SNVS288K September   2004  – September 2018 LM2734

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      Typical Application Circuit
      2.      Efficiency vs Load Current VIN = 5 V, VOUT = 3.3 V
  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 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics
    6. 6.6 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 Output Overvoltage Protection
      2. 7.3.2 Undervoltage Lockout
      3. 7.3.3 Current Limit
      4. 7.3.4 Thermal Shutdown
    4. 7.4 Device Functional Modes
      1. 7.4.1 Enable Pin / Shutdown Mode
      2. 7.4.2 Soft Start
  8. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 Boost Function
    2. 8.2 Typical Applications
      1. 8.2.1  LM2734X (1.6 MHz) VBOOST Derived from VIN 5V to 1.5 V/1 A
        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 Inductor Selection
          3. 8.2.1.2.3 Input Capacitor
          4. 8.2.1.2.4 Output Capacitor
          5. 8.2.1.2.5 Catch Diode
          6. 8.2.1.2.6 Boost Diode
          7. 8.2.1.2.7 Boost Capacitor
          8. 8.2.1.2.8 Output Voltage
        3. 8.2.1.3 Application Curves
      2. 8.2.2  LM2734X (1.6 MHz) VBOOST Derived from VOUT 12 V to 3.3 V /1 A
        1. 8.2.2.1 Design Requirements
        2. 8.2.2.2 Detailed Design Procedure
        3. 8.2.2.3 Application Curves
      3. 8.2.3  LM2734X (1.6 MHz) VBOOST Derived from VSHUNT 18 V to 1.5 V /1 A
        1. 8.2.3.1 Design Requirements
        2. 8.2.3.2 Detailed Design Procedure
        3. 8.2.3.3 Application Curves
      4. 8.2.4  LM2734X (1.6 MHz) VBOOST Derived from Series Zener Diode (VIN) 15 V to 1.5 V / 1 A
        1. 8.2.4.1 Design Requirements
        2. 8.2.4.2 Detailed Design Procedure
        3. 8.2.4.3 Application Curves
      5. 8.2.5  LM2734X (1.6 MHz) VBOOST Derived from Series Zener Diode (VOUT) 15 V to 9 V /1 A
        1. 8.2.5.1 Design Requirements
        2. 8.2.5.2 Detailed Design Procedure
        3. 8.2.5.3 Application Curves
      6. 8.2.6  LM2734Y (550 kHz) VBOOST Derived from VIN 5 V to 1.5 V / 1 A
        1. 8.2.6.1 Design Requirements
        2. 8.2.6.2 Detailed Design Procedure
        3. 8.2.6.3 Application Curves
      7. 8.2.7  LM2734Y (550 kHz) VBOOST Derived from VOUT 12 V to 3.3 V / 1 A
        1. 8.2.7.1 Design Requirements
        2. 8.2.7.2 Detailed Design Procedure
        3. 8.2.7.3 Application Curves
      8. 8.2.8  LM2734Y (550 kHz) VBOOST Derived from VSHUNT 18 V to 1.5 V / 1 A
        1. 8.2.8.1 Design Requirements
        2. 8.2.8.2 Detailed Design Procedure
        3. 8.2.8.3 Application Curves
      9. 8.2.9  LM2734Y (550 kHz) VBOOST Derived from Series Zener Diode (VIN) 15 V to 1.5 V / 1 A
        1. 8.2.9.1 Design Requirements
        2. 8.2.9.2 Detailed Design Procedure
        3. 8.2.9.3 Application Curves
      10. 8.2.10 LM2734Y (550 kHz) VBOOST Derived from Series Zener Diode (VOUT) 15 V to 9 V / 1 A
        1. 8.2.10.1 Design Requirements
        2. 8.2.10.2 Detailed Design Procedure
        3. 8.2.10.3 Application Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Development Support
      1. 11.1.1 Custom Design With WEBENCH® Tools
    2. 11.2 Receiving Notification of Documentation Updates
    3. 11.3 Community Resources
    4. 11.4 Third-Party Products Disclaimer
    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

8.2.1.2.4 Output Capacitor

The output capacitor is selected based upon the desired output ripple and transient response. The initial current of a load transient is provided mainly by the output capacitor. The output ripple of the converter is:

Equation 22. LM2734 20102339.gif

When using MLCCs, the ESR is typically so low that the capacitive ripple may dominate. When this occurs, the output ripple will be approximately sinusoidal and 90° phase shifted from the switching action. Given the availability and quality of MLCCs and the expected output voltage of designs using the LM2734 device, there is really no need to review any other capacitor technologies. Another benefit of ceramic capacitors is their ability to bypass high frequency noise. A certain amount of switching edge noise will couple through parasitic capacitances in the inductor to the output. A ceramic capacitor will bypass this noise while a tantalum will not. Because the output capacitor is one of the two external components that control the stability of the regulator control loop, most applications will require a minimum at 10 µF of output capacitance. Capacitance can be increased significantly with little detriment to the regulator stability. Like the input capacitor, recommended multilayer ceramic capacitors are X7R or X5R. Again, verify actual capacitance at the desired operating voltage and temperature.

Check the RMS current rating of the capacitor. The RMS current rating of the capacitor chosen must also meet the following condition:

Equation 23. LM2734 20102340.gif