SNVSCG7 November   2024 LM5190

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Pin Configuration and Functions
  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
    6. 5.6 Typical 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 Hiccup Mode Current Limiting
      18. 6.3.18 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 Buck Inductor
          2. 7.2.1.2.2 Current-Sense Resistance
          3. 7.2.1.2.3 Output Capacitors
          4. 7.2.1.2.4 Input Capacitors
          5. 7.2.1.2.5 Frequency Set Resistor
          6. 7.2.1.2.6 Feedback Resistors
        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

7.1.2 Error Amplifier and Compensation

Figure 7-3 shows a type-ll compensator using a transconductance error amplifier (EA). The dominant pole of the EA open-loop gain is set by the EA output resistance, RO(EA), and effective bandwidth-limiting capacitance, CBW, as shown by Equation 34.

Equation 34. G E A s = - g m ( E A ) × R O ( E A ) 1 + s × R O ( E A ) × C B W

The EA high-frequency pole is neglected in the above expression. Equation 35 calculates the compensator transfer function from output voltage to COMP node, including the gain contribution from the (internal or external) feedback resistor network.

Equation 35. G C O M P s = V C O M P s V L O A D s = - V R E F V L O A D × g m × R O ( E A ) × 1 + s ω Z 1 1 + s ω P 1 × 1 + s ω P 2

where

  • VREF is the feedback voltage reference.
  • gm(EA) is the EA gain transconductance of 1mS.
  • RO(EA) is the error amplifier output impedance of 70MΩ.
Equation 36. ω Z 1 = 1 R C O M P × C C O M P
Equation 37. ω P 1 = 1 R O ( E A ) × C C O M P + C H F + C B W ≅ 1 R O ( E A ) × C C O M P
Equation 38. ω P 2 = 1 R C O M P × C C O M P | | C H F + C B W ≅ 1 R C O M P × C H F

The EA compensation components create a pole close to the origin, a zero, and a high-frequency pole. Typically, RCOMP << RO(EA) and CCOMP >> CBW and CHF, so the approximations are valid.

LM5190 uses FB as the feedback pin for the sensed output voltage. If there is a ground offset between local ground and remote output ground, there is a regulation error due to the sensing error. In this case, AGND pin can be used with FB pin to provide a more accurate regulation. LM5190 allows AGND to deviate as much as +/-300mV typical with respect to PGND.

LM5190 Error Amplifier and Compensation Network Figure 7-3 Error Amplifier and Compensation Network