SLUS772G MARCH   2008  – June 2020 TPS40210 , TPS40211

PRODUCTION DATA.  

  1. Features
  2. Applications
  3. Description
    1.     Device Images
      1.      Simplified Schematic
  4. Revision History
  5. Pin Configuration and Functions
    1.     Pin Functions
  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 Typical Characteristics
  7. Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1  Soft Start
      2. 7.3.2  BP Regulator
      3. 7.3.3  Shutdown (DIS/EN Pin)
      4. 7.3.4  Minimum On-Time and Off-Time Considerations
      5. 7.3.5  Setting the Oscillator Frequency
      6. 7.3.6  Synchronizing the Oscillator
      7. 7.3.7  Current Sense and Overcurrent
      8. 7.3.8  Current Sense and Subharmonic Instability
      9. 7.3.9  Current Sense Filtering
      10. 7.3.10 Control Loop Considerations
      11. 7.3.11 Gate Drive Circuit
      12. 7.3.12 TPS40211
    4. 7.4 Device Functional Modes
      1. 7.4.1 Operation Near Minimum Input Voltage
      2. 7.4.2 Operation With DIS/EN Pin
  8. Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Applications
      1. 8.2.1 12-V to 24-V Nonsynchronous Boost Regulator
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
          1. 8.2.1.2.1  Custom Design with WEBENCH Tools
          2. 8.2.1.2.2  Duty Cycle Estimation
          3. 8.2.1.2.3  Inductor Selection
          4. 8.2.1.2.4  Rectifier Diode Selection
          5. 8.2.1.2.5  Output Capacitor Selection
          6. 8.2.1.2.6  Input Capacitor Selection
          7. 8.2.1.2.7  Current Sense and Current Limit
          8. 8.2.1.2.8  Current Sense Filter
          9. 8.2.1.2.9  Switching MOSFET Selection
          10. 8.2.1.2.10 Feedback Divider Resistors
          11. 8.2.1.2.11 Error Amplifier Compensation
          12. 8.2.1.2.12 RC Oscillator
          13. 8.2.1.2.13 Soft-Start Capacitor
          14. 8.2.1.2.14 Regulator Bypass
          15. 8.2.1.2.15 Bill of Materials
        3. 8.2.1.3 Application Curves
      2. 8.2.2 12-V Input, 700-mA LED Driver, Up to 35-V LED String
        1. 8.2.2.1 Design Requirements
        2. 8.2.2.2 Detailed Design Procedure
  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 Third-Party Products Disclaimer
      2. 11.1.2 Related Devices
      3. 11.1.3 Development Support
        1. 11.1.3.1 Custom Design with WEBENCH Tools
    2. 11.2 Documentation Support
      1. 11.2.1 Related Documentation
    3. 11.3 Related Links
    4. 11.4 Receiving Notification of Documentation Updates
    5. 11.5 Trademarks
    6. 11.6 Electrostatic Discharge Caution
    7. 11.7 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

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

Error Amplifier Compensation

Compensation selection can be done with aid of WEBENCH to select compensation components or with the aid of the average Spice model to simulate the open loop modulator and power stage gain. Alternatively, the following procedure gives a good starting point.

While current mode control typically only requires Type II compensation, it is desirable to layout for Type III compensation to increase flexibility during design and development. Current mode control boost converters have higher gain with higher output impedance, so it is necessary to calculate the control loop gain at the maximum output impedance, estimated by Equation 58.

Equation 58. TPS40210 TPS40211 q_routmax_lus772.gif

The transconductance of the TPS40210 current mode control can be estimated by Equation 59.

Equation 59. TPS40210 TPS40211 q_gm_lus772.gif

The maximum output impedance ZOUT, can be estimated by Equation 60.

Equation 60. TPS40210 TPS40211 q_zoutf_lus772.gif
Equation 61. TPS40210 TPS40211 q_zoutfco_lus772.gif

At the desired crossover frequency (fL) of 30 kHz, ZOUT becomes 0.146 Ω.

The modulator gain at the desired cross-over can be estimated by Equation 62.

Equation 62. TPS40210 TPS40211 q_kco_lus772.gif

The feedback compensation network needs to be designed to provide an inverse gain at the cross-over frequency for unity loop gain. This sets the compensation mid-band gain at a value calculated in Equation 63.

Equation 63. TPS40210 TPS40211 q_kcomp_lus772.gif

To set the mid-band gain of the error amplifier to KCOMP, use Equation 64.

Equation 64. TPS40210 TPS40211 q_r4_lus772.gif

R4 = 18.7 kΩ selected.

Place the zero at 1/10th of the desired cross-over frequency.

Equation 65. TPS40210 TPS40211 q_c2_lus772.gif

C2 = 2200 pF selected.

Place a high-frequency pole at about five times the desired cross-over frequency and less than one-half the unity gain bandwidth of the error amplifier:

Equation 66. TPS40210 TPS40211 q_c4_lus772.gif
Equation 67. TPS40210 TPS40211 q_c4gt_lus772.gif

C4 = 47 pF selected.