SNAS491B February   2010  – February 2018 LM48580

PRODUCTION DATA.  

  1. Features
  2. Applications
  3. Description
    1.     Device Images
      1.      Typical Application
  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: VDD = 3.6 V
    6. 6.6 Typical Performance Characteristics
  7. Parameter Measurement Information
  8. Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Class H Operation
      2. 8.3.2 Properties of Piezoelectric Elements
      3. 8.3.3 Differential Amplifier Explanation
      4. 8.3.4 Thermal Shutdown
      5. 8.3.5 Gain Setting
    4. 8.4 Device Functional Modes
      1. 8.4.1 Shutdown Function
  9. Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
        1. 9.2.1.1 Proper Selection of External Components
          1. 9.2.1.1.1 Boost Converter Capacitor Selection
      2. 9.2.2 Detailed Design Procedure
        1. 9.2.2.1 Boost Converter Output Capacitor Selection
          1. 9.2.2.1.1 Inductor Selection
          2. 9.2.2.1.2 Diode Selection
        2. 9.2.2.2 Application Curves
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Device Support
      1. 12.1.1 Development Support
        1. 12.1.1.1 Third-Party Products Disclaimer
    2. 12.2 Receiving Notification of Documentation Updates
    3. 12.3 Community Resources
    4. 12.4 Trademarks
    5. 12.5 Electrostatic Discharge Caution
    6. 12.6 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

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

Properties of Piezoelectric Elements

Piezoelectric elements such as ceramic speakers or piezoelectric haptic actuators are capacitive in nature. Due to their capacitive nature, piezoelectric elements appear as low impedance loads at high frequencies (typically above 5 kHz). A resistor in series with the piezoelectric element is required to ensure the amplifier does not see a short at high frequencies.

The value of the series resistor depends on the capacitance of the element, the frequency content of the output signal, and the desired frequency response. Higher valued resistors minimize power dissipation at high frequencies, but also impacts the frequency response. This configuration is suited for use with haptic actuators, where the majority of the signal content is typically below 2 kHz. Conversely, lower valued resistors maximize frequency response, while increasing power dissipation at high frequency. This configuration is ideal for ceramic speaker applications, where high frequency audio content needs to be reproduced. Resistor values are typically between 10 Ω and 20 Ω.