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

1.3 Piezo Actuator

Piezoelectric materials are a type of materials that will deform (move) when a voltage is applied. Piezo haptic actuators enable precise actuation for high-definition haptics which corresponds to a faster start-up time, a higher bandwidth of drive voltage, lower audible noise, and stronger vibrations compared with ERMs and LRAs.

Piezo actuators come in two types: single-layer or multi-layer. The single-layer Piezo requires higher voltage to move some distance because Piezo actuators are capacitive loads. Multi-layer Piezo requires lower voltages but higher current. The DRV2667 can drive Piezo actuators up to 200 Vpp.

Piezo actuators vibrate when a voltage is applied, which causes a deformation in the Piezo material. The deformation in the material creates a flexing motion, which results in acceleration in one direction. Overall, Piezo actuators have stronger acceleration, faster response times, and lower energy consumption.

Advantages:

  • Quick response time
  • Wide frequency bandwidth
  • Larger acceleration
  • Higher efficiency
  • Lower audible noise
  • Available in a variety of shapes and sizes
  • Flexible mounting options

Disadvantages:

  • Needs higher voltages to drive
  • More expensive compared to LRA and ERM

Table 1-1 shows a comparison of ERM, LRA and Piezo actuator.

Table 1-1 Actuator Comparisons
Attribute ERM LRA Low Layer Count Piezo High Layer Count Piezo
Performance Good Better Best Best
Acceleration (g) ~1 ~1-2 ~3-5 ~3-5
Audible Noise Very Noisy Moderate Noise Silent Silent
Response Time ~50 ms ~30 ms 0.5 ms 0.5 ms
Energy Consumption High Low Lower Lower
High-Definition Haptics No No Yes Yes
Cost $ $$ $$ $$$