SLVSG70 april   2023 TPS62902-Q1

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Device Comparison Table
  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  Mode Selection and Device Configuration MODE/S-CONF
      2. 8.3.2  Adjustable VO Operation (External Voltage Divider)
      3. 8.3.3  Selectable VO Operation (VSET and Internal Voltage Divider)
      4. 8.3.4  Soft Start and Tracking (SS/TR)
        1. 8.3.4.1 Tracking Function
      5. 8.3.5  Smart Enable with Precise Threshold
      6. 8.3.6  Power Good (PG)
      7. 8.3.7  Output Discharge Function
      8. 8.3.8  Undervoltage Lockout (UVLO)
      9. 8.3.9  Current Limit and Short-Circuit Protection
      10. 8.3.10 High Temperature Specifications
      11. 8.3.11 Thermal Shutdown
    4. 8.4 Device Functional Modes
      1. 8.4.1 Forced Pulse Width Modulation (FPWM) Operation
      2. 8.4.2 Power Save Mode Operation (Auto PFM and PWM)
      3. 8.4.3 AEE (Automatic Efficiency Enhancement)
      4. 8.4.4 100% Duty-Cycle Operation
      5. 8.4.5 Starting into a Prebiased Load
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application with Adjustable Output Voltage
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
        1. 9.2.2.1 Custom Design With WEBENCH® Tools
        2. 9.2.2.2 Programming the Output Voltage
        3. 9.2.2.3 External Component Selection
          1. 9.2.2.3.1 Output Filter and Loop Stability
          2. 9.2.2.3.2 Inductor Selection
          3. 9.2.2.3.3 Capacitor Selection
            1. 9.2.2.3.3.1 Output Capacitor
            2. 9.2.2.3.3.2 Input Capacitor
            3. 9.2.2.3.3.3 Soft-Start Capacitor
      3. 9.2.3 Application Curves
        1. 9.2.3.1 Application Curves Vout = 1.8 V
        2. 9.2.3.2 Application Curves Vout = 1.2 V
        3. 9.2.3.3 Application Curves Vout = 0.6 V
    3. 9.3 Typical Application with Selectable VOUT using VSET
      1. 9.3.1 Design Requirements
      2. 9.3.2 Detailed Design Procedure
        1. 9.3.2.1 Programming the Output Voltage
      3. 9.3.3 Application Curves
        1. 9.3.3.1 Application Curves Vout = 5 V
        2. 9.3.3.2 Application Curves Vout = 3.3 V
    4. 9.4 System Examples
      1. 9.4.1 LED Power Supply
      2. 9.4.2 Powering Multiple Loads
      3. 9.4.3 Voltage Tracking
      4. 9.4.4 Inverting Buck-Boost (IBB)
    5. 9.5 Power Supply Recommendations
    6. 9.6 Layout
      1. 9.6.1 Layout Guidelines
      2. 9.6.2 Layout Example
      3. 9.6.3 Thermal Considerations
  10. 10Device and Documentation Support
    1. 10.1 Device Support
      1. 10.1.1 Third-Party Products Disclaimer
      2. 10.1.2 Development Support
        1. 10.1.2.1 Custom Design With WEBENCH® Tools
    2. 10.2 Documentation Support
      1. 10.2.1 Related Documentation
    3. 10.3 Receiving Notification of Documentation Updates
    4. 10.4 Support Resources
    5. 10.5 Trademarks
    6. 10.6 Electrostatic Discharge Caution
    7. 10.7 Glossary
  11. 11Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information
9.2.2.3.1 Output Filter and Loop Stability

The TPS62902-Q1 is designed to be stable with a range of L-C filter combinations. The LC output filters inductance and capacitance have to be considered together, creating a double pole responsible for the corner frequency of the converter using Equation 12.

Equation 12. fLC=12π L ×C

Proven nominal values for inductance and ceramic capacitance are given in Table 9-3 and are recommended for use with the effective capacitance considered to vary by +20% and –50%. Different values can work, but care has to be taken on the loop stability, which is affected. More information including a detailed LC stability matrix can be found in the Optimizing the TPS62130/40/50/60 Output Filter application report.

Table 9-3 Recommended LC Output Filter Combinations
4.7 µF 10 µF 22 µF 47 µF 100 µF 200 µF
1 µH √ √(1) √ √ √(3)
1.5 µH √ √ √ √(3)
2.2 µH √ √(2) √ √(3)
3.3 µH √ √ √ √
(1) This LC combination is the standard value and recommended for most applications with 2.5-MHz switching frequency.
(2) This LC combination is the standard value and recommended for most applications with 1-MHz switching frequency.
(3) Output capacitance must have a ESR of ≥ 10 mΩ for stable operation, see Section 9.4.2.

The TPS62902-Q1 includes an internal 3-pF feedforward capacitor, connected between the VOS and FB pins. This capacitor impacts the frequency behavior and sets a pole and zero in the control loop with the resistors of the feedback divider, per Equation 13 and Equation 14:

Equation 13. f z e r o = 1 2 π   ×   R 1   ×   3 p F
Equation 14. f p o l e = 1 2 π   ×   3 p F   ×   1 R 1   ×   1 R 2

Although the TPS62902-Q1 devices are stable without the pole and zero being in a particular location, an external feedforward capacitor can be added to adjust their locations to the specific needs of the application can provide better performance in power save mode, improved transient response, or both. A more detailed discussion on the optimization for stability versus transient response can be found in the Optimizing Transient Response of Internally Compensated DC-DC Converters and Feedforward Capacitor to Improve Stability and Bandwidth of TPS621/821-Family application reports.