SNVS477C February   2007  – January 2016 LM5109B

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Pin Configuration and 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 Switching 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 Start-Up and UVLO
      2. 7.3.2 Level Shift
      3. 7.3.3 Output Stages
    4. 7.4 Device Functional Modes
    5. 7.5 HS Transient Voltages Below Ground
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1 Select Bootstrap and VDD Capacitor
        2. 8.2.2.2 Select External Bootstrap Diode and Its Series Resistor
        3. 8.2.2.3 Selecting External Gate Driver Resistor
        4. 8.2.2.4 Estimate the Driver Power Loss
      3. 8.2.3 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 Documentation Support
      1. 11.1.1 Related Documentation
    2. 11.2 Community Resources
    3. 11.3 Trademarks
    4. 11.4 Electrostatic Discharge Caution
    5. 11.5 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

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

9 Power Supply Recommendations

The recommended bias supply voltage range for LM5109B is from 8 V to 14 V. The lower end of this range is governed by the internal undervoltage lockout (UVLO) protection feature of the VDD supply circuit blocks. The upper end of this range is driven by the 18-V absolute maximum voltage rating of the VDD. TI recommends keeping a 4-V margin to allow for transient voltage spikes.

The UVLO protection feature also involves a hysteresis function. This means that once the device is operating in normal mode, if the VDD voltage drops, the device continues to operate in normal mode as long as the voltage drop does not exceed the hysteresis specification, VDDH. If the voltage drop is more than hysteresis specification, the device shuts down. Therefore, while operating at or near the 8-V range, the voltage ripple on the auxiliary power supply output must be smaller than the hysteresis specification of LM5109B to avoid triggering device-shutdown.

A local bypass capacitor must be placed between the VDD and GND pins. And this capacitor must be located as close to the device as possible. A low-ESR, ceramic surface mount capacitor is recommended. TI recommends using 2 capacitors across VDD and GND: a 100-nF, ceramic surface-mount capacitor for high-frequency filtering placed very close to VDD and GND pin, and another surface-mount capacitor, 220-nF to 10-µF, for IC bias requirements. In a similar manner, the current pulses delivered by the HO pin are sourced from the HB pin. Therefore a 22-nF to 220-nF local decoupling capacitor is recommended between the HB and HS pins.