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Eccentric Rotating Mass Motor Control

Using GreenPAK™ with low dropout regulators (LDOs) provides a fully customizable, low-power solution to drive and control a wide variety of small ERM motors used in devices such as mobile phones, game controllers, etc. The programmable digital and analog resources in GreenPAK make it easy to implement custom features to differentiate your haptic experience as well as protection features to ensure smooth and safe operation, including:

  • Custom vibration strength
  • Custom vibration patterns and timing
  • Braking
  • Custom motor kick-start and
  • Over-current/short circuit protection
  • Over-temp protection

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GreenPAK Benefits for ERM Motor Control

GreenPAK Enhances Flexibility

  • VDD is 2.5 to 5.0 V
  • Integrated delays for programmable button de-bounce
  • Inter-Integrated Circuit (I2C) interface allows changes to vibration patterns and timing
  • General-purpose input/output (GPIO) routing is flexible ensuring the least complexity in PCB routing

GreenPAK Lowers Power Consumption

  • GreenPAK provides low-power consumption with the best performance

GreenPAK Ensures System Stability

  • Integrated LDO protection
  • Zero Code as implementing features in hardware ensures stability
  • Integration of many components ensuring fewer points of failure
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Vibration Patterning and Strength

Using GreenPAK’s programmable digital and timing blocks it is possible to make a number of different vibration patterns. With the LDOs integrated into the GreenPAK, which can switch between two voltage outputs using digital logic and up to 32 different levels via I2C, it is also possible to create vibrations of different strengths.

Kickstart

  • To quickly start an ERM motor, it is useful to drive it at a higher voltage for a short duration. This overcomes the momentum of the still mass and allows for cleaner vibration patterns.

Braking

  • Some ERM motors include a special pin for braking. Using digital logic and GreenPAK’s configurable GPIO, driving the braking pin anytime the motor should stop is easy.

Pattern and Kickstart Circuit in GreenPAK

Functional Waveforms

Protection

The LDOs in GreenPAK contain over-current and short circuit detection which will cause the LDO to shut down in the event of a failure. Additionally, using the integrated temperature sensor and programmable analog comparator (ACMP), it is easy to implement over-temperature shutdown as well.

Overcurrent & Short Protection LDO Settings 

Over-temperature Protection Circuit in GreenPAK

View the full list of the GreenPAK videos in our Training Video Library.