electrical Characteristics
  7. 6 Detailed Description
    1. 6.1 Overview
    2. 6.2 Functional Block Diagram
    3. 6.3 Feature Description
      1. 6.3.1  Input Voltage Range (VIN)
      2. 6.3.2  High-Voltage Bias Supply Regulator (VCC, BIAS)
      3. 6.3.3  Precision Enable (EN)
      4. 6.3.4  Power-Good Monitor (PGOOD)
      5. 6.3.5  Switching Frequency (RT)
      6. 6.3.6  Low Dropout Mode
      7. 6.3.7  Dual Random Spread Spectrum (DRSS)
      8. 6.3.8  Soft Start
      9. 6.3.9  Output Voltage Setpoint (FB)
      10. 6.3.10 Minimum Controllable On Time
      11. 6.3.11 Inductor Current Sense (ISNS+, VOUT)
      12. 6.3.12 Voltage Loop Error Amplifier
      13. 6.3.13 Current Monitor, Programmable Current Limit, and Current Loop Error Amplifier (IMON/ILIM, ISET)
      14. 6.3.14 Dual Loop Architecture
      15. 6.3.15 PWM Comparator
      16. 6.3.16 Slope Compensation
      17. 6.3.17 High-Side and Low-Side Gate Drivers (HO, LO)
    4. 6.4 Device Functional Modes
      1. 6.4.1 Sleep Mode
      2. 6.4.2 Forced PWM Mode and Synchronization (FPWM/SYNC)
      3. 6.4.3 Thermal Shutdown
  8. 7 Application and Implementation
    1. 7.1 Application Information
      1. 7.1.1 Power Train Components
        1. 7.1.1.1 Buck Inductor
        2. 7.1.1.2 Output Capacitors
        3. 7.1.1.3 Input Capacitors
        4. 7.1.1.4 Power MOSFETs
        5. 7.1.1.5 EMI Filter
      2. 7.1.2 Error Amplifier and Compensation
    2. 7.2 Typical Applications
      1. 7.2.1 High Efficiency 400kHz CC-CV Regulator
        1. 7.2.1.1 Design Requirements
        2. 7.2.1.2 Detailed Design Procedure
          1. 7.2.1.2.1 Custom Design With Excel Quickstart Tool
          2. 7.2.1.2.2 Recommended Components
        3. 7.2.1.3 Application Curves
    3. 7.3 Power Supply Recommendations
    4. 7.4 Layout
      1. 7.4.1 Layout Guidelines
        1. 7.4.1.1 Power Stage Layout
        2. 7.4.1.2 Gate-Drive Layout
        3. 7.4.1.3 PWM Controller Layout
        4. 7.4.1.4 Thermal Design and Layout
        5. 7.4.1.5 Ground Plane Design
      2. 7.4.2 Layout Example
  9. 8 Device and Documentation Support
    1. 8.1 Device Support
      1. 8.1.1 Development Support
    2. 8.2 Documentation Support
      1. 8.2.1 Related Documentation
        1. 8.2.1.1 PCB Layout Resources
        2. 8.2.1.2 Thermal Design Resources
    3. 8.3 Receiving Notification of Documentation Updates
    4. 8.4 Support Resources
    5. 8.5 Trademarks
    6. 8.6 Electrostatic Discharge Caution
    7. 8.7 Glossary
  10. 9 Revision History
  11. 10Mechanical, Packaging, and Orderable Information
    1. 10.1 Tape and Reel Information

6.3.13 Current Monitor, Programmable Current Limit, and Current Loop Error Amplifier (IMON/ILIM, ISET)

In the current loop, the LM5190-Q1 has a high-gain transconductance amplifier that generates an error current proportional to the difference between the IMON voltage and an internal precision reference (1V). The transconductance of the amplifier is 1000µS. The current loop error amplifier only takes control when the internal minimum function block IMIN selector selects the current from the current loop error amplifier. See Section 6.3.14 for more details regarding the constant-current constant-voltage operation.

LM5190-Q1 Current Loop Functional Block Diagram Figure 6-5 Current Loop Functional Block Diagram

The RIMON is used to programmed the CC regulation target. The CC regulation target is usually defined to be smaller than the maximum current defined by the cycle-by-cycle peak current limit in Inductor Current Sense (ISNS+, VOUT). The RIMON is selected by Equation 9.

Equation 9. RIMON=VrefIRCS×gm_IMON×ICC+IIMON_offset

where

  • VrefI is 1V (typical).
  • RCS is the current sensing resistance.
  • gm_IMON is the current monitor gain of 2µA/mV.
  • ICC is the CC regulation target.
  • IIMON_offset is the IMON offset current of 25µA.

The CIMON is used to form the RC filter with RIMON and filter out the sensed inductor current ripple to the achieve average current regulation. The CIMON also sets the response of the current loop. With RIMON and CIMON selected, IMON/ILIM multi-functional pin can be used as the current monitor when the converter is operating in CV loop. The average inductor current can be read from IMON/ILIM voltage by using Equation 10.

Equation 10. IAVG=VIMONRIMON-IIMON_offsetRCS×gm_IMON

where VIMON is the voltage on IMON/ILIM pin and IAVG is the average inductor current. The DC offset current is introduced at IMON/ILIM pin to raise the no-load signal above the possible ground noise floor.

ISET can be used to dynamically program the CC regulation current. An external voltage forced at ISET can set the CC regulation current by Equation 11.

Equation 11. VISET=RIMON×(ICCset×RCS×gmIMON+IIMON_offset)

where ICCset is the desired average current to be programmed by ISET. ISET is only functional when ISET voltage is smaller than VrefI (1V typical). ISET has an internal current source of 10µA typical so ISET can be used with a capacitor at the pin to achieve the current soft start during CC transient such as super capacitor and battery charging conditions.