SNVS617H April   2009  – November 2014 LM25011 , LM25011-Q1

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Typical Application
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
    1.     Pin Functions
  6. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 Handling Ratings: LM25011
    3. 6.3 Handling Ratings: LM25011-Q1
    4. 6.4 Recommended Operating Conditions
    5. 6.5 Thermal Information
    6. 6.6 Electrical Characteristics
    7. 6.7 Typical Characteristics
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Control Circuit Overview
      2. 7.3.2 On-Time Timer
      3. 7.3.3 Current Limit
      4. 7.3.4 Ripple Requirements
      5. 7.3.5 N-Channel Buck Switch and Driver
      6. 7.3.6 Soft-Start
      7. 7.3.7 Power Good Output (PGD)
      8. 7.3.8 Thermal Shutdown
    4. 7.4 Device Functional Modes
      1. 7.4.1 Shutdown Function
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 LM25011 Example Circuit
        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 External Components
        3. 8.2.1.3 Application Curves
      2. 8.2.2 Output Ripple Control
        1. 8.2.2.1 Option A: Lowest Cost Configuration
        2. 8.2.2.2 Option B: Intermediate VOUT Ripple Configuration
        3. 8.2.2.3 Option C: Minimum VOUT Ripple Configuration
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
    3. 10.3 Power Dissipation
  11. 11Device and Documentation Support
    1. 11.1 Custom Design with WEBENCH Tools
    2. 11.2 Receiving Notification of Documentation Updates
    3. 11.3 Related Links
    4. 11.4 Trademarks
    5. 11.5 Electrostatic Discharge Caution
    6. 11.6 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

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

7.3.7 Power Good Output (PGD)

The Power Good output (PGD) indicates when the voltage at the FB pin is close to the internal 2.51-V reference voltage. The rising threshold at the FB pin for the PGD output to switch high is 95% of the internal reference. The falling threshold for the PGD output to switch low is approximately 3.3% below the rising threshold.

The PGD pin is internally connected to the drain of an N-channel MOSFET switch. An external pull-up resistor (RPGD), connected to an appropriate voltage not exceeding 7 V, is required at PGD to indicate the LM25011 status to other circuitry. When PGD is low, the pin voltage is determined by the current into the pin. See Figure 7, PGD Low Voltage vs Sink Current.

Upon powering up the LM25011, the PGD pin is high until the voltage at VIN reaches 2 V, at which time PGD switches low. As VIN is increased, PGD stays low until the output voltage takes the voltage at the FB pin above 95% of the internal reference voltage, at which time PGD switches high. As VIN is decreased (during shutdown), PGD remains high until either the voltage at the FB pin falls below approximately 92% of the internal reference or when VIN falls below its lower UVLO threshold, whichever occurs first. PGD then switches low, and remains low until VIN falls below 2 V, at which time PGD switches high. If the LM25011 is used as a tracking regulator (see the Soft-Start section), the PGD output is high as long as the voltage at the FB pin is above the thresholds mentioned above.