SLOA194A May   2014  – January 2022 DRV2603 , DRV2604 , DRV2604L , DRV2605 , DRV2605L , DRV2605L-Q1 , DRV2624 , DRV2625 , DRV2667

 

  1.   Trademarks
  2. 1Introduction
    1. 1.1 Eccentric Rotating Mass
    2. 1.2 Linear Resonant Actuator
    3. 1.3 Piezo Actuator
  3. 2How to Measure Energy
    1. 2.1 Current Consumption
    2. 2.2 Energy Consumption
    3. 2.3 Current Versus Acceleration
  4. 3Energy Consumption Comparisons for ERM, LRA and Piezo
  5. 4Energy Consumption Advantage of DRV260x and DRV262x Drivers
  6. 5Appendix A Energy Consumption of Actuators
  7. 6Appendix B. Test Setup Picture
  8. 7Appendix C. Energy Consumption Calculation for Smartphone Scenarios
  9. 8Revision History

1.1 Eccentric Rotating Mass

An ERM is a DC motor with an off-center mass that spins to create vibrations. When the ERM rotates, the off-center mass results in a centripetal force; this kind of centripetal force causes displacement of the motor. People perceive this displacement as a vibration. The ERM vibrates because of rotation forces so there is acceleration on two axes (X, Y, or Z axis). This creates losses in unintentional axes in some applications.

Advantages:

  • Easy to drive
  • Low cost
  • Flexible form factor (bar or coin)

Disadvantages:

  • Slow response
  • Acceleration is correlated with angular frequency(ERM)
  • High energy consumption