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

2.2 Energy Consumption

This section describes the energy consumption during each haptic event. The energy consumption for clicks, buzzes, and alerts can be measured in µA-hour and mA-hour.

For the ERM in Figure 2-1, the click duration is 50 ms. The energy consumption of the ERM click can be calculated using the following equation:

Using the previous equation, the energy consumption of an LRA click is 0.57 µAh and for Piezo, the energy consumption is 0.34 µAh.
Table 2-2 Click Energy Consumption Data
Click VDD (V) Mean Current (mA) Time Window (ms) Energy (μAh per Click)
ERM 5 124 50 1.72
LRA 5 52.6 40 0.58
Piezo 5 62.6 19.61 0.34

Conclusion

  • Compared with the ERM, the LRA offers 67% energy savings per click. The LRA has the best efficiency and is better for applications concerned with battery life.
  • The Piezo has quick response time which creates the shortest effects. The short duration of the Piezo click and the quick response time helps contribute to energy savings.