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

3 Energy Consumption Comparisons for ERM, LRA and Piezo

In this section, we summarize more energy consumption data for the ERM, LRA, and Piezo with different types of haptic effects.

Table 3-1 Energy Consumption Comparisons Data
Piezo LRA ERM
Effect Duration (ms) Consumption (μAh) Accelerate (g) Duration (ms) Consumption (μAh) Accelerate (g) Duration (ms) Consumption (μAh) Accelerate (g)
Bump 13.3 0.31 0.96 40 0.30 0.93 39 1.14 0.89
Click 19.61 0.34 0.921 51.3 0.57 0.903 50 1.72 0.90
Pulse 48 0.90 0.91 91 0.68 0.95 94 1.72 0.92
Alert 60 1.18 0.92 75 0.47 0.91 78.70 2.00 0.96
Buzz 609 11.4 0.90 752 3.38 1.00 609 11.41 0.93

Figure 3-1 converts this data to a bar graph:

GUID-20211119-SS0I-ZVV8-2WJT-MDTC9P6CRF06-low.gif Figure 3-1 Energy Consumption of Piezo, LRA, and ERM

Table 3-1 and Figure 3-1 illustrate the following conclusions:

  • The Piezo consumes the least amount of energy on short effects compared to the other actuators
  • When playing longer, constant-acceleration effects, Piezo consumes the same amount of energy as ERM
  • The LRA can save 60%-80% energy compared to ERM

The actuator is loaded with a 100 g metal mass to simulate a smartphone. Section 6Appendix B shows the test condition, and Appendix C shows how to use the effects data in Table 3-2 to calculate each scenario for a smartphone.

Table 3-2 Phone Scenarios
Energy Consumption (uAh)
Usage Piezo LRA ERM
Phone Call (1x) 140.2 46.31 154.22
15x 2103 694.62 2313.54
Text Message (1x) 72.74 115.87 352.40
15x 1091.04 1737.96 5286
Reply to an Email 106.74 172.86 524.6
5x 533.68 864.32 2623
Reminder (1x) 125.84 38.5 134.18
10x 1258.4 385 1341.8
Games - 60 minutes 2628 2235.40 6979.30
Social Media 60 - minutes 2624.69 2242.46 7087.40
Standby 240 45.6 45.6
Total 15204.41 11744.05 36760.8
Total/1200 mAh Battery (%) 1.267 0.979 3.06

It is very clear that LRA and Piezo have big energy advantages for portable applications. For the smartphone application, an ERM consumes nearly two times more energy than LRA and Piezo. The battery of a smart-watch is usually much smaller, so the proportion of total energy consumption of haptics is more significant. In this case, the energy savings of TI haptics solution is more significant.