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

2.3 Current Versus Acceleration

There is another parameter that measures the ratio of the current to the acceleration. It shows which actuator provides the best acceleration but consumes the least amount of current. This method is used for a continuous and constant acceleration effect.

GUID-20211119-SS0I-6WST-5R9J-GRKR8FVFHRVM-low.gifFigure 2-2 Buzz Energy Consumption Measurements

Figure 2-2 shows the energy consumption for the ERM, LRA, and Piezo during a buzz effect. A buzz waveform is a continuous waveform with constant acceleration. The actuators are compared with different acceleration forces by using a new energy metric called “mA/g”, which is the current per unit of acceleration. This metric normalizes the current per unit of acceleration.

Table 2-3 Buzz Energy Consumption Data
BuzzMean Current (mA)Acceleration (g)Energy (mA/g)
ERM58.30.9162.1
LRA52.21.6332.0
Piezo67.40.9372.4

Conclusion

  • The LRA consumes the least current per g, which means it is the best actuator for long duration effects.
  • The ERM and Piezo nearly consume the same current per g in the long time effects.

See Section 5 for the energy consumption of a click tested on more kinds of actuators. The data is evaluated on the DRV2603EVM-CT. However, there is no significant difference when testing on the DRV2604EVM-CT, and therefore still representative of both DRV260x and DRV262x driver families.